2007 NIST CENTER FOR

NEUTRON RESEARCH

	 	 	 	 	 	 	 	

ACCOMPLISHMENTS

AND OPPORTUNITIES

	 	 	 	 	 	 NIST Special Publication 1075 	 	

	 	 	 	 	 	 	

Patrick D. Gallagher, Director

	 	 	 	 	 	 	   Ronald L. Cappellet

	 	 	 	 	 	 	 	 

	 	 	 	

	 	 	 	 	 National Institute of Standards and Technol

	 	 	 	 	 	   James Tu

	 	 	 	 	 	

	 	 	 	 	 	 	 U.S. Department o

	 	 	 	 	 	 	 Carlos M. Gutierrez, Secretary
DISCLAIMER

Certain commercial entities, equipment, or materials may be identified

in this document in order to describe an experimental procedure or

concept adequately. Such identification is not intended to imply

recommendation or endorsement by the National Institute of Standards

and Technology, nor is it intended to imply that the entities, materials,

or equipment are necessarily the best available for the purpose.

National Institute of Standards and Technology

Special Publication 1075

Natl. Inst. Stand. Technol. Spec. Publ. 1075, 88 pages

(December 2007)

CODEN: NSPUE2

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Table of Contents

iv FOREWORD

1 THE NIST CENTER FOR NEUTRON RESEARCH

2 NIST CENTER FOR NEUTRON RESEARCH INSTRUMENTS

4 NCNR EXPANSION 2007 ACTIVITIES

HIGHLIGHTS

INSTRUMENTATION

6	 The New BT-7 Thermal Triple Axis Spectrometer

CHEMICAL PHYSICS

8	 The Density Minimum in Deeply Supercooled

Confined Water

10	 Hydrogen Absorption Properties of Metal-Ethylene

Complexes

12	 Exceptionally Stable Organic Glasses

14	 Hydrogen Storage in a Prototypical Zeolitic Imidazolate

Framework-8

CONDENSED MATTER

16	 Bose-Einstein Condensate of Magnons in Coupled

Spin Ladders

18	 Magnetic Resonance Mode and the Superconducting

Condensate in a High-Tc Cuprate

20	 Interfacial Domain Walls in Perpendicular MagneticMedia Prototypes

22	 Discovery of Zone Boundary Soft Modes in the Relaxor

Ferroelectric PMN

24	 Hidden Order in URu Hidden Order in URu2Si2

26	 Quantum Coherence in a Spin Chain

ENGINEERING PHYSICS

28 	 The Nanoscale Building Blocks of Concrete

30	 Biaxial Fatigue Failure in Gas Pipelines

SOFT MATTER/POLYMERS

32	 Lateral Roughness of Buried Interfaces in Extreme UV

Lithography Photoresists

34	 Nanostructured Liquids from Disordered

Surfactant melts Blended with Functional

Homopolymers

36	 A Class of Micellar Solutions with Viscosity

Tunable by Light

38	 Glass Transition Behavior of Thin Film Miscible

Binary Polymer-Polymer Blends

BIOLOGY

40	 Alzheimer’s Disease: Effects of β-Amyloid

Oligomers on Cell Membranes

42	 Protein Structure and Hydration Probed

by SANS

44	 Melting in Dehydrated Lipid Bilayers

46	 Revealing Light-Enhanced Protein Activity

with Neutrons

48 NCNR IMAGES 2007

ADVANCES IN MEASUREMENT

50	 Extending Neutron Activation

Analysis Capabilities

51	 Reciprocal Space Neutron Imaging

52	 3He Spin Filters for Polarized Neutron

Scattering Experiments

53	 Trace Fissionable Material Analysis: New

Metrology Facility

54	 Direct Measurement of the Vertical

Coherence Length of Neutron Waves

55	 NEUTRON SOURCE OPERATIONS

56 FACILITY DEVELOPMENTS

58 SERVING THE SCIENCE AND TECHNOLOGY 

COMMUNITY

60 THE CENTER FOR HIGH RESOLUTION NEUTRON 

SCATTERING (CHRNS)

62 AWARDS 2007

64 PUBLICATIONS

79 INSTRUMENTS AND CONTACTS

CONTACTS (inside back cover)

NCNR 2007 ACCOMPLISHMENTS AND OPPORTUNITIES

iii
I am delighted to present you with yet another summary of the strong research accomplishments

and productivity that have taken place at the NIST Center for Neutron Research during the

past year. Our 2007 annual report focuses on research highlights that have been selected f

many different areas to illustrate the large body of exciting science being conducted at the

NCNR. While these highlights serve to demonstrate the substantial breadth and quality of t

research done this past year, I feel they also reflect the enjoyment and dedication of researchers

themselves. To learn more about the numerous NCNR activities I encourage you to visit 

website at www.ncnr.nist.gov, where you can get additional information on the many other

projects that the limited space here does not allow us to include.

The past year has been an especially exciting one for the facility. The fiscal year 2007 budget included the full fundi

requested to begin the planned expansion of the NCNR. The first year of this five year effort includes activities 

instrumentation design, cold source development, guide system design, civil construction, and a project to modernize

the reactor control room. While this is a huge challenge, by all reports the effort is off to a great start. Further det

are included in this report, and updates will be made available on the NCNR web site.

In what has now become routine performance by our hardworking and talented staff, the past 12 months have seen

256 beam days of highly reliable operations of the reactor, cold source, and instruments; the importance of this record

cannot be overstated because it enables the enormous amount of research performed at the NCNR year in and year

out. Our Reactor Operations and Engineering staff has also made great progress on a number of long-standi

upgrade projects and has continued its work in support of our application for a renewal of the operating license.

Both efforts are critical to our continued success and several pertinent highlights are included in this report. T

development of new instruments and new sample environment capabilities remains a high priority in spite of the

increased demands associated with the NCNR expansion. This year the new thermal, triple-axis spectrometer locat

at BT-7 was commissioned and began to accept beam time requests and proposals through our user program. To da

our most advanced and versatile triple-axis instrument, the major gains in performance on BT-7 have already generated

considerable enthusiasm by its users.

This year also saw important changes in the leadership of the NCNR. Charlie Glinka retired as leader of the Resear

Facility Operations (RFO) Group in January after 32 years at NIST. Charlie will always be synonymous with small ang

neutron scattering at NIST, but his talent, energy, and enthusiasm contributed to the success of the NCNR in many ways.

Rob Dimeo returned from a detail at the White House Office of Science and Technology Policy to assume responsibility

for the RFO group, and to take the new position of Deputy Director of the NCNR.

One particularly enjoyable part of my job as Director is to see the hard work and dedication of the NCNR staff and

users acknowledged through awards and other forms of external recognition. The past year has provided us wit

remarkable list of impressive achievements, and a summary of awards is included in this report. I wish to include 

sincere congratulations to the awardees! This report too is a celebration of the work and dedication of all those t

work and use the NCNR - so let me take this opportunity to express my warm thanks to everyone for another great year.

Foreword

iv
The NIST Center for Neutron Research

Neutrons are superb probes of the structure and dynamics

of materials ranging from water penetrating the crevices of

proteins to atomic magnets ordering in computer hard-drive

materials. The properties of neutrons (outlined below) can

be exploited using a variety of measurement techniques to

provide information not otherwise available. Atomic motion

can be directly measured and monitored. Neutrons are

especially sensitive to hydrogen, so that its motion can be

followed in prototype storage materials, in unfolding proteins,

or in the incorporation of water during the setting of cement.

Residual stresses such as those deep within natural gas pipeline

welds or in highway trusses can be mapped. Neutron-based

measurements contribute to a broad spectrum of activities

including in engineering, materials development, polymer

dynamics, chemical technology, biological studies, and physics.

The NCNR’s neutron source provides the intense, conditioned

beams of neutrons required for these types of measurements.

In addition to the thermal neutron beams from the heavy

water or graphite moderators, the NCNR has a large area

liquid hydrogen moderator, or cold source, that provides long

wavelength guided neutron beams for the major cold neutron

facility in the U.S.

There are currently 29 experiment stations: four provide high

neutron flux positions for irradiation, and 25 are beam facilities

most of which are used for neutron scattering research. The

subsequent pages provide a schematic description of our

instruments. More complete descriptions can be found at www.

ncnr.nist.gov/instruments/. The NCNR is currently adding

a second guide hall with five new instruments in a major

expansion (see pp. 4–5).

The Center supports important NIST measurement

needs, but is also operated as a major national user

facility with merit-based access made available to the

entire U.S. technological community. Each year, mo

than 2000 research participants from government,

industry, and academia from all areas of the country use

the facility. Beam time for research to be published in

the open literature is without cost to the user, but full

operating costs are recovered for proprietary research.

Access is gained mainly through a web-based, peerreviewed proposal system with user time allotted by a

beamtime allocation committee twice a year. For detai

see www.ncnr.nist.gov/beamtime.html. The National

Science Foundation and NIST co-fund the Center for

High Resolution Neutron Scattering (CHRNS) that

operates six of the world’s most advanced instruments.

Time on CHRNS instruments is made available through

the proposal system. Some access to beam time f

collaborative measurements with the NIST science staff

can also be arranged on other instruments.

NCNR 2007 ACCOMPLISHMENTS AND OPPORTUNITIES

1

Cold neutron Guide Hall and instruments. A second Guide 

Hall is under construction.

Why Neutrons?

Since neutrons are charge-neutral and easily penetrate matter,

they can reveal properties that electrons and photons cannot.

They can behave like microscopic magnets, they can propagate

like waves, they can set particles into motion losing or gaining

energy and momentum in the process, and they can be absorbed

with subsequent emission of characteristic radiation.

WAVELENGTHS–in practice range from ≈ 0.01 nm (thermal) to

≈ 1.5 nm (cold) (1 nm = 10 Å), allowing neutron waves to form

observable ripple patterns from structures as small as atoms to

as large as cells.

ENERGIES–of meV, the same order as those of motions of

atoms in solids or liquids, waves in magnetic materials, and

vibrations in molecules. Exchanges of energy between neutrons

and matter as small as neV and as large as tenths of eV can be

detected.

SELECTIVITY–in scattering power varies from nucleus to nucleus

somewhat randomly. Specific isotopes can stand out fr

other isotopes of the same kind of atom. Specific light atoms,

difficult to observe with x-rays, are revealed by neutrons.

Hydrogen, especially, can be distinguished from

chemically equivalent deuterium, allowing a variety of

powerful contrast techniques.

MAGNETISM–makes the neutron sensitive to the

magnetic spins of both nuclei and electrons, allowing

the behavior of ordinary and exotic magnets to be

detailed precisely.

NEUTRALITY–of the uncharged neutrons allows them to

penetrate deeply without destroying samples, and pass

through walls conditioning a sample’s environment,

allowing measurements under extreme conditions of

temperature and pressure.

CAPTURE–characteristic radiation emanating from

specific nuclei capturing incident neutrons can be used

to identify and quantify minute amounts of materials in

ancient pottery shards or lake water pollutants.
2

NIST Center for Neutron Research Instruments

[1]	 BT-5 Perfect Crystal Ultra-Small Angle Neutron

Scattering (USANS) Diffractometer for microstructure

up to 104 nm, part of CHRNS.

[2]	 BT-4 Filter Analyzer Neutron Spectrometer with cooled

Be/Graphite filter analyzer for chemical spectroscopy.

[3]	 BT-2 Neutron Imaging Facility for imaging hydrogenous

matter in large components such as water in fuel cells

and lubricants in engines, in partnership with General

Motors.

[4] 	BT-1 Powder Diffractometer with 32 detectors; incident

wavelengths of 0.208 nm, 0.154 nm, and 0.159 nm, with

highest resolution of δd/d = 8 x 10-4.

[5] 	BT-9 Thermal Triple Axis Spectrometer for measurements

of excitations and structure in condensed matter.

[6] 	BT-8 Residual Stress Diffractometer optimized for dep

profiling of residual stresses in large components.

[4]

[3]

[24]

[25]

[2]

[1]

[6]

[7]

[8]

[9]

[22]

[23]

[21]

[11]

[12]

[10] [5]

The Center for High Resolution Neutron Scattering (CHRNS) is a

partnership between NIST and the National Science Foundation that

develops and operates neutron scattering instrumentation for use by

the scientific community. The following instruments are part of the

Center: 1 (USANS), 13 (HFBS), 14 (NG-3 SANS), 15 (DCS), 22 (NSE),

and 23 (SPINS).
NCNR 2007 ACCOMPLISHMENTS AND OPPORTUNITIES

3

[7] VT-5 Thermal Neutron Capture Prompt Gamma-ray 

Activation Analysis Instrument with a neutron fluence 

rate of 3 x 108/cm2/s used for quantitative elemental 

analysis of bulk materials. Generally used for the analysis of highly hydrogenous materials (≈ 1 % H) such as 

foods, oils, and biological materials.

[8] BT-7 Thermal Triple Axis Spectrometer with large 

double focusing monochromator, and interchangeable 

analyzer/detectors systems.

[9] NG-0 MACS a cold neutron triple axis crystal 

spectrometer (under construction) with double 

focusing monochromator and multiple crystal 

analyzer/detectors that can be flexibly configured 

for several energies simultaneously or for high 

throughput at one energy. 

[10]NG-1 Advanced Neutron Diffractometer/Reflectometer 

(AND/R) a vertical sample reflectometer with polarization analysis and off-specular reflection capabilities for 

measuring reflectivities down to 10-8.

[11]NG-1 Vertical Sample Reflectometer instrument

with polarization analysis capability for measuring 

reflectivities down to 10-8 to determine subsurface 

structure.

[12]NG-1 Cold Neutron Depth Profiling 

instrument for quantitative profiling of subsurface 

impurities.

[13]NG-2 Backscattering Spectrometer (HFBS)

high intensity inelastic scattering instrument with 

energy resolution < 1 μeV, for studies of motion in 

molecular and biological systems, part of CHRNS.

[14]NG-3 30 m SANS for microstructure measurements, 

part of CHRNS.

[15]NG-4 Disk Chopper TOF Spectrometer for studies 

of diffusive motions and low energy dynamics of 

materials. Wavelengths from ≈ 0.18 nm to 2.0 nm 

give corresponding energy resolutions from 

≈ 2 meV to < 10 μeV, part of CHRNS.

[16-18] NG-6 Neutron Physics Station offering three 

cold neutron beams having wavelengths of 

0.5 nm, 0.9 nm, and “white” that are available for 

fundamental neutron physics experiments.

[19]NG-7 30 m SANS for microstructure measurements, 

in partnership with NIST and ExxonMobil.

[20]NG-6 Neutron Physics Test Bed for developing 

measurement techniques of the neutron 

magnetic dipole and electric dipole moments.

[21]NG-7 Prompt Gamma Activation Analysis with 

sufficient cold neutron flu to allow detection of 

H of 1 μg to 10 μg, depending on the matrix. 

Focused beams are available for profiling.

[22]NG-5 Spin-Echo Spectrometer (NSE) for measuring 

dynamics from 100 ns to 10 ps, in partnership with 

ExxonMobil, part of CHRNS.

[23]NG-5 Spin-Polarized Triple Axis Spectrometer 

(SPINS) using cold neutrons with position 

sensitive detector capability for high-resolution 

studies, part of CHRNS.

[24]NG-7 Neutron Interferometry and Optics Station

with perfect crystal silicon interferometer. A 

vibration isolation system provides exceptional 

phase stability and fringe visibility.

[25]NG-7 Horizontal Sample Reflectometer

allows reflectivity measurements of free surfaces, 

liquid/vapor interfaces, as well as polymer coatings.

[16-18]

[20]

[19]

[15]

[14]

[13]
4

NCNR Expansion 2007 Activities
NCNR 2007 ACCOMPLISHMENTS AND OPPORTUNITIES

5

See www.ncnr.nist.gov/expansion/for details
Amajor milestone was achieved in the modernization

of the NCNR’s thermal neutron instruments with the

installation and commissioning of the new multi-mode

analyzer system on the thermal triple-axis spectrometer

(TAS) at the BT-7 beam port. The installation of the new

analyzer system completes the basic construction of the new

instrument, which is shown in operation in Fig. 1.

The New BT-7 Thermal Triple Axis Spectrometer

J. W. Lynn, Y. Chen, M. Murbach, C. Wrenn, C. Brocker, N. Maliszewskyj, J. Ziegler1

1NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899

Instrumentation

The white drum is the new analyzer, which is shown

schematically in Fig. 2. The pyrolitic graphite (PG) cryst

(002) analyzer array consists of 13 individual blades that

can be used in flat or horizontally focusing configurations

in combination with a linear position sensitive detector or

conventional Söller collimators. An array of 11 detectors

embedded in the door behind the analyzer continuously

monitors the neutron flux entering the

analyzer to check for intense scattering from

the sample that might give rise to a spurious

count rate in the detector.

The analyzer system has five basic modes

of operation that are computer-controlled

and can be selected and interchanged by

the experimenter without requiring any

mechanical reconfiguration or hands-on user

intervention inside the analyzer housing.

The simplest mode places a separate

diffraction detector in front of the crystal

analyzer, to align the scattering angle or to

make conventional Bragg peak

intensity measurements.

A second mode is the “standard” triple-axis

configuration in which the analyzer is used in

the flat configuration with Söller collimators

before and after the analyzer. One additional

feature is that the door detectors can then

FIGURE 2: Schematic diagram of the new analyzer system for the 

BT-7 thermal triple axis spectrometer. 

The green drum houses the double focusing monochromator

system, with a choice of PG(002) or Cu(220) crystals

that provide a continuous incident energy range from

5 meV to 500 meV. The 400 cm2 reflecting area of each

monochromator yields as much as an order-of-magnitude

gain of neutrons onto the sample compared with other

thermal triple-axis spectrometers at the NCNR. The reactor

beam and post monochromatic beam elements (collimators,

slits, and filters) offer a wide range of choices to optimize

the resolution and intensity of the instrument, with flux

onto the sample as high as 2⋅108 n/cm2/s. The sample

stage allows a wide variety of sample environments to be

used—refrigerators, cryostats, furnaces, and magnets. The

instrument includes two coaxial rotary tables, one for sample

rotation and one for the independent rotation of magnetic

field coils, and a computer-controlled sample goniometer

and elevator.

6

FIGURE 1: Picture of the BT-7 thermal triple axis instrument in operation.
NCNR 2007 ACCOMPLISHMENTS AND OPPORTUNITIES

be used to simultaneously determine the instantaneous

correlation function. A third mode (manually) places a

radial collimator in the sample-to-analyzer (S-A) position

and the position-sensitive detector (PSD) in the straightthrough position to provide a simultaneous measurement

of the scattering along an arc in reciprocal space for single

crystal specimens, which will greatly accelerate making maps

of diffuse scattering, for example, or may be used to monitor

the intensity and position of a Bragg peak associated with a

magnetic or structural phase transition.

Alternatively, for a powder specimen a measurement of the

diffraction pattern over a range of angles can be obtained

simultaneously. This will greatly reduce the time to obtain

a (coarse resolution) diffraction pattern, or can be used to

quickly measure the integrated intensity of a Bragg peak

associated with a magnetic or structural phase transition.

A fourth option is to use a radial S-A collimator and the

PG array in horizontal energy focusing mode with either

the single detector or PSD depending of the measurement

needs. For problems where the analyzer resolution can

be relaxed this can more than triple the signal. Analyzer

configurations other then energy focusing are also possible.

The fifth mode is to use open S-A collimation, a flat PG

array, radial collimator after the crystal analyzer and the

PSD to measure a range of (Q, E) simultaneously. These

five measurement capabilities provided by the new analyzer

system greatly increase flexibility for the experimenter.

Finally, we note that all these configurations can be utilized

with 3He polarizers before and after the sample, along with

computer controlled polarization direction at the sample,

to enable measurements of all eight of the conventional

polarized neutron cross sections.

The electronic systems for the new instrument are

distributed among its components. Controls for the

primary spectrometer (beam conditioning, sample table,

monochromator drum, double focusing monochromator,

scattering angle) reside atop the monochromator drum.

All controls for the secondary spectrometer (analyzer

motors, detector electronics, airpad controls), on the other

hand, are housed in an enclosure on the analyzer itself.

The only physical connections of the analyzer system to

the rest of the instrument are a mechanical coupling,

compressed air (for the air-pad system), electrical power,

and ethernet communications. The distributed nature of

the electronics and the simple linkage of the analyzer to

the primary spectrometer are designed to both alleviate

heavy cabling burdens and to facilitate interchangeability

of the analyzer. In particular, if a different type of analyzer

capability is required, such as a double focusing array with

a detector buried in shielding, an analyzer with a different

crystal choice, or a multi-crystal/multi-detector array, then

the separate analyzer can be installed by floating it in

on air pads, attaching it to the scattering angle arm, and

simply connecting power, air, and communications. The

future development of additional types of analyzers will add

important measurement capabilities both for the thermal

as well as for the cold triple axis instruments.

Because of the high demand for thermal TAS measurement

capability in the U. S. combined with the dearth of available

instruments both in the U.S. as well as Europe during the

last few years, the new instrument was pushed into service

early by installing a conventional analyzer system to make

the instrument operational as a triple-axis spectrometer in

the interim. This affords a ready comparison to the dramatic

improvement in performance with the new analyzer, as

shown in Fig. 3.

With conventional Söller collimators before and after the

analyzer, the improvement in performance is ≈ 2.4, which

comes primarily from the increased analyzer/detector

height. Relaxing the angular divergence by employing

horizontal focusing mode provides a factor of 6.2 gain in

signal. Overall improvement in performance of the entire

instrument is one to two orders-of-magnitude in signal

compared with traditional thermal triple axis spectrometers,

depending on the type of measurement being performed.

In addition, the fast-neutron background for the new

instrument has been substantially improved compared to

traditional TAS instruments. The new instrument provides a

signal that is comparable to the best TAS instruments in the

world, and a measurement flexibility that is unparalleled.

FIGURE 3: Energy scan through the incoherent scattering of a 

vanadium calibration sample, comparing the conventional analyzer 

with the new analyzer in flat mode, and with horizontal focusing.

7
The Density Minimum in Deeply

Supercooled Confined Water

D. Liu, Y. Zhang, S.-H. Chen1; C.-C. Chen, C.-Y. Mou2; P. H. Poole3

Chemical Physics

I

n this article we highlight a report of the first experimental

evidence of the existence of the density minimum in

supercooled water [1]. Using the NG-7 small angle neutron

scattering (SANS) instrument at the NCNR, we measured

the density of heavy water contained in 1-D cylindrical pores

of mesoporous silica material MCM-41-S-15 having pores

of diameter of (15 �� 1) Å. In these pores the homogenous

nucleation process of bulk water at 235 K does not occur and

the liquid can be supercooled down to at least 160 K. The

analysis of SANS data allows us to determine the absolute

value of the density of D2O as a function of temperature.

We observe a density minimum at (210 �� 5) K with a value

of (1.041 �� 0.003) g/cm3. We	show that the results are

consistent with the predictions of molecular dynamics

simulations of supercooled bulk water.

The 17th century discovery of the density maximum in

water at 4 °C demonstrates the long history of water

science [2]. Incredibly, it took another 320 years to

observe that water has a density minimum at an even

lower temperature [1]. The reason may be that bulk

FIGURE 1: SANS intensity distribution as a function of Q and T. The peak 

in I-Q plane is due to Bragg diffraction of the 2-D hexagonal lattice 

in grains of the silica crystallites (right inset). The height of the diffraction 

peak is a quadratic function of the density of D2O inside the cylindrical 

pore. The saddle point indicates the density minimum point of supercooled confined heavy water. The left inset shows a contour of 

the intensity surface.

FIGURE 2: Model analysis of SANS intensity distribution. (A) The blue 

circles show the SANS data (at 250 K) with the contribution of the 

interfacial (surfaces of the grains) scattering subtracted. The red solid 

line represents the fitted curve using the model given in Ref. 1. The 

black line represents the structure factor S(Q) of the 2-D hexagonal 

lattice. The green line represents the form factor P(Q) of the cylindrical 

column tube of D2O. (To make the figure clearer, the magnitude of S(Q) 

is multiplied by a factor 3x10-4) . (B) SANS data and their fitted curves 

(solid lines) for different temperatures. Four curves are selected to 

show the good agreement between the model analyses and the 

experimental data.

1Massachusetts Institute of Technology, Cambridge, MA, 02139

2National Taiwan University, Taipei, Taiwan 106

3St. Francis Xavier University, Antigonish, Nova Scotia, B2G 2W5, Canada

8
NCNR 2007 ACCOMPLISHMENTS AND OPPORTUNITIES

FIGURE 3: Comparison of density versus temperature curves at ambient 

pressure for bulk liquid D2O (triangles) [CRC handbook], confined liquid 

D2O (solid circles) from this work, D2O ice Ih (solid squares), and MD simulations of liquid TIP5P-E water (open diamonds). The density values for 

the TIP5P-E model (which is parametrized as model of H2O) have been 

multiplied by 1.1 to facilitate comparison with the behavior of D2O.

The finding of a density minimum also has significant

implications for the proposal that a liquid-liquid phase

transition occurs in supercooled water [6]. These

implications arise because a formal relationship exists

between density anomalies and response functions, such as

the isothermal compressibility KT and the isobaric specific

heat CP. Our finding reinforces the plausibility that there is

a Widom line emanating from the liquid-liquid critical point

in supercooled water passing between Tmin and Tmax, as was

indicated in our previous experiment [3] which detected the

dynamic crossover phenomenon at 225 K at ambient pressure.

References

[1] D. Liu, Y. Zhang, C.-C. Chen, C.-Y. Mou, P. H. Poole, and

S.-H. Chen, Proc. Natl. Acad. Sci., 104, 9570 (2007).

[2] R. Waller, Essays of Natural Experiments (1684),

(Johnson Reprint Corporation, New York, 1964)

[3] L. Liu, S.-H. Chen, A. Faraone et al., Phys. Rev. Lett. 95,

117802 (2005).

[4] D. Paschek, Phys. Rev. Lett. 94, 217802 (2005).

[5] P. H. Poole, I. Saika-Voivoid and F. Sciortino, J. Phys: Condens.

Matter 17, L431 (2005).

[6] P. G. Debenedetti and H. E. Stanley, Physics Today 56, No. 6,

40 (2003).

water inevitably crystallizes into hexagonal ice below its

melting point (at 0 °C) and so far it has not been possible

to measure the density of bulk liquid water at the low

temperature where the density minimum occurs. We have

been able to bypass this difficulty by confining water and

have demonstrated that if it is kept from freezing at this

temperature there is a well-defined density minimum at

210 K in D2O.

Our sample was a MCM-41-S-15 powder which is made of

a micellar templated mesoporous silica matrix and has

1-D cylindrical pores arranged in a 2-D hexagonal lattice

[3]. The sample was fully hydrated with D2O for the

measurement. In this experiment, we chose the material

with a pore diameter of (15 �� 1) Å because differential	

scanning calorimetry data showed no freezing peak down

to 160 K for the fully hydrated sample. Based on a detailed

analysis of the SANS data, we find that the height of

the Bragg peak of the hexagonal lattice is related to the

scattering length density (SLD) of D2O inside the silica

pores. The SLD of D2O is proportional to its mass density

rD2O. Hence, we are able to determine the density of water

(D2O) by measuring the temperature-dependent neutron

scattering intensity I(Q) (see Fig. 1). Detailed analysis is

illustrated in Fig. 2.

Consistent with these experimental results, a number of

recent molecular dynamics (MD) computer simulation

studies predict that a density minimum occurs in water

(H2O) (see Fig. 3) [4,5]. Compared to experiments on

bulk water, these computer simulation studies achieve deep

supercooling without crystal nucleation due to the small

system size and short observation time explored.

m

9
W. Zhou1, 2; T. Yildirim1, 2; E. Durgun3, S. Ciraci3

Chemical Physics

The success of future hydrogen and fuel-cell technologiesis critically dependent upon the discovery of new

materials that can store a large amount of hydrogen at

ambient conditions. The current obstacles in hydrogen

storage are slow kinetics, poor reversibility and high

dehydrogenation temperatures for the chemical hydrides,

and very low desorption temperatures or energies for the

physisorption materials. Recently, we have suggested a novel

concept to overcome these obstacles [1-2]. We predicted

that a single Ti atom affixed to carbon nanostructures

(Fig. 1), such as C60 or nanotubes, strongly adsorbs up to

four hydrogen molecules with a binding energy of 0.4 eV

compatible with room temperature desorption/absorption.

Unfortunately, synthesizing the predicted structures of Ti

decorated nanotubes/C60 was proven to be very difficult.

In searching for a more efficient and feasible high capacity

hydrogen-storage medium, we found that the C=C double

bond of an ethylene molecule C2H4, mimics double bonds

of C60 that strongly binds the transition metal (TM) atom

(see Fig. 1) and therefore it is expected to support TM

atoms strongly to provide a basis for high-capacity hydrogen

storage via the Dewar-Kubas mechanism. In this article, we

highlight our exploration of this idea [3, 4].

Our results are obtained from first-principles plane

wave calculations within density functional theory using

Vanderbilt-type ultrasoft pseudopotentials with PerdewBurke-Ernzerhof exchange correlation. Single molecules

have been treated in a supercell of (20 × 20 × 20) Å3 with

Γ k-point and a cutoff energy of 408 eV.

We first studied the bonding of a single Ti-atom to an ethylene

molecule to form C2H4Ti. We found no energy barrier for

this reaction. The Ti atom forms a symmetric bridge bond

with the C=C bond of ethylene with EB = 1.45 eV. Interestingly,

it is also possible to attach a second Ti atom to the C2H4Ti

to form C2H4Ti2 (Fig. 2) without any potential barrier and

about the same binding energy as the first Ti atom. Figure

2 shows that the bonding orbital for the Ti atoms and C2H4

results from the hybridization of the lowest-unoccupied

molecular orbital (LUMO) of the ethylene molecule and the

Ti-d orbitals, in accord with Dewar coordination.

We next studied the H2 storage capacity of the Ti ethylene

complex by calculating the interaction between C2H4Ti2

and a different number of H2 molecules and configurations.

The first H2 molecule is absorbed dissociatively to form

C2H4(TiH2)2 as shown in Fig. 3(a) with a binding energy

of 1.18 eV/H2. The additional hydrogen molecules do not

dissociate and molecularly absorbed around the Ti atom. Two

of these configurations are shown in Figs. 3(b) and 3(c). In

the C2H4(TiH2-2H2)2 configuration, two H2 are molecularly

bonded from the left and right side of the TiH2 group with

a binding energy of 0.38 eV/H2 and significantly elongated

H-H bond length of 0.81 Å. It is also energetically favorable

to add a third H2 molecule from the top of the TiH2 group,

with a binding energy of 0.4 eV and bond length of 0.82 Å.

The resulting structure, C2H4(TiH2-3H2)2, isshown in Fig. 3(c).

We note that these binding energies have the right order of

magnitude for room temperature storage. Since the hydrogens

FIGURE 1: (a) One of the most stable structures of the Ti-C60 complex, 

where the Ti atom (dark blue) is bonded to a C-C double bond with four 

hydrogen molecules attached (red). (b) The local structure of the Ti-C60

double bond. (c) Replacing the end carbon atoms shown in 

(b) by H results in an ethylene molecule. This suggests that we may 

simply use the ethylene molecule to hold Ti atoms, which then binds 

multiple hydrogen molecules.

FIGURE 2: Optimized structure of an ethylene-Ti complex, C2H4Ti2, 

showing that Ti-C2H4 bonding orbital results from the hybridization of the LUMO of the C2H4 and the Ti-d orbital, in accord with 

Dewar coordination.

1NIST Center for Neutron Research, National Institute of Standards and 

Technology, Gaithersburg, MD 20899

2University of Pennsylvania, Philadelphia, PA 19104

3Bilkent University, Ankara 06800, Turkey

10

Hydrogen Absorption Properties of

Metal-Ethylene Complexes
NCNR 2007 ACCOMPLISHMENTS AND OPPORTUNITIES

are absorbed molecularly, we also expect fast absorption or

desorption kinetics.

Finally, we also observed many other local stable

configurations where all of the hydrogen molecules are

bonded molecularly. One such configuration, denoted as

C2H4(Ti-5H2)2, is shown in Fig. 3(d). Here the H2 molecules

stay intact and benefit equally from bonding with the Ti

atom. The total of ten hydrogen molecules absorbed by a

single Ti-ethylene complex, C2H4(Ti-5H2)2, corresponds to

a mass fraction of ≈ 14 %.

The top hydrogen molecule in C2H4(Ti-5H2)2 has the

weakest bonding in the system with EB = 0.29 eV, whereas

the side H2 molecules have the strongest bonding with

EB = 0.49 eV/H2 and significantly elongated H-H bond

distance of 0.85 Å . This suggests the presence of two

different H2-C2H4Ti2 bonding orbitals as shown in Figs. 3(e)

and 3(f). The first one is a hybridization of the

top-H2 σ*-antibonding with the Ti-d orbital. The second

one is the simultaneous hybridization of the side H2

σ*-antibonding orbitals with the Ti-d orbital. Since the

bonding orbitals are mainly between metal d- and hydrogen

σ*-antibonding orbitals, the mechanism of this interesting

interaction can be explained by the Kubas interaction.

It is important to know if the above results for M = Ti hold

for other metals. We studied [4] a large number of them,

including the light metal Li. The results are summarized in

Table I. Scandium is the ideal case, but for practical reasons

Ti is the best choice. Cr binds very weakly while Zn does

not bind at all to the C2H4 molecule. Heavier metals such

as Pd and Pt can also form complexes with C2H4, but bind

fewer hydrogen molecules with significantly stronger binding

energy than Ti. For the alkali metal Li we also obtained

interesting results. The ethylene molecule is able to complex

with two Li atoms with a binding energy of 0.7 eV/Li. This

complex then binds up to two H2 molecules per Li with a

binding energy of 0.24 eV/H2 and an absorption capacity of

16 % mass fraction of hydrogen.

The stability of the proposed metal-ethylene complexes was

tested by extensive calculations such as normal-mode analysis, finite temperature first-principles molecular dynamics

simulations, and reaction path calculations [3, 4]. These calculations indicate that the proposed structures are stable up

to 500 K. Among many vibrational modes, we note that the

H2 stretching mode is around 330 meV to 420 meV for the

absorbed H2 molecules, significantly lower than ≈ 540 meV

for the free H2 molecule. Such a shift in the mode frequency

would be the key feature that can be probed by inelastic

neutron scattering measurement to confirm a successful

synthesis of the structures predicted here.

In conclusion, we showed that an individual ethylene

molecule functionalized by metal atoms can bind up to

several hydrogen molecules via the Dewar-Kubas interaction,

reaching a mass fraction gravimetric density as high as 16%.

These results suggest that co-deposition of transition/lithium

metals with small organic molecules into nanopores of lowdensity materials could be a very promising direction for

discovering new materials with better storage properties.

References

[1] T. Yildirim and S. Ciraci, Phys. Rev. Lett. 94, 175501 (2005).

[2] T. Yildirim, J. Iniguez, and S. Ciraci, Phys. Rev. B 72, 153403

(2005).

[3] E. Durgun, S. Ciraci, W. Zhou, and T. Yildirim, Phys. Rev. Lett.

97, 226102 (2006).

[4] W. Zhou, T. Yildirim, E. Durgun, and S. Ciraci, Phys. Rev. B,

in press (2007).

Li Sc Ti V Cr Mn Fe Co Ni Cu Zn Zr Pd Pt

EB(M) 0.70 1.39 1.45 0.94 0.18 0.51 0.92 1.39 0.91 0.80 – 1.91 1.95 2.52

EB (per H2) 0.28 0.28 0.46 0.53 0.21 0.18 0.34 0.28 0.42 0.33 – 0.54 0.27 0.25

max H2/M 2 5 5 5 5 5 5 3 2 2 – 5 2 2

TABLE 1: The metal-C2H4 binding energies (EB in eV/M atom) with respect to atomic energies of various metals, and the average H2 binding energies 

(in eV/H2) on C2H4M for maximum number of H2 molecules bonded to each metal.

11

FIGURE 3: Atomic configurations of an ethylene molecule functionalized by two Ti atoms, holding (a) two H2 molecules which are dissociated, (b) six H2 molecules, and (c) eight H2 molecules. Panel (d) shows 

a configuration where ten H2 are bonded all molecularly. The panel (e) 

and (f ) shows the bonding orbital for the top (e) and side hydrogen 

molecules, respectively. Note that the hydrogen σ*-antibonding orbitals 

are hybridized with Ti-d orbitals, suggesting Kubas interaction for the 

H2-Ti bonding.
Exceptionally Stable Organic Glasses

S. F. Swallen1; K. L. Kearns1; M. K. Mapes1; Y. S. Kim1; R. J. McMahon1; M. D. Ediger1; T. Wu, L. Yu1; S. K. Satija2

1University of Wisconsin, Madison, WI 53705

2NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899

Chemical Physics

FIGURE 1: Heat capacity, Cp, of TNB samples; blue: vapor-deposited 

directly into a DSC pan at 296 K at a rate of ≈ 5 nm/s ; black: ordinary 

glass produced by cooling the liquid at 40 K/min; ordinary glass 

annealed at 296 K for 174 days (violet), 328 K for 9 days (gold), and 328 K 

for 15 days (green). 

Glasses made from small organic molecules (organicglasses) have potential applications in many areas as

diverse as amorphous pharmaceuticals, optoelectronic,

photochromic and photovoltaic devices. In all of these

applications thermal and kinetic stability of the glass are

important criteria. Stability can be a problem for amorphous

pharmaceuticals in particular: if the internal structure

changes during storage, properties such as solubility also

will change, potentially undermining the effectiveness

of the drug. Conventional organic glasses produced by

cooling liquids at experimentally accessible rates often

show poor stability. Herein we show that vapor deposition 

of organic molecules can create high density glassy materials

with extraordinary thermodynamic and kinetic stability. We

attribute this substantial improvement in thermodynamic

and kinetic stability to enhanced molecular mobility within a

few nanometers of the glass surface during deposition.

Glassy materials combine the disordered structure of a liquid

with the mechanical properties of a solid. Glasses are usually

prepared by cooling a liquid, but accessing low energy states

by this route is impractically slow [1]. If a liquid avoids

crystallization as it is cooled, molecular motion eventually

becomes too slow to allow the molecules to find equilibrium

configurations. This transition to a nonequilibrium state

defines the glass transition temperature Tg. Glasses are

“stuck” in local minima on the potential energy landscape

[2,3]. Since glasses are thermodynamically unstable, lower

energies in the landscape are eventually achieved through

molecular rearrangements. However, this process is so slow

that it is generally impossible to reach states deep in the

landscape by this route.

We have discovered that vapor deposition can bypass

these kinetic restrictions and produce glassy materials

that have extraordinary energetic and kinetic stabilities, and

unusually high densities. We demonstrate this for two molecular

glass formers: 1,3-bis-(1-naphthyl)-5-(2-naphthyl)benzene

(TNB, Tg = 347 K) and indomethacin (IMC, Tg = 315 K).

For these systems, the most stable glasses are obtained when

vapor deposition occurs onto a substrate controlled near

Tg - 50 K, where Tg is the bulk value.

Differential scanning calorimetry (DSC) was used to

examine the kinetics and thermodynamics of vapordeposited samples created by heating crystalline TNB or

IMC in a vacuum. Figure 1 shows DSC data for TNB

vapor-deposited (blue) onto a substrate held at 296 K. This

scan was continued to above the melting point, after which

the sample was cooled into the glass and then scanned again

to yield the black curve. This latter curve represents the

behavior of an ordinary glass of TNB, with Tg = 347 K,

as defined by the onset temperature; it is consistent with

previously reported results for TNB [4]. Remarkably, the

vapor deposited sample has a significantly higher onset

temperature of 363 K. This indicates that the vapor-deposited

material is kinetically much more stable, since higher

temperatures are required to dislodge the molecules from

their glassy configurations. For comparison, we isothermally

annealed the ordinary glass for 6 months at 296 K and up to

15 days at 328 K (equilibrium was reached at 328 K). Vapordeposited samples created in only a few hours have much

greater kinetic stability than ordinary glasses aged for many

days or months below Tg.

We have used neutron reflectivity to characterize diffusion in

ordinary and stable glasses of TNB. As schematically shown in

the inset of Fig. 2, 300 nm films were prepared by alternately

vapor-depositing layers of protonated TNB (h-TNB) and

deuterated TNB (d-TNB). The specular reflectivity, R, was

measured as a function of beam angle relative to the sample

surface, and is plotted as a function of the wavevector q.

Reflectivity curves for TNB samples vapor-deposited at

different temperatures are presented in the main part of

Fig. 2. The peaks represent diffraction: only odd diffraction

12
NCNR 2007 ACCOMPLISHMENTS AND OPPORTUNITIES

References

[1] M. D. Ediger, C. A. Angell, S. R. Nagel, J. Phys. Chem. 100, 13200

(1996).

[2] P. G. Debenedetti, F. H. Stillinger, Nature 410, 259 (2001).

[3] F. H. Stillinger, Science 267, 1935 (1995).

[4] C. M. Whitaker, R. J. McMahon, J. Phys. Chem. 100, 1081 (1996).

[5] S. F. Swallen et al., Journal of Chemical Physics 124, 184501

(2006).

[6] S. F. Swallen et al., Science 315, 353 (2007).

FIGURE 2: Neutron reflectivity data for TNB glass multilayer films (inset) 

taken periodically while continuously annealing at 342 K. The substrate 

temperature during vapor deposition in (A) was 330 K; the decay of the 

harmonic peaks in occurs over 8 h and is due to bulk molecular diffusion 

[5]. In (B), remarkably, by simply changing the substrate temperature to 

296 K during deposition no detectible diffusion occurs over 

16 h.

orders are present, as expected for our symmetric multilayer samples. For samples deposited at low temperature,

diffraction can be observed up to 13th order, indicating very

sharp h-TNB/d-TNB interfaces.

Figure 2 shows a time series of neutron reflectivity

curves obtained for two vapor-deposited samples during

annealing at 342 K. The sample in panel A was deposited

at 330K. During 8 hours of annealing, all diffraction peaks

(except the first order peak) decay to zero, indicating that

substantial interfacial broadening has occurred due to

interdiffusion of h-TNB/d-TNB. The sample in panel B was

deposited at 296 K. During the 16 hours of annealing at

342 K, no detectable interdiffusion has occurred, even

on the single nanometer length scale. We emphasize

that the only difference between these two samples was

the temperature at which the substrate was held during

deposition. Figure 2A illustrates the behavior of an

ordinary glass annealed near Tg, as published earlier

[5]. Interdiffusion in this sample is characteristic of the

equilibrium liquid. In contrast, the sample deposited near

Tg - 50 K (Fig. 2B) is kinetically much more stable, in

qualitative agreement with the high onset temperature

shown for the vapor-deposited sample in Fig. 1. Consistent

with this result, we have observed in preliminary experiments

that crystal growth rates in stable TNB glasses are slower

than in ordinary glasses, although vapor-deposited samples

may contain crystal nuclei.

We attribute the enhanced stability and high density of

vapor deposited glasses to enhanced mobility within a few

nanometers of the surface of a TNB glass. Such mobility

would explain both the broad interfaces observed in the

as-deposited samples and the unusually stable glasses formed

by vapor-deposition. The surface-mobility mechanism for the

creation of unusually stable glasses is supported by an orderof-magnitude calculation. TNB samples vapor-deposited

at 296 K have interface widths of 2.5 nm, somewhat in

excess of the width associated with surface roughness. We

attribute 1 nm of interface width to surface mobility, and

given a deposition rate of 0.1 nm/sec, the molecules are

within the mobile surface layer for 10 s. Combining this

length and time yields an estimate for the surface diffusion

coefficient of 5 x 10-16 cm2/sec. For bulk TNB, this diffusion

coefficient is found near Tg, where the structural relaxation

time τα is a few seconds. Thus surface molecules plausibly

remain mobile for several structural relaxation times before

becoming buried, arguably long enough to find nearequilibrium configurations at 296 K. Recent experiments

also show that the optimum temperature for making

most stable glasses is near ≈ 0.85 Tg. Deposition below this

temperature does not produce stable glasses because at low

deposition temperatures the molecules do not have enough

time to relax into low energy configurations, i.e., there is a

deposition temperature window for achieving glass stability.

In summary we have shown that vapor deposited glasses of

TNB can be made unusually stable by depositing the glass

at lower temperatures of the order of 0.85 Tg. We speculate

that unusually stable glasses can be prepared for many

systems that can be vapor-deposited, if surface mobility is

enhanced and the substrate temperature is appropriately

controlled. Stable glasses could also impact technologies

such as amorphous pharmaceuticals, where stability against

crystallization is required in order to retain the enhanced

bioavailability of amorphous preparation. For more detailed

information on this system the reader is referred to our

recent article [6].

13
Hydrogen Storage in a Prototypical Zeolitic

Imidazolate Framework-8

H. Wu1, 2; W. Zhou1, 3; T. Yildirim1, 3

Chemical Physics

1NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899

2University of Maryland, College Park, MD 20742

3University of Pennsylvania, Philadelphia, PA 19104

FIGURE 1: (a) (001) view of refined crystal structure of ZIF8 host lattice 

from neutron powder diffraction along with the available free space 

(pore structure) for H2 occupation, based on van der Waals interactions. 

(b) A (111) view of the real-space Fourier-difference scattering-length 

density superimposed with 6-ring pore aperture of the ZIF8 structure, 

indicating the location of the first adsorption sites (red-yellow regions).

Crystalline porous compounds with well-defined nanoopenings have long been used as chemical filters

and gas-entrapment materials. Intense interest currently

surrounds their potential to store hydrogen for next

generation transportation applications. Zeolitic imidazolate

frameworks (ZIFs) are a new class of nanoporous

compounds which consist of tetrahedral clusters of MN4

(M = Co, Cu, Zn, etc.) linked by simple imidazolate ligands

[1,2]. As a subfamily of metal-organic frameworks (MOFs),

ZIFs exhibit the tunable pore size and chemical functionality

of classic MOFs. At the same time, they possess the

exceptional chemical stability and rich structural diversity

of zeolites [2]. Because of these combined features, ZIFs

show great promise for hydrogen storage applications.

However, in contrast to a large number of extensive studies

of other MOFs, no experimental work concerning the

nature of H2-ZIF interactions and the manner in which

hydrogen molecules are adsorbed has yet been reported.

Such fundamental studies hold the key to optimizing this

new class of ZIF materials for practical hydrogen storage

applications.

ZIF8 is a prototypical ZIF compound (Zn(MeIM)2,

MeIM = 2-methylimidazolate) with a sodalite (SOD) zeolitetype structure, exhibiting an interesting nanopore topology

formed by 4-ring and 6-ring ZnN4 clusters, as shown in Fig.

1. Since the nanopores are only accessible through narrow

6-ring funnel-like channels (Fig. 1a), one wonders how H2

molecules are adsorbed, where the major binding sites are

and what the binding energies are. This article highlights our

work using the Fourier difference analysis of neutron powder

diffraction data along with first-principles calculations to

provide answers to these questions for the first time [3].

ZIF8 was synthesized using a solvothermal method as

described in Ref. 2. Neutron powder diffraction data were

collected on the BT-1 diffractometer. Because of the large

incoherent cross section of H2, adsorption was studied as a

function of D2 concentration per ZIF8 molecular formula

(Zn6N24C48H60). Target amounts of D2, i.e., 3D2, 16D2, and

28D2 per 6Zn, were loaded into the ZIF8 sample at 70 K. One

H2/6Zn corresponds to ≈ 0.15 % mass fraction hydrogen

uptake. The sample was then cooled to 30 K at which point

the D2 was completely adsorbed. Once the system was

equilibrated at 30 K, the sample was further cooled to 3.5 K

before the diffraction measurement.

The top panel of Fig. 2 shows the neutron diffraction data

from the ZIF8 bare material measured at 3.5 K. The refined

lattice parameters and atomic positions of Zn, N and C

agree well with previously reported room temperature x-ray

diffraction result. The high resolution neutron diffraction

data also enabled us to unambiguously determine the

orientation (i.e., the hydrogen positions) of the methyl

group, which was not possible in the x-ray measurement.

FIGURE 2: Observed (dots), refined (line), and difference (noisy line) neutron powder diffraction profiles (λ = 2.079 Å, 3.5 K) for ZIF8 host lattice 

(space group I4 m) and ZIF8 with D2 loading of 28D2/6Zn. –

3

14
NCNR 2007 ACCOMPLISHMENTS AND OPPORTUNITIES

[1] X. C. Huang, Y. Y. Lin, J. -P. Zhang, X. M. Chen, Angew.

Chem. Int. Ed. 45, 1557 (2006).

[2] K. S. Park, Z. Ni, A. P. Cote, J. Y. Choi, R. D. Huang,

F.J. Uribe-Romo, H. K. Chae, M. O’Keeffe, O. M.Yaghi, Proc.

Natl Acad. Sci. USA 103, 10186 (2006).

[3] H. Wu, W. Zhou, T. Yildirim, J. Am. Chem. Soc. 129,

5314 (2007).

[4] T. Yildirim and M. R. Hartman, Phys. Rev. Lett. 94,

175501 (2005).

References

For comparison, the neutron diffraction patterns from ZIF8

with the following D2 concentrations: nD2 = 3, 16, 28 per 6Zn

are also shown in Fig. 2 (also see Ref. 3). Using the model

of the refined ZIF8 host structure, we performed Rietveld

structure refinements on the D2 adsorbed samples. The

Fourier difference method was used to find the scatteringlength density distribution for D atoms based on the

refinements ignoring the adsorbed D2 molecules. Fig. 1b is

an example of such a Fourier-difference plot, which clearly

shows that the initial adsorption site (i.e., D1) is on top of

the MeIM organic linker and close to the C=C bond, thus

termed the “IM site”.

Upon D2 loading, the order of site filling in ZIF8 was

determined to be sequential from D1 to D6, shown in Fig. 3.

The already mentioned D1 site and the second site (D2) are

both determined from the initial loading of 3D2/6Zn. The

latter site is located at the center of the channel of the 6-ring

opening (termed “channel site I”). For 16D2/6Zn loading,

the D1 and D2 sites are nearly fully occupied, and the third

adsorption site (D3) starts to populate. The third site is also

at the center of 6-ring opening but located on the other

side of the complex, so we termed it “D3: channel site II”.

This site is less favorable than the D2 channel site I due to

the presence of the methyl group, mainly a geometry effect.

Interestingly, the first three adsorption sites discussed above

form a pseudo-cubic “nanocage” with the edges slightly bent

toward the ZIF8 framework, as shown in Fig. 3c. We also

observed a small amount (≈ 5 %) of D2 adsorbed at a fourth

site (D4) located at the face center of the H2-nanocage.

With further D2 loading, the first three adsorption sites

were almost completely occupied. For the maximal loading

of 28D2/Zn, the fourth site discussed above as well as two

additional sites (D5 and D6) close to the center of the void

in ZIF8 (inside the nanocage formed by the first three

sites), are progressively occupied. The nearest neighbor

distances between these adsorption sites are about

3.04 Å, significantly shorter than 3.6 Å found in solid H2.

Self-assembled 3D interlinked hydrogen nanostructures with

short intermolecular distances were previously observed in

MOF5 [4] and seem to be a common novel feature of these

nanoporous metal-hybrid systems.

To understand the hydrogen host-lattice interactions

further, we also performed total-energy calculations from

density functional theory (DFT) using the plane-wave

implementation of the local-density approximation to DFT.

Consistent with experimental observation, our calculations

suggested that the IM and channel site I are the most

energetically stable adsorption centers. The calculated H2

binding energies for these two sites are 170 meV and

147 meV, respectively, in agreement with the larger

population of the IM site at low D2 loading.

In conclusion, we obtained detailed structural information

such as the orientation of the methyl groups, H2 adsorption

sites and binding energies in the ZIF8 structure for the first

time. The imidazolate organic linker is primarily responsible

for adsorption, in contrast to metal oxide-based MOFs.

This suggests that modification of the linkers rather than

metal types in ZIFs is more important to optimize these

materials for higher storage capacity. At high concentration

of hydrogen loading, ZIF8 is able to hold hydrogen

molecules up to a mass fraction of 4.2 % as self-assembled

nanostructures with relatively short intermolecular distances

compared to solid hydrogen. This suggests that ZIFs can

also be used as an ideal template host-material to generate

molecular nanostructures with interesting properties.

FIGURE 3: The hydrogen adsorption sites obtained from Fourier difference 

analysis. (a) Top and side views of first three adsorption sites near a Znhexagon opening. (b) Pseudo-cubic nanocage formed by D1, D2 and D3 

sites. (c) Tetrahedron-like nanocage formed by D5 and D6 sites. 

15
compared to the chain-axis magnon bandwidth, but is considerably larger than inter-chain interactions along the c and

b axes. The corresponding bandwidths are 0.4 meV and < 0.1

meV, respectively, and thus not potent enough to disrupt the

1D spin liquid.

Figure 3 shows INS spectra collected at the 1D AF zonecenter h = 0.5 in several fields using the SPINS 3-axis

spectrometer at the NCNR with 3.7 meV fixed incident

energy neutrons, horizontally focusing pyrolitic graphite

analyzer, and a BeO filter after the sample. As the field is

turned on, the single peak at μoH = 0 becomes divided in

three equidistant components. As the gap softens, commensurate long-range AF order sets in and gives rise to new magnetic Bragg reflections of type (h+1⁄2, k, l), h, k and l-integer.

The measured field dependence of the (0.5, -1, 0) peak is

consistent with a mean field critical exponent = 0.5

expected for a 3D BEC transition [3,4].

A key result of this work is a direct measurement of excitations of the magnetic Bose-Einstein condensate in IPA-CuCl3.

Data collected above the critical field are shown in Fig. 2b.

Three distinct excitation branches, two gapped and one gapless, are clearly visible, though the overall inelastic intensity is

reduced compared to lower fields. The gapless mode is fully

analogous to the phonon in a conventional BEC, being the

Goldstone mode associated with the spontaneous breaking

of O(2) symmetry. It is a collective excitation of the magnon

condensate and has a linear dispersion relation. At H > Hc

Bose-Einstein Condensate of Magnons in

Coupled Spin Ladders

V. O. Garlea, A. Zheludev1; T. Masuda2; H. Manaka3; L.-P. Regnault, E. Ressouche, B. Grenier4; 

J.-H. Chung, Y. Qiu5; K. Habicht, K. Kiefer6; M. Boehm7 

Field-induced transitions in quantum magnets can oftenbe interpreted in terms of Bose-Einstein condensation

(BEC) of magnons [1, 2]. Such transitions are fully equivalent to BEC of atoms in liquid 4He, laser-cooled gases in

magnetic traps. An interesting conundrum is presented by

BEC of magnons in weakly interacting gapped quantum

spin chains or ladders [2]. Here the disordered spin liquid

normal state is a unique property of 1-dimensional (1D)

topology. In contrast, the stability of the magnon condensate

at high fields is necessarily a 3D effect, and relies on residual

inter-chain interactions. The phenomenon is therefore one

of the more striking examples of dimensional crossover in

many-body quantum mechanics. Do the topology and onedimensionality of the normal state influence the properties

of the condensate? We addressed this question experimentally by a neutron scattering study of the field-induced BEC

in a prototypical spin ladder material, (CH3)2CHNH3CuCl3

(IPA-CuCl3) [3,4].

Both an isotropic spin Hamiltonian and some 3D

magnetic interactions are prerequisites of true BEC in

magnetic systems. At high fields the magnon condensate is

then a commensurate, gapless, 3D-ordered phase [2]. To

date, such transitions were detected experimentally in only

a handful of model compounds and, for mostly technical

reasons, the excitation spectrum at high fields could only be

studied in sufficient detail in the 3D system TlCuCl3 [5]. In

this material the disorder and spin gap in zero field are due

to local singlet ground states of structural spin dimers. Our

prototype compound IPA-CuCl3 is in fact a uniform S = 1⁄2

ladder system. It undergoes a magnetic BEC transition in

accessible fields and has energy scales ideally suited for

inelastic neutron scattering (INS) studies of the excitation

spectrum. The spin ladders in IPA-CuCl3 are built of

S = 1⁄2 Cu2+ ions and run parallel to the a axis of the triclinic

P1 crystal structure (Fig. 1).

Excitations from this quantum-disordered ground state are

revealed in INS experiments that directly probe the pair spin

correlation function S(q,ω). Fig. 2a shows a time-of-flight

(TOF) spectrum collected on an IPA-CuCl3 single crystal

sample at T = 100 mK in zero magnetic field using the Disk

Chopper Spectrometer (DCS) at the NCNR. The magnon,

with a steep parabolic dispersion along the a axis and a gap

at the 1D antiferromagnetic (AF) zone-center h = 0.5,

is clearly visible. The energy gap (Δ = 1.2 meV) is small

1Oak Ridge National Laboratory, Oak Ridge, TN 37831

2Yokohama City University, Yokohama City, Kanagawa, 236-0027, Japan

3Kagoshima University, Korimoto, Kagoshima 890-0065, Japan

4CEA-Grenoble, DRFMC-SPSMS-MDN, 38054 Grenoble Cedex 9, France

Condensed Matter

FIGURE 1: Layers of magnetic Cu2+ (red) and the bridging Cl- (green) ions 

in IPA-CuCl3, showing the spin ladders running along the a axis.

5NIST Center for Neutron Research, National Institute of Standards and 

Technology, Gaithersburg, MD 20899 and University of Maryland, 

College Park, MD, 20742

6BENSC, Hahn-Meitner Institut, D-14109 Berlin, Germany

7Institut Laue Langevin, 38042 Grenoble Cedex 9, France

a

c

16
it takes the place of the massive quadratically dispersive

single-magnon excitation seen below the critical field (Fig. 2a).

Similarly, the phonon in a conventional Bose gas is a linearly

dispersive collective mode that replaces quadratically dispersive individual particles in the normal state. The two massive

(gapped) excitations seen in Fig. 2b are descendants of the

Sz = 0 and Sz = 1 members of the Haldane triplet at H < Hc

and are thus specific to the magnetic case. Even though

above the critical field one finds 3D AF long range order,

the observed spectrum is distinct from that of spin waves in a

classical magnet. The latter are transverse-polarized precession waves in the long range order parameter field. For a

Heisenberg AF in an external magnetic field one expects

one gapless and one gapped spin wave, in contrast with two

gapped modes detected in IPA-CuCl3. The high field ordered

phase should therefore be described as a quantum spin solid,

in contrast to the classical spin solid in conventional magnets.

While the critical behavior and long-wavelength spectral

features in IPA-CuCl3 are very similar to those in spin-dimer

systems, the short-wavelength spin dynamics at the zone

boundary is strikingly different. We find that the two massive

excitations in IPA-CuCl3 undergo a qualitative change upon

the BEC transition. As seen in Fig. 2b, at μoH = 11.5 T, only 

% above Hc, their bandwidths are suppressed by over a factor

of two. At H > Hc the emergence of long-range AF order

breaks an additional discrete symmetry operation, namely

a translation by the structural period of the ladder. The

spontaneous doubling of the period implies that at

H > Hc the wave vectors h = 0, h = 0.5 and h = 1 become

equivalent magnetic zone centers. At the same time, h = 0.25

and h = 0.75 emerge as the new boundaries of the Brillouin

zone. The result is a formation of anticrossing gaps for

all magnons at these wave vectors, which translates into a

NCNR 2007 ACCOMPLISHMENTS AND OPPORTUNITIES

reduction of the zone-boundary energy of the two gapped

magnons in IPA-CuCl3.

Our experiments illustrate that any long-wavelength

characteristics of the field-induced magnetic BEC transition

and the magnon condensate, such as critical indexes,

emergence of the Goldstone mode and behavior of gap

energies, are universal. They are not affected by the 1D

topological nature of the normal state in spin chains and

ladders, and are very similar to those in local cluster spin

systems. In contrast, the short-wavelength properties can

be significantly different in these two classes of materials.

In coupled AF spin chains or ladders, unlike in many

couple dimer systems, and unlike in conventional BEC,

the transition breaks an additional discrete symmetry. The

result is a radical modification of the excitation spectrum.

References

[1] E. G. Batyev, L. S. Braginski, Sov. Phys. JETP 60, 781 (1984).

[2] T. Giamarchi, A. M. Tsvelik., Phys. Rev. B 59, 11398 (1999).

[3] V. O. Garlea, A. Zheludev, T. Masuda, H. Manaka,

L.-P. Regnault, E. Ressouche, B. Grenier, J.-H. Chung, Y. Qiu,

K. Habicht, K. Kiefer, and M. Boehm, Phys. Rev. Lett. 98,

167202 (2007).

[4] A. Zheludev, V. O. Garlea, T. Masuda, H. Manaka,

L.-P. Regnault, E. Ressouche, B. Grenier, J.-H. Chung, Y. Qiu,

K. Habicht, K. Kiefer, and M. Boehm, Phys. Rev. B., submitted;

arXiv:0705.1360 (2007).

[5] C. Ruegg, N. Cavadini, A. Furrer, H.-U. Gudel, K. Kramer,

H. Mutka, A. Wildes, K. Habicht, and P. Vorderwisch, Nature 423, 62

(2003).

FIGURE 2: TOF neutron spectra measured in IPA-CuCl3 in the 1D 

Haldane-gap spin liquid phase (a) and the 3D ordered BEC phase (b), 

at μoH = 0 and μoH = 11.5 T, respectively. Solid white arrows indicate 

the linearly dispersive gapless Goldstone mode. The abbreviation r.l.u. 

stands for reciprocal lattice units.

FIGURE 3: SPINS spectra and the measured gap energies at the 

1D AF zone center h = 0.5 as a function of applied magnetic field, 

at T = 100 mK. The magnetic field drives the energy of low-lying magnons to zero by virtue of the Zeeman effect, prompting them 

to condense at a critical field μoHc = 9.6 T

17
Magnetic Resonance Mode and the Superconducting

Condensate in a High-Tc Cuprate

S. D. Wilson, P. Dai, S. Li, J. Zhao1; J. W. Lynn2; G. Mu, H.-H. Wen3; P. G. Freeman, L.-P. Regnault4; K. Habicht5

Condensed Matter

Although the precise mechanism responsible for theformation of the superconducting condensate in

the high-transition-temperature (high-Tc) copper oxides

remains an area of ongoing research, vast experimental

efforts over the past two decades have shown conclusively

that magnetism plays an important role within the physics

of high-Tc superconductivity. One key challenge remaining

however is to experimentally identify the nature and

extent through which magnetism in these high-Tc cuprates

couples to the electronic charge carriers. Specifically,

the fundamental mode of coupling between magnetic

order (either static or fluctuating) and the quasiparticles

responsible for Cooper pair formation remains a pivotal

focus of research in the high-Tc community. In the work

highlighted here, we have performed studies on the BT-9

triple axis spectrometer at the NCNR using high magnetic

fields to explore the relationship between the well-studied

magnetic resonance mode in high-Tc cuprates and the

corresponding condensation energy of the superconducting

phase in an electron-doped cuprate, Pr.88LaCe.12CuO4-δ

(PLCCO, Tc = 24 K) [1]. Additionally, by capitalizing on

the relatively low field necessary to completely suppress

superconductivity in the n-type cuprates, we have measured

the detailed changes in the static and dynamic spin behavior

in a high-Tc cuprate as it is driven into its field-suppressed,

nonsuperconducting ground state.

In searching for magnetic properties that demonstrate a

clear coupling to the superconducting phase in the high-Tc

cuprates, one particular feature—the magnetic resonance

mode—has been promising. The resonance mode itself

is a collective spin excitation within the CuO2 planes of

the cuprates and is observed along the commensurate

antiferromagnetic (AF) ordering wave vector at

Q = (0.5, 0.5) in the ab-plane. Direct coupling between the

superconducting phase and the resonance excitation has

been observed through the mode’s complete disappearance

above Tc in optimally doped-cuprate systems and through

the characteristic frequency of the resonance mode being

directly proportionally to Tc. This intimate link between the

energy scale of the superconducting phase and that of the

resonance mode, ER = 5.8 kBTc, along with the resonance

mode’s universal presence in all classes of high-Tc cuprates,

has led to speculation that the resonance is intimately

related to electron pairing and superconductivity.

To demonstrate that the resonance mode is indeed

related to the electron-electron pairing process in the

high-Tc cuprates, an experimental signature must be

established that shows a definitive coupling between the

resonance mode and the quasiparticle behavior within the

superconducting phase. At moderate field strengths, a c-axis

aligned magnetic field introduces vortices into the CuO2

planes of the cuprates and weakens the superconducting

state. Once the field strength reaches above the upper

critical field (Hc2) of the system, the nonsuperconducting

vortex regions prevent the establishment of a coherent

superconducting phase. Thus, through comparison of the

magnetic field behavior of the quasiparticle excitations

observed via heat capacity measurements with inelastic

neutron measurements of the resonance mode, possible

links between quasiparticle behavior and the resonance

can be investigated. In fact, previous measurements on the

hole-doped YBa2Cu3O6.6 (YBCO6.6) system have attempted

such a study by demonstrating that the resonance mode

is partially suppressed under the application of a c-axis

aligned magnetic field in a fashion similar to the measured

condensation energy [2]. While these results suggest a

1University of Tennessee, Knoxville, TN 37996

2NIST Center for Neutron Research, National Institute of Standards 

and Technology, Gaithersburg, MD 20899

3National Laboratory for Superconductivity, Chinese Institute of Physics, 

Beijing, China

4Institute Laue-Langevin, Grenoble, France

5Hahn-Meitner Institut, Berlin, Germany

FIGURE 1: a) BT-9 momentum scans through the Q = (0.5, 0.5) in-plane 

AF ordering wave vector at the resonance energy in PLCCO, ∆E = 10 meV.

The enhancement observed upon cooling into the superconducting 

phase (yellow shaded region) at (0.5, 0.5) is indicative of the resonance 

mode. b) 7 T (≈ μ0HC2) momentum scans through Q = (0.5, 0.5) at the

resonance energy. The resonance mode has completely vanished under 

this field strength. c) Schematic of S(Q, ω) versus energy at T = 2 K at the 

AF ordering wave vector for PLCCO under both 0 T and 7 T. Upon the 

application of a superconductivity-suppressing field, quasi-2D AF order 

is stabilized, and the resonance mode is completely suppressed.

18
NCNR 2007 ACCOMPLISHMENTS AND OPPORTUNITIES

References

[1] S. Wilson et al., Proceedings of the National Academy of

Sciences 104, 15259 (2007).

[2] P. Dai, H. A. Mook, G. Aeppli, S. M. Hayden, and F. Dogan,

Nature 406, 965 (2000).

[3] S. Wilson et al., Nature 442, 59 (2006).

[4] H. J. Kang et al., Phys.  Rev. B. 71, 214512 (2005)

link between the resonance mode and the quasiparticle

excitations measured through specific heat, the

experiments were unable to completely suppress Tc and the

corresponding condensation energy due to the extremely

high Hc2’s manifested by all of the hole-doped cuprates.

Fortunately, for the electron-doped cuprates the upper

critical fields are substantially lower than their hole-doped

counterparts, and the magnetic resonance mode has very

recently been observed in these systems [3]. This discovery,

along with the advantageous feature of an experimentally

accessible Hc2, now enables a study of the detailed evolution

of the resonance mode as superconductivity is driven into its

field suppressed ground state. Specifically, we have chosen

to study the c-axis aligned magnetic field dependence of

the resonance in the optimally-doped Pr.88LaCe.12CuO4-δ

(PLCCO Tc = 24 K) cuprate system.

Our results are shown in Fig. 1 a-b, where for fields greater

than Hc2 we find that the resonance excitation completely

vanishes. The upper critical field in this geometry was

determined to be ≈ 7 T through heat capacity measurements

of the superconducting phase transition.

These heat capacity measurements, conducted in parallel

to our neutron efforts, were also able to extract the field

dependence of the superconducting condensation energy,

Uc (Fig. 2b). Overplotting the relative field dependence

of Uc and the resonance mode in Fig. 2a reveals that the

resonance mode’s rapid suppression as a function of

field closely follows the suppression of Uc in PLCCO. The

relative spectral weight of the resonance is therefore

directly related to the quasiparticles participating in the

superconducting condensate.

Our magnetic field experiments have also revealed the

emergence of a competing AF phase with the suppression

of superconductivity. Previous experiments on underdoped

PLCCO concentrations (Tc < 23 K) have already

demonstrated that a quasi-two dimensional AF state coexists

with superconductivity, whereas for optimally doped PLCCO

(Tc > 23 K) concentrations no zero field static magnetic

order exists [4]. A direct competition between this quasi-2D

AF phase in underdoped samples and superconductivity

was shown through an enhancement in the coexisting AF

phase upon the application of a c-axis aligned magnetic

field. This competition, however, was only observed

in underdoped systems in which the AF phase already

coexisted with SC under zero field. Indeed, previous studies

on optimally doped PLCCO concentrations were unable

to resolve the appearance of any field-induced competing

AF phase in samples which initially possessed no AF order

(perhaps due to small signal or insufficient sample mass).

Our neutron studies of the present optimally doped system

have now shown the clear appearance of a field-induced

quasi-two dimensional AF phase. The induced AF magnetic

signal exhibits an anisotropic response with respect the

applied field direction with no observable order induced

under the application of a magnetic field parallel to CuO2

planes. This is a clear indication that the induced AF signal

arises through a direct competition with the SC phase

(which is strongly suppressed when the field is oriented

parallel to c-axis while only slightly affected when the

field is parallel to the ab-plane). This behavior is strikingly

similar to the competition between the SC phase and the

incommensurate spin density wave state in the La2-xSrxCuO4

(LSCO) hole-doped system, thereby suggesting that the

presence of a competing magnetic phase coexisting with SC

is a common feature of the cuprates.

Through our high-field neutron studies of the static

order, low energy excitations, and resonance mode in the

PLCCO, we have mapped out a comprehensive picture

of the modification of the spin behavior in a cuprate

superconductor as it is driven into its field suppressed,

non-superconducting groundstate (Fig. 1c). Our results

show that the spectral weight of the resonance in PLCCO

is directly connected to the system’s condensation energy,

with the resonance mode vanishing entirely with the fieldsuppression of the superconducting phase. Even more

intriguing is the apparent observation of the transfer of

spectral weight from the suppressed resonance mode into

a newly stabilized AF phase under field. However, future

experiments are required to quantitatively test this. The

picture through which the spin excitations and static

magnetic order in the cuprates evolve as these systems

are driven to be nonsuperconducting provides invaluable

insight into the detailed nature of the ground state from

which high-Tc manifests itself. The present work has taken a

fundamental step toward forming this picture by providing

a comprehensive study of the magnetism in the field

suppressed ground state of PLCCO.

FIGURE 2: a) Field dependence of the condensation energy, Uc, (in blue 

symbols) overplotted with the field dependence of the resonance 

mode in PLCCO. The resonance mode completely disappears by 7 T 

coincident with the vanishing of the condensation energy. b) Temperature dependence of Uc under various fields. The magnetic field was 

applied along the perpendicular to the CuO2 planes.

19
Interfacial Domain Walls in Perpendicular

Magnetic-Media Prototypes

S. M. Watson, J. A. Borchers1; T. Hauet2; S. Mangin, F. Montaigne3; E. E. Fullerton4

Condensed Matter

1Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899

2Hitachi Global Storage Technology, San Jose, CA 95135, USA

3LPM, Nancy University-CNRS, Vandoeuvre-les-Nancy Cedex, France

4University of California, San Diego La Jolla, CA 92093-0401 San Diego La Jolla, CA 92093-0401

FIGURE 1: Comparison of magnetization vs applied field for films with 

Pd thicknesses of 0.5 nm and 0.7 nm taken at 300 K. The black arrows 

indicate the direction of the field sweep. The red oval highlights the 

gradual decrease in magnetization suggestive of the formation of a 

domain wall lying in the layer plane. The cartoons illustrate the behavior 

of selected Co moments (red) and the TbFeCo moment (blue) at various 

fields. The question mark in the cartoon indicates uncertain behavior in 

the layer neighboring TbFeCo, also shown in Fig. 3.

The advancement of computer technology and handhelddigital devices has created a continuous demand for

increased magnetic storage capacity. Traditional storage

media has magnetic moments oriented in the film plane

while in the newest “perpendicular” media information

is stored in bits with magnetic moments oriented out of

the plane. These multilayer films consist of a magnetically

anisotropic (“hard”) top layer over a more isotropic

structured “soft” underlayer that returns the flux, but also

plays several important roles in the design of the write

head and read head. These innovations have led to a large

increase in the density of stored bits to ≈ 40 Gbit/cm2

(250 Gbit/in2) with a limit projected eventually to reach

1000 Gbit/in2. Perpendicular media, in which a single bit is

comprised of a single domain, may allow for the lateral size

constraints necessary to achieve this long term goal.

Studies of exchange-spring systems have shown that the

exchange coupling between the hard and soft magnetic

layers leads to the formation of a magnetic spiral during

field reversal [1,2]. The system’s transport properties

depend upon the characteristics of these spiral domain walls,

as demonstrated by magnetoresistance measurements (i.e.,

field-dependent resistance) that show pronounced features

varying with the width of the spiral domain wall [3]. While

depth-dependence of spirals can be directly probed using

polarized neutron reflectivity in systems having in-plane

moments, the out-of-plane moments can be probed only

indirectly, since the scattering vector and the measurement

direction are parallel in that case. Here we highlight our

reflectivity studies that utilize a novel scattering geometry

in order to extract the magnetic moment component in

the film plane as a function of depth. This method obtains

information on the field-dependent evolution of the inplane domain wall.

To probe the field dependence of the magnetic moment

reversal, we have used Polarized Neutron Reflectometry

(PNR) with the incident neutron polarization perpendicular

to the sample surface. This arrangement permits

investigation of magnetic properties of an exchange-coupled

bilayer system with out-of-plane magnetization. Using

Tb55Fe142Co37 (25 nm)/[Co (0.42 nm)/Pd (x)]15

(x = 0.5, 0.7 nm) structures grown at room temperature on

Si wafers by dc magnetron sputtering, we were able to study

the evolution of the domain wall as a function of the Pd

thickness. In this system, the moment configuration results

from the competition among the applied magnetic field,

short-range ferromagnetic (FM) exchange coupling between

the Co layers, antiferromagnetic (AF) exchange coupling

between the TbFeCo and neighboring Co layer, and longrange dipolar interactions. In addition, both the [Co/Pd]

bilayers and TbFeCo exhibit strong out-of-plane anisotropy.

As a preliminary investigation, we measured the magnetic

hysteresis curves of two films having different Pd thicknesses

(Fig. 1). After saturation of all the layer moments in a high

field, the first reversal occurs before reaching negative fields

because of the strong AF coupling of the CoPd layers to the

TbFeCo base. Note that the thinner Pd-separator sample

(x = 0.5 nm) flips before the thicker one: as expected, the

exchange coupling between Co layers is larger for a thinner

Pd separator, and the AF coupling to the layer near the base

dominates. Thus the magnitude of the exchange coupling

between the Co layers may be tuned by changing the Pd

thickness. Also note the gradual decrease in magnetization

before the flip, which suggests that a gradual moment

reversal, a domain wall, is developing through the layers.

20
NCNR 2007 ACCOMPLISHMENTS AND OPPORTUNITIES

References

[1] D. C. Crew and R. L. Stamps, J. Appl. Phys. 93 (10), 6483 (2003).

[2] G. Asti et al., Phys. Rev. B 73, 094406 (2006).

[3] S. Mangin et al., J. Appl. Phys. 89 (11), 7203 (2001).

To reproduce the conditions for the magnetization

measurements (Fig. 1), PNR data were obtained at a series

of fields at room temperature. For the PNR experiments,

both the neutron polarization and the external field were

oriented perpendicular to the sample plane, parallel to

the direction of the scattering vector Q. There are four

reflectivity cross-sections: R+ + and R− − labeled non-spin

flip (NSF) as the neutron retains its original polarization,

and R+ – and R– +, labeled spin flip (SF), where the neutron

spin rotates 180°. In the new geometry, NSF reflectivity is

sensitive to the chemical composition of the film, such as

layer thicknesses and interfacial roughnesses. SF reflectivity

is sensitive only to the component of the magnetization

projected in the sample plane, i.e., perpendicular to the

field direction. To obtain the chemical and magnetic profile

as a function of depth, the PNR data were fitted using a

least squares optimization. To reduce the number of free

parameters, fits of the structural parameters from x-ray

reflectivity data were applied to the neutron data and held

constant while select neutron parameters were allowed to

vary restrictively.

The field dependence of the spin-flip reflectivity data for

films with Pd thicknesses of 0.5 nm and 0.7 nm is shown

in Fig. 2. Qualitatively, an increase in spin-flip reflectivity

magnitude is observed with decreasing field and shows a

dependence overall on Pd thickness. As the field decreases

from 0.7 T (near saturation), the observed increase in the

scattering indicates that the in-plane component of the

moment (and thus the in-plane projection of the domain

wall) is growing. At 0.005 T, where we expect antiparallel

alignment of the Co layers to the TbFeCo base, the SF

reflectivity drops off as the in-plane moments are again

reduced, with the Co and TbFeCo magnetic moments then

aligned perpendicular to the film plane: i.e. the domain wall

has collapsed.

Figure 3 summarizes the results. Left to right, the cartoon

displays the domain wall originating at the top surface, with

the Co layer moment parallel to the field, and extending

to the layer near the TbFeCo interface, with moments

gradually tipping away from the field. At this interface (i.e.,

Co layer number 15), the in-plane moment component

changes abruptly, presumably due to the competition

between the field and the strong, local AF coupling between

the Co and TbFeCo base. The figure also

illustrates that the in-plane projection of

the moment increases in magnitude with

decreasing field as expected because the

AF coupling should gradually overcome the

torque of the applied field.

In conclusion, PNR results confirm the

formation of an in-plane domain wall

as indicated by the magnetization and

magnetoresistance measurements. The

extent and depth of the domain wall vary

with the exchange stiffness of the Co-Co

interaction of the Co/Pd bilayers and with

the applied field. Further, we were able to

isolate the field-dependence of the domain

wall spiral using a novel measurement

geometry. Though neutron reflectivity

measurements are not directly sensitive

to moments perpendicular to the sample plane, this

new configuration provides a means to indirectly gather

information on the out-of-plane moment component. Our

results thus open the door for future investigations of the

depth-dependent magnetic structure in perpendicular

recording media.

FIGURE 3: Moment angle vs CoPd layer number for various applied 

fields. At lower fields, the moment projects more into the plane. The 

magnetic behavior in layer 15 is uncertain, presumably due to inhomogeneity of the magnetization across the sample plane. The green line 

indicates a 1.4 nm layer at the TbFeCo/Co interface in which the moment reverses direction to line up with the net moment in the TbFeCo 

(grey) region which is aligned with the applied field.

FIGURE 2: Comparison of the average spin-flip reflectivity data for films with Pd thicknesses 

of 0.5 nm (left) and 0.7 nm (right). The increase in SF reflectivity at intermediate fields corresponds to in-plane moments, consistent with domain wall formation.

21
Discovery of Zone Boundary Soft Modes

in the Relaxor Ferroelectric PMN

I. P. Swainson1; C. K. D. Stock2; P. M. Gehring3; G. Xu4; H. Luo5

Condensed Matter

Piezoelectrics are solids that have the ability to convertmechanical energy into electrical energy and viceversa. When a piezoelectric crystal is squeezed, a voltage

is generated across the opposite faces of the crystal. When

an external voltage is applied, the crystal dimensions

distort. This effect is extremely important, finding use in

sonar, ultrasound imaging, microphones, and computer

hard drives. The lead oxide perovskites Pb(Mg1/3Nb2/3)O3

(PMN) and Pb(Zn1/3Nb2/3)O3 (PZN) belong to a novel

class of materials known as “relaxors” that possess ultrahigh

piezoelectric properties that far surpass those of

PbZrxTi1-xO3 (PZT) ceramics, which have long been the

material of choice for use in commercial devices. When

either PMN or PZN is combined with small amounts

of PbTiO3, which is a conventional ferroelectric, the

piezoelectric properties are enhanced to record-setting

levels, making these materials enormously attractive for

industrial, medical, and military applications. But beyond

a certain level of PbTiO3 the piezoelectric properties

drop precipitously [1]. While different ideas have been

proposed to explain these anomalous relaxor properties,

no consensus exists.

Pure PMN and PbTiO3 share many static and dynamic

features. Of particular note is the fact that both exhibit a

low-frequency, transverse optic (TO) soft phonon at the

zone center [2], which in the case of PbTiO3 drives the

cubic-to-tetragonal ferroelectric transition at 763 K. While

the TO mode in PbTiO3 never softens completely because

the transition is first order, PMN exhibits no such transition,

retaining an average cubic unit cell down to 4 K; instead,

the TO phonon in PMN becomes extremely broad in energy

on cooling from 900 K. A simultaneous broadening of the

transverse acoustic (TA) phonon in PMN that tracks that of

the TO phonon is also observed upon cooling. Intriguingly,

the damping of both phonons vanishes near the nominal

Vogel-Fulcher freezing temperature Tf ≈ 220 K. Also

intriguing is the fact that the TO phonon frequency in PMN

increases with cooling below Tf in a manner consistent with

that expected for a conventional ferroelectric.

To further our understanding of the complex lattice

dynamics of relaxor materials, measurements were made on

a large (8 cm3) single crystal specimen of the prototypical

relaxor PMN at 300 K and 600 K over a broad region of

reciprocal space using the neutron time-of-flight scattering

technique. The PMN crystal was oriented in the [HHL]

zone and mounted inside a closed-cycle 4He refrigerator

with access to temperatures from 30 K to 650 K. The neutron

scattering measurements were performed on the NCNR Disk

Chopper Spectrometer to characterize the low-frequency

lattice dynamics along the major symmetry directions Γ−Λ−R,

Γ −Σ−M, and Γ −∆−X (see the inset of Fig. 1)

Fig. 1 shows an intensity map of the neutron inelastic

scattering measured at 300 K along the reciprocal lattice

direction [1.5 1.5 L], corresponding to a scan along the

transect M-T-R edge of the Brillouin zone. These data reveal

a truly remarkable feature that is indicated by the strong

“column” of inelastic scattering located at the M-point

zone boundary at (1.5 1.5 -1), which extends all the way

from -5 meV to the elastic line. Similar, but weaker, columns

of inelastic scattering are visible at R-point zone boundary

locations as well, such as (1.5 1.5 -0.5). The excitations at

both the R and M-points are well defined in momentum, but

also extremely broad in energy, indicating a highly periodic

form of disorder. At 600 K the intensities of all columns

weaken considerably; this behavior strongly implies the

presence of soft zone boundary modes that are most likely

the origin of the temperature-dependent superlattice peaks

1Chalk River Labs, Chalk River, Ontario K0J 1J0, Canada

2Johns Hopkins University, Baltimore, MD 21218

3NIST Center for Neutron Research, National Institute of Standards 

and Technology, Gaithersburg, MD 20899

4Brookhaven National Laboratory, Upton, NY 11973-5000

5Shanghai Institute of Ceramics, Chinese Academy of Sciences, 

Shanghai, China 201800

22

FIGURE 1: Neutron scattering intensity map measured on DCS 

at 300 K on a single crystal of PMN. The figure is a slice along

[1.5 1.5 L] and shows a continuous dispersion between the M and 

R-points along T. Note the strong continua of inelastic scattering that 

extend to the elastic position from the M-point modes and the weaker 

continua located at the R-points. The curve is a guide to the eye. 

Inset: Brillouin zone (BZ) of the primitive cubic form of the perovskite 

PMN, along with some high-symmetry points and lines. The one 

symmetrically-distinct edge along M-T-R is shown in red. 
NCNR 2007 ACCOMPLISHMENTS AND OPPORTUNITIES

References

[1] S.-E. Park and T. R. Shrout, J. Appl. Phys. 82, 1804 (1997).

[2] G. Shirane, J. D. Axe, J. Harada, and J. P. Remeika, Phys. Rev. B

2, 155 (1970); P. M. Gehring, S. Wakimoto, Z.-G. Ye, and G. Shirane,

Phys. Rev. Lett. 87, 277601 (2001).

[3] A. Tkachuk and H. Chen, AIP. American Institute of Physics

Conference Proc., edited by Peter K. Davies and David J. Singh, Williamsburg, VA, 677, p. 55 (2003).

[4] A. Tkachuk and P. M. Gehring, in preparation.

FIGURE 2: Elastic scattering intensity profiles measured at the M-point 1/2(3 3 0) 

with thermal neutrons along [001] from 10 K to 250 K. The abbreviation r.l.u. stands 

for reciprocal lattice units. The inset shows the temperature dependence of the 

L-integrated intensities at 1/2(3 3 0) (filled circles) on cooling and at the symmetry 

equivalent peak 1⁄2(-3 -3 0) (open circles) on heating. The Vogel-Fulcher freezing 

temperature Tf is indicated by the vertical dotted line.

that have been observed in both x-ray [3] and neutron

measurements, as shown in Fig. 2 [4]. Such zone

boundary soft modes have never been reported in any

relaxor material before.

The data in Fig. 1 demonstrate continuity along the line

M-T-R thus implying that the scattering intensities visible

at the M and R-point zone boundaries have a common

origin. The fact that the modes at M and R appear to be

zone boundary acoustical ones would seem to indicate

that these are the well-known oxygen octahedral tilt

modes. However, preliminary neutron structure factor

calculations suggest that the corresponding ionic

displacements instead involve the Mg/Nb and Pb

atoms. This picture is consistent with prior x-ray studies

according to which the superlattice peaks are created by

anti-parallel Pb displacements correlated along <110>

cubic directions [3]; moreover, neutron data show that

in-phase oxygen octahedra rotations, to which x-rays are

much less sensitive, do not contribute to the intensities

of peaks of the form 1⁄2(h h 0). Further analysis is being

done to identify the eigenvectors associated with these

modes.

Based on the ionic displacements and the broad

linewidths, the superlattice peaks are believed to

represent antiferrodistortive nanoregions roughly 3 nm in

size. X-ray measurements have also demonstrated that the

onset of the superlattice peak intensity occurs at the

Vogel-Fulcher freezing temperature Tf [3]. This establishes

a direct connection between the macroscopic dielectric

properties and local crystal structure of PMN. The potential

relationship between the columns of inelastic scattering

and the superlattice peaks in PMN is therefore intriguing

because the temperature dependence of the M-point

superlattice peak shown in Fig. 2 nearly tracks that of the

zone center soft optic mode [2], which is associated with

the development of short-range ferroelectric correlations at

low temperatures. PMN is also well-known to develop local

regions of ferroelectric order known as polar nanoregions at

high temperature that give rise to strong diffuse scattering

around various Bragg peaks. The presence of both

ferroelectric and antiferrodistortive nanoregions, both of

which exhibit correlations of roughly 3 nm to 5 nm, suggests

a complex interplay between these competing orders that

may explain the unusual relaxor properties of PMN.

The discovery of strong columns of inelastic scattering

located at the M and R-point zone boundaries in PMN is

significant because it implies a dynamical origin to the

superlattice peaks, which exhibit a temperature dependence

consistent with macroscopic dielectric properties. Of equal

significance is the fact that these columns of inelastic

scattering are not observed in either PbTiO3 or in PMN

doped with a mole fraction of 60 % PbTiO3, both of which

possess tetragonal, ferroelectric ground states with markedly

smaller piezoelectric properties. While not well understood,

the relaxor properties of PMN are believed to stem from

random fields associated with the structural disorder of the

perovskite B-site that is shared by the heterovalent ions Mg2+

and Nb5+. Quenched random fields likely give rise to an

unusually anharmonic free energy surface for which higher

order expansion terms are significant, thereby admitting

many different polar phases. If the free energy surface is

sufficiently flat along directions that connect these phases,

then the huge piezoelectric properties can be understood

by the ease with which the system can be switched between

states of different polar order. The neutron data support

such a picture inasmuch as the coexistence of soft modes

at multiple zone boundaries and the zone center, and the

coexistence of short-range ordered regions of ferroelectric

and antiferrodistortive character, imply that PMN lies

energetically close to states with competing polar order

such that the application of a small external voltage could

produce the observed ultrahigh piezoelectric reponse.

23
Hidden Order in URu2Si2

J. A. Janik, C. R. Wiebe1; G. J. MacDougall, G. M. Luke2; J. D. Garrett3; H. D. Zhou, Y.-J. Jo, 

L. Balicas4; Y. Qiu, J. R. D. Copley5; Z. Yamani, W. J. L. Buyers6

Condensed Matter

The unique properties of correlated electronmaterials, such as high-temperature superconductors,

geometrically frustrated magnetic oxides and low

dimensional magnets, arise from many-body effects which

are poorly understood. Heavy-fermion metals – materials

that have high effective electron masses due to these effects

– display a variety of exotic properties ranging from unusual

magnetism, unconventional superconductivity and ‘hidden’

order parameters. The heavy-fermion URu­­2Si2, wh

becomes superconducting at Tc = 1.3 K at ambient pressure

and zero magnetic field, exhibits a ‘hidden-order’ (HO)

phase starting well above this at an ordering temperature

T0 = 17.5 K, but well below the ‘coherence temperature’

(≈ 70 K) for the formation of heavy-fermion excitations.

The central issue in URu­­2Si2 concerns the identificat

of the order parameter that explains the reduction in

the specific heat coefficient, γ = C/T, and thus the drop

in entropy through the transition at T0. Earlier neutron

scattering measurements indicated that the ordered

moment is 0.03μB, much too small to account for this change.

Here we highlight NCNR Disk Chopper Spectrometer

measurements uncovering a new piece of this puzzle that

accounts for a significant portion of the entropy change.

We carried out experiments above and below the ordering

temperature to measure how the spin excitations evolve.

Figure 1 shows the excitation spectrum in the [H 0 0] plane

of URu­­2Si2 at 1.5 K, well below T0. Note the characteris

gaps of 2 meV at the AF zone center [1 0 0] and 4 meV at

the incommensurate wavevectors [0.6 0 0] and [1.4 0 0]. The

incommensurate wavevector corresponds to a displacement

of 0.4a∗ from the AF zone centers (that is, where

(H + K + L) is an odd integer, and is thus forbidden in the

body-centered cubic chemical structure.) It is clear from

our data (shown in Fig. 2) that above T0 the spectrum is

dominated by fast, itinerant-like spin excitations emanating

from these incommensurate wavevectors. From the group

velocity and temperature dependence of these modes, we

surmise that these are heavy-quasiparticle excitations that

form below the coherence temperature and play a crucial

role in the formation of the heavy-fermion and HO states.

These excitations have a structure in reciprocal space such

that they occur at several symmetry-related wavevectors

within the first Brillouin zone. The amount of phase space

occupied by these excitations is greater than those at the

[1 0 0] AF zone center. Figure 2 shows constant energy cuts

of the excitations in the [H 0 L] plane to emphasize this. At

T = 20 K note the weak AF fluctuations at [1 0 0] and [2 0 1]

in comparison with the excitations at the incommensurate

positions. Also, note how a cone of scattering develops at

the incommensurate positions, whereas the AF zone center

simply decreases in intensity as energy transfer is increased.

The results at 20 K suggest a continuum of excitations within a

cone of scattering (as expected for low-lying excitations at the

Fermi surface), as opposed to the sharp excitations that are

gapped below 17.5 K, shown for comparison in Fig. 2a at 1.5 K.

It is the opening of an energy gap in these incommensurate

heavy-quasiparticle excitations as they fall into a condensate

below T0 which makes them less accessible to thermal

fluctuations. This accounts for a significant portion of the

reduction in entropy below the specific heat jump-like

anomaly at 17.5 K, as described in Fig. 3.

1Florida State University, Tallahassee, FL 32306 and

National High Magnetic Field Laboratory, Tallahassee, FL 32310

2McMaster University, Hamilton, Ontario L8S 4M1, Canada

3Brockhouse Institute for Materials Research, McMaster University, Hamilton, 

Ontario L8S 4M1, Canada

4National High Magnetic Field Laboratory, Florida State University, 

Tallahassee, FL 32310

5NIST Center for Neutron Research, National Institute of Standards and 

Technology, Gaithersburg, MD 20899

6Chalk River Labs, Chalk River, Ontario K0J 1J0, Canada

FIGURE 1: Inelastic neutron scattering of URu2Si2 showing the excitation 

spectrum in the [H 0 0] plane at T = 1.5 K (where H and L are integers 

multiplying reciprocal lattice vectors a∗ and c∗; L is integrated from 

−0.12 to 0.12). Note the minimum at the AF zone center [1 0 0] and at 

the incommensurate positions [1±0.4 0 0]. The feature at [2 0 0] is due 

to phonons. The inset shows the intensity obtained by counting at the 

point [0.6 0 0] at 0.25 meV energy transfer on a triple-axis spectrometer 

and demonstrates the development of a gap in the incommensurate 

excitations through the transition. The error bars are determined by the 

square root of the intensity.

24
NCNR 2007 ACCOMPLISHMENTS AND OPPORTUNITIES

References

[1] C. R. Wiebe, et al., Nature Physics 3, 1 (2007).

[2] Z. Fisk, et al., Science 239, 33 (1988).

[3] C. Broholm, et al. Phys. Rev. B 43, 12809 (1991).

[4] C. R. Wiebe, et al., Phys. Rev. B 69, 132418 (2004).

[5] H. Chou, et al., Phys. Rev. B 43, 5554 (1991).

FIGURE 2: Energy cuts in the [H 0 L] plane showing the evolution of 

inelastic scattering in URu2Si2: below T0 at 1.5 K in (a), and above T0 at 

20 K in (b) to (d). The rings at [2 0 0] correspond to phonons. The rings 

marked “SW” at 1.5 K centered on (H + K + L) = odd integers (AF zone 

centers) are spin waves. Note the rings marked “IN” centered at incommensurate points separated by 0.4a∗

 from the AF zone centers in all 

panels. While there are weak overdamped AF fluctuations at the zone 

centers at 20 K, it is clear that at the incommensurate positions cones of 

highly correlated excitations develop as a function of energy. Comparing (c) with (a), the incommensurate excitations in the same energy cut 

display a ring, i.e., have a smaller group velocity, below T0 than above 

where they display a cone.

The implications of our work are as follows: (1) the

incommensurate excitations have a well-defined structure as

a function of Q, and thus the electrons are highly correlated

above 17.5 K. This is completely unexpected for a system of

localized moments in a paramagnetic state, but is similar to

dynamics above the Néel temperature, TN, that have been

observed with neutron scattering in other itinerant electron

systems such as chromium and V2O3. (2) The dispersion is

such that the maximum group velocity is at least a factor

of two larger than the maximum group velocity of the

excitations in the HO state. A significant restructuring of

the Fermi surface must be responsible for the HO state. (3)

The energy gap in these strong spin fluctuations opening

up below 17.5 K must provide a considerable portion of the

entropy removal at the transition.

Our findings place constraints on all new theories of

HO in URu­­2Si2. A minimum theory must account 

(1) incommensurate itinerant spin excitations and

(2) the lack of crystalline electric fields up to 10 meV. The

HO transition seems to be a rearrangement of electrons

at the Fermi surface in an itinerant rather than localized

electron picture. Excitations out of this state at these

incommensurate wavevectors show a mode-softening

that is reminiscent of another dynamic ground state

that has no translational order but a prominent specificheat anomaly—the superfluid liquid helium transition.

Correlations between the heavy quasiparticles in URu­­2

build up below 100 K, and at 17.5 K, there is a transition to

a new condensate that remains unidentified. The true order

parameter for this system has yet to be determined.

FIGURE 3: Correlations with features in the specific heat. (a) and (b), cuts 

in the [H 0 L] plane integrated from 5 meV to 8 meV at 20 K in (a), and at 

100 K in (b). The incommensurate scattering at positions such as 

[1.6 0 1] disappears at 100 K (indicated by a circle). This is just above 

the ‘coherence’ temperature where a signature of heavy-quasiparticle 

formation is seen in the specific heat (inset in (c)). (c), the specific heat 

C divided by temperature as a function of T, showing the jump-like 

anomaly at 17.5 K. The linear portion of the specific heat, γ, is calculated 

with the solid line to be 155(5) mJmol−1 K−2. The blue data point is our 

calculation of γ = 220(70) mJ mol−1 K2 from the incommensurate spin 

fluctuations observed at 20 K.

25
Quantum Coherence in a Spin Chain

G. Xu1,2; C. Broholm, Y. Chen, M. Kenzelmann1,3; Y.-A. Soh4; G. Aeppli5; J. F. DiTusa6; C. D. Frost7; 

T. Ito, K. Oka8; H. Takagi8,9

Condensed Matter

Superconductivity spectacularly displays quantum phasecoherence on a macroscopic length scale. Quant

effects are more usually associated with physics on the

atomic scale. Here we report quantum coherence amo

the magnetic dipoles of Ni2+ in crystalline Y2BaNiO5 at

a length scale (hundreds of atoms) being approached

in integrated circuit devices. Using neutrons, we al

demonstrate that the coherence length can be modified

by static and thermally activated defects in a quantitatively

predictable manner. The observation of quantum coherence

beyond the atomic scale in a magnetic material exhibiting

no classical long range order is a surprising first, and betters

prospects for applications in quantum computing.

A perfectly coherent wave is one in which the wave fronts lie

on planes and appear periodically in time. In more compl

waves, coherence is measured over the finite distance (or

time) over which correlations in phase are more or less welldefined. Quantum phase coherence describes the coherence

properties of the wave-function. With quantum coherence

comes all the beauty and mystery of quantum mechanics,

including interference, uncertainty and especially

entanglement, a property central to the development of

quantum computation. Typically, interaction with t

environment limits quantum coherence. The experimental

conditions under which quantum coherence can transcend

the atomic scale and acquire technological importance

remain a major pursuit of applied physics.

Fig. 1A provides experimental evidence that this does 

occur in the one dimensional antiferromagnet Y2BaNiO5.

The sharp intensity ridge is the experimental signature of

coherence: a well defined relationship between the spatial

periodicity (horizontal axis) and temporal periodicity

(vertical axis) in the excited state wave function. To quantify

the degree of coherence, we focus on the lowest energy

excitation marked by an intense red peak in the data.

It corresponds to the creation of a magnon with crystal

momentum q = π through interaction with a neutron.

Fig. 2B shows an energy-cut through the peak obtained

with high resolution on the SPINS spectrometer. The sharp

initial onset sets a limit of 0.1 meV on the relaxation rate

indicating that the wave function remains coherent through

100 periods of its temporal oscillation. The three peaks

result from crystalline anisotropy and finite resolution yields

the high energy tail. The solid symbols in Fig. 2D show the

corresponding fixed energy cut versus q. After accounting

for resolution, the intrinsic peak width is just 0.02 π and this

indicates quantum coherence encompassing up to 100 nickel

1The Johns Hopkins University, Baltimore, MD 21218

2Brookhaven National Laboratory, Upton, NY 11973

3NIST Center for Neutron Research, National Institute of Standards and 

Technology, Gaithersburg, MD 20899

4Dartmouth College, Hanover, NH 03755

5University College London, London, WC1H 0AH, UK

6Louisiana State University, Baton Rouge, LA 70803

7ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX, UK

8National Institute of Advanced Industrial Science and Technology, Tsukuba, 

Ibaraki 305-8562, Japan

9University of Tokyo, Kashiwa, Chiba 277-8561, Japan

FIGURE 1: A: Map of neutron intensity multiplied by energy for 

Y2BaNiO5 at T = 10 K acquired on MAPS at the ISIS facility. B-F: Diagrams 

of quantum order in Y2BaNiO5. The red, white, and blue spheres represent 

sites with spin projection quantum numbers 1, 0 or -1. Impurities are 

represented by black spheres. B: Pure S = 1 chain at T = 0.

C: Magnon excitation; D: at T > 0, thermally excited magnons confine 

each other into boxes. E: Confinement by Ca impurities, which introduce 

holes (small black spheres) into the chain and align neighboring spins. F: 

Confinement by non-magnetic Mg impurities.

26
FIGURE 2: A: T dependence of the q = π magnon energy in Y2BaNiO5. 

Diamonds indicate low T excitation energies in samples with chemical 

impurities at the average spacing indicated by the upper axis. That axis 

shows the calculated thermal defect spacing at the temperature given 

by the lower axis. B: q = π energy scan from SPINS. The solid line is the 

resolution convolved intensity associated with a triplet of magnons 

split by crystalline anisotropy. The gap, ∆, reported in A is the average of

these mode energies. C: T dependence of the classical correlation length 

(open symbols) and the quantum coherence length (closed symbols) 

extracted by fitting data such as those in D and E. Solid and dashed 

lines are theoretical results [1]. D and E: Solid symbols are cuts through 

neutron data for hω = 7.5 meV probing quantum coherence. Red line is 

resolution width. Open symbols indicate energy integrated data (hω > 8 

meV) probing classical correlations. Data are from BT-2 

and BT-4.

NCNR 2007 ACCOMPLISHMENTS AND OPPORTUNITIES

References

[1] G. Xu, et al., www.sciencexpress.org/10.1126/science.1146067.

atoms. Also shown is the equal time correlation length: the

classical distance over which probing one spin also reveals

neighboring spin states.

To employ quantum coherence we must understand its

practical limits, so we examined the effects of thermal and

chemical defects. Fig. 2C shows that the coherence length

decreases precipitously upon heating until it becomes

indistinguishable from the classical correlation length when

the thermal energy matches the gap energy. The solid line

shows the calculated temperature (T) dependent distance

from a random location along the chain to the nearest

thermal or chemical defect, assuming a chemical defect

density consistent with low temperature susceptibility

data and a semi-classical description of magnons.

Encouraged by the excellent agreement, Figs. 1 B-F illustrate

the corresponding interpretation of coherence and its

limitations in Y2BaNiO5. A measurement of the projection

of the Ni2+ dipole moment along any chosen direction has

three possible outcomes. Select a specific direction and

indicate by red white and blue which of the three states is

assumed by each spin. Theory indicates that the ground

state of an antiferromagnetic spin-1 chain consists of

alternating red and blue spheres with white spheres interdispersed at random. The classical correlation length can be

considered a measure of the average spacing between white

spheres. Though such a state appears disordered to the

classical observer (Fig. 1 B), it is in fact a perfectly coherent

quantum state as indicated by our observation of coherent

excitations (Fig. 1A). Fig. 1C indicates the nucleus of an

excitation in the form of a pair of red spheres that propagate

coherently. The finite T and doping experiments indicate that

coherence is limited by scattering from thermally (Fig. 1D) or

chemically (Fig. 1E-F) induced defects.

The experiments described thus far show that heating

and doping limit quantum coherence. Particular to one

dimension is the confining effect of chemical impurities

which according to Heisenberg uncertainty principle

(∆p • ∆x ≥ h/2) should increase kinetic energy (p2/2m

Might the analogy between thermal and chemical impurities

extend to this fundamental quantum effect? Figure 2A shows

the T dependence of the energy, ∆, associated with creatin

a q = π magnon. It is indeed found to increase with T, which

is qualitatively consistent with confinement by thermally

generated defects (Fig. 1D). Moreover, the red points in

Fig. 2A show the corresponding excitation energy in

chemically impure samples at T = 10 K with defect density

given by the upper axis. This axis was chosen in accordance

with the solid line in Fig. 2C so the chemical defect density

matches the thermal defect density corresponding to the

lower axis. Data points from chemically and thermally doped

samples fall on the same line which in turn was obtained

from exact diagonalization of finite length spin chains. We

have thus established that chemically and thermally induced

defects lead to blue shift through confinement.

While quantum spin chains with a gap have a finite

classical correlation length, our experiments show that

the coherence of excited states is limited only by thermal

and chemical disorder. Both effects are accounted for by a

semi-classical theory of magnons scattering from each other

and from chemical defects. The experiments demonstrate

that quantum phase coherence can be achieved in a solid

state magnet at length scales that approach feature sizes

in modern integrated circuits, thus removing one of many

barriers towards applications in quantum computing.

–

–

–

27
Concrete, the most widely used manufactured material, has

moved one step closer to joining the nano revolution that

is reshaping the use of many materials. The most important

binding phase in cement paste, calcium silicate hydrate (CS-H), has a structure at the nanometer scale that is directly

related to concrete properties, but the structure of this phase,

and in particular the composition and density, have proven

remarkably difficult to determine. By combining small angle

neutron and x-ray scattering data, and by exploiting the

hydrogen/deuterium neutron isotope effect with both water

and methanol, we have established the mean formula and

mass density of the nanoscale C-S-H gel particles [1].

The disordered and complex structure of C-S-H, which

includes a nanometer-scale pore system that normally is filled

with water, changes significantly on drying, rendering the

results of most modern techniques the subject of extensive

interpretation. During the last decade the results from a

variety of neutron scattering experiments have shed light on

several characteristics of C-S-H in its normal, water-saturated

state. In particular, small-angle neutron scattering (SANS)

measurements on cement paste indicate that the nanometerscale structure consists of solid particles or “globules” of

The Nanoscale Building Blocks of Concrete

A. J. Allen1; J. J. Thomas, H. M. Jennings2

Engineering Physics

C-S-H that are packed randomly to form a continuous phase

through the paste, binding the cement particles together.

The globules and associated water are shown schematically

in Fig. 1a (striped images). Much has been learned [2-4],

including the characteristic size of the globules (4 nm to 5

nm), their fractal arrangement and packing density, and the

specific surface area of the paste. In addition, quasi-elastic

neutron scattering (QENS) measurements have determined

the relative amounts of chemically bound, adsorbed, and

liquid water within hydrated cement paste [5]. What was not

known until quite recently [1] is the water content and mass

density of the solid C-S-H globules, the basic building blocks

of the hydrated microstructure.

SANS is ideal for investigating the nanostructure of disordered wet materials such as cement paste. The intensity of

the scattering at a given scattering vector, Q, depends on the

amount of structure in the associated size range, but is also

directly proportional to the square of the difference in the

neutron scattering length densities (SLD) of the scattering

phases, a factor called the scattering contrast. If the chemical composition and mass density of both phases are known,

the contrast can be calculated precisely. This is not the

case for the C-S-H phase in cement, however: the unknown

water content and density of solid C-S-H is a longstanding

issue of importance in cement science that also hinders a

full interpretation of scattering data. The problem of an

unknown solid phase can often be solved by varying the SLD

of the liquid phase by replacing it with a deuterated fluid, in

this case by exchanging the pore H2O with varying amounts

of D2O (heavy water), which has a much higher SLD. By

noting the matchpoint where the contrast drops to zero,

the solid SLD and solid-H2O contrast can in principle be

calculated directly.

Two problems with this approach arise for cement-based

materials. The presence of a small amount of nanoscale

Ca(OH)2 intermixed with C-S-H means that a zero-intensity

contrast matchpoint does not exist, since Ca(OH)2 has a

matchpoint quite different from that of C-S-H. More important, solid C-S-H undergoes full H/D exchange to become

C-S-D (see Fig. 1b), adding an additional level of complexity.

The volume fraction of Ca(OH)2 in various types of cement

paste can be determined by analyzing the contrast variation

parabolas (plotted as curves of scattered intensity versus D2O

fraction). The scattering contribution from Ca(OH)2 can

then be subtracted, leaving a self-consistent C-S-H contrast

curve for H2O/D2O contrast experiments. The problem now

is that this curve is actually for C-S-H/D as D exchanges for

H, where both the solid and liquid SLD are changing, and

1Ceramics Division, National Institute of Standards and Technology, Gaithersburg, MD 20899

2Northwestern University, Evanston, IL 60208

28

FIGURE 1: Schematic diagram of nanoscale hydration product in cement 

paste, consisting of layered C-S-H particles (striped images) and Ca(OH)2

crystals surrounded by pore fluid. Three fluid exchange scenarios are 

shown. Phases containing only hydrogen are blue, while phases containing deuterium are red. The black lines indicate the scattering interface 

between the solid phases and the pore fluid. A) Normal saturated paste 

with H2O in the pores. Due to its small volume fraction, scattering from 

nanoscale Ca(OH)2 is almost negligible compared to that from C-S-H. B) 

A D2O-exchanged paste. The C-S-H exchanges with OD- groups to 

become C-S-D, while the Ca(OH)2 is unchanged. Compared to case A, 

the scattering between Ca(OH)2 and the pore fluid is much stronger, 

while scattering between C-S-D and the pore fluid is much weaker. 

Experiments with D2O exchange allow the volume fraction of nanoscale 

Ca(OH)2 to be determined. C) A paste exchanged with d3-methanol 

(CD3OH). Since the fluid does not contain OD- groups, only the pore 

phase changes. Both C-S-H and Ca(OH)2 scatter strongly with CD3OH and 

the scattering length density of the overall C-S-H/ Ca(OH)2 nanoscale 

solid phase can be determined. By combining this result with the 

Ca(OH)2 volume fraction obtained from D2O exchange (Case B), and with 

SAXS data, the neutron and X-ray scattering length densities, composition, 

and mass density of the C-S-H phase can be determined.
no unique solution is possible if both the composition and

density of C-S-H are unknown.

Providing constraints that define and refine the scattering length density of C-S-H solves this problem. Important

information is obtained from SANS contrast data using

CH3OH/CD3OH exchange: since CD3OH does not contain

OD groups, the OH groups in solid C-S-H remain OH, and

only the fluid phase exchanges (see Fig. 1c). Thus, the SLD

for the combined C-S-H/Ca(OH)2 nanostructure can be

calculated from the ratio of the SANS intensities in CH3OH

and in CD3OH [1]. Another constraint comes from comparing SANS and small-angle x-ray scattering (SAXS) data from

identical pastes on an absolute-calibrated intensity scale.

Careful experiments of this nature have provided new and

precise information about the important C-S-H phase in cement. While the calcium/silicon (C/S) molar ratio can vary

over a wide range, it is well established at about C/S = 1.7 for

C-S-H formed in normal cement paste. With this ratio held

fixed, the combined SANS contrast and SAXS data provide

an over-determination of the two remaining unknowns to

give a water-to-silicon molar ratio, H/S = 1.80 ± 0.03, 

a physical density of (2.604 ± 0.022) x 103 kg m-3 [1]. 

H/S ratio of 1.80 represents the water content of the C-S-H

particles themselves, and does not include any adsorbed

water outside the particles. This interpretation provides a

framework for reconciling C-S-H water contents obtained by

a variety of different measurements, some of which are quite

different from the value reported here.

In a system with a liquid phase and two solid phases,

adjusting the liquid SLD to match that of one solid

phase, a process known as contrast matching, causes the

scattering from the matched phase to disappear, such

that the measured scattering arises only from the other

solid phase. Such experiments, which also incorporate

data from ultrasmall-angle neutron scattering (USANS),

have enabled the Ca(OH)2 component in cement paste

to be distinguished from the rest of the microstructure,

both in its nanoscale form and in its better-known form as

micrometer-scale crystallites. Applying all of the constraints

allows the SANS (or SAXS) scattering curves for cement to

be decomposed into the constituent components associated

with the C-S-H and Ca(OH)2 microstructures over the

nanometer-to-micrometer scale range, as shown in Fig. 2A,

and then reassembled to predict the overall scattering curves

obtained for different H2O/D2O mixes.

While the SANS and USAXS data have been quantitatively

interpreted using multi-component fractal models

previously, the new information provides a much firmer

basis for the absolute calibration of the microstructural

information obtained. However, the USANS data extends

such calibration up into the tens of micrometer lengthscale. This has been sufficient to apply more conventional

particle size measurement to the Ca(OH)2 component,

and determine, for the first time, the micrometer scale

Ca(OH)2 size distribution, within set cement, on the same

absolute scale as the fractal information obtained at finer

length-scales, as indicated in Fig. 2B.

The nanometer-scale globules of C-S-H are the basic

building blocks of all cementitious materials. Having

established the their composition and density in normal

cement paste, the door is now open to modeling changes

that occur under a host of environmental and mechanical

influences. This is particularly important because new

demands are being placed on this ancient yet irreplaceable

material at an accelerating rate. For examples, one can

look to well-publicized difficulties with the recent massive

tunnel project in Boston, the unique engineering demands

associated with new high-rise buildings with powerful

architectural statements in New York and Chicago, and the

rapidly increasing demand for concrete in Asia caused by

rapid economic growth in those countries. One dark cloud

on the otherwise sunny horizon for concrete is the problem

of CO2 generation during the manufacture of cement. The

carbon footprint of concrete can be lowered significantly by

incorporating industrial byproduct materials such and slag

and fly ash into concrete. Under some conditions this can

be beneficial but it also can cause durability problems. These

materials are known to change the structure, and therefore

the properties, of C-S-H. Here again, building on these

recent results, SANS and other neutron methods can be

used to measure the structure and provide a basis for a new

generation of models.

NCNR 2007 ACCOMPLISHMENTS AND OPPORTUNITIES

FIGURE 2: A) Combined SANS and USANS data for hydrated ordinary 

Portland cement (OPC), the decomposition of the scattering into its 

C-S-H and calcium hydroxide (CH) components, and both fractal and 

particle size fits to the high-Q and low-Q parts of the data as shown. 

B) Micrometer-scale calcium hydroxide crystallite size distribution 

(volume fraction per diameter interval) derived from maximum-entropy 

analysis of the low-Q Ca(OH)2 data component. 

[1] A. J. Allen, J. J. Thomas, and H. M. Jennings, Nature Materials 6,

311 (2007).

[2] A. J. Allen, J. Appl. Cryst. 24, 624 (1991).

[3] J. J. Thomas, H. M. Jennings, A. J. Allen, Cem. Concr. Res. 28,

897 (1998).

[4] H. M. Jennings, J. J. Thomas, J. S. Gevrenov, G. Constantinides,

F.-J. Ulm, Cem. Concr. Res. 37, 329 (2007).

[5] J. J. Thomas, D. A. Neumann, S. A. FitzGerald, R. A. Livingston,

J. Am. Ceram. Soc. 84, 1811 (2001).

References

29
Biaxial Fatigue Failure in Gas Pipelines

T. Gnäupel-Herold1,2; D. Liu1, H. Prask1,2

1NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899

2University of Maryland, College Park, MD 20742

Engineering Physics

FIGURE 1: Residual stress field around the girth weld in an intact pipe 

section. The red and blue boxes indicate the gage sections of the cruciform specimens (I) and (II).

Fatigue has not traditionally been a primary concern inthe design of oil or gas pipelines. However, investigations

of recent oil pipeline ruptures [1, 2] have shown that fatigue

was either the primary or a contributing cause, resulting in

spills > 103 m3 of crude oil. The huge costs associated with

loss and cleanup warrant a more detailed investigation of

material properties and behavior contributing to this type

of failure.

For oil pipelines, vibrations and pressure changes are among

the sources of stress cycling which lead to the high-cycle type

of fatigue at moderate stress amplitudes. Other external

influences that induce fatigue include bending/unbending

during transportation of the pipe sections—identified as the

primary cause for the fatigue rupture of the Enfield Pipeline

[1], wave-action on offshore pipelines, and daily or seasonally

changing soil conditions affecting ground-laid pipelines.

The results are high axial stress amplitudes at relatively few

accumulated cycles.

In pressurized gas pipelines the stresses are always biaxial

with a ratio of hoop to axial stress of 2:1. External forces on

floating structures or from shifting soil will primarily affect

the axial stresses while hoop stresses remain static at a level

determined by the gas pressure. Typical operating pressures

result in hoop stresses of ≈ 70 % of the minimum specified

yield strength (YS), which implies axial stresses of 0.35 × YS.

Thus, infrequent but potentially high amplitude external

stresses add to the already high operating stresses. Such

external stresses are most damaging on pre-existing flaws

or heterogeneities having detrimental properties, such as

residual stress fields at or above the yield strength level.

Residual stress fields of this magnitude occur around

girth welds [3] which are laid in the field during pipeline

installation. This complex “stress environment” exists in the

pipe steel microstructure which is anisotropic (in the axial,

hoop and radial directions) and inhomogeneous (weld

vs. base metal, base metal through thickness), due to the

various stages of rolling, sizing and bending during pipe

manufacture. Neutron diffraction appears uniquely suited

to elucidate this complexity at all points in the pipeline lifecycle, i.e., after welding, to applied biaxial stress, to fatigue,

and to failure, as well as being able to differentiate inside/

outside and weld/base materials.

The specimens used, provided by Dr. Michael Law of the

Australian Nuclear Science and Technology Organization,

were cut from X70 grade steel pipe with a specified minimum

yield strength of 483 MPa and an actual yield strength of

between 543 MPa and 575 MPa. The pipe section used for

electro-discharge-machine cutting cruciform and tensile

specimens was 274 mm in diameter and 120 mm long.

The cruciform gage sections were located such that they

contained two parts: a portion of the weld containing

the root and the heat-affected zone, and a region of high

magnitude residual stress that was located approximately

8 mm to 12 mm away from the weld center line towards the

axial direction. The cruciform specimens were both loaded

statically with 340 MPa in the hoop direction, which loading

was kept constant throughout the experiment. The axial load

was increased until yielding was found using the

d-spacings as a measure, then dropped to 240 MPa and

then increased again which completed one cycle.

Specimen (I) failed in the first cycle at a load of 550 MPa,

well outside the biaxial gage section. The circumstances

of the failure (plastic collapse) and its location at the high

magnitude stress field approximately 10 mm from the weld

(see Fig. 1) prompted a second test with the gage section

to include the location of the fracture of the first specimen.

Specimen (II) had a reduced gage cross section to ensure

the concentration of applied stresses within the gage section.

It accumulated fewer than 50 cycles before failing by brittle

fracture near the edge of the gage section in the heat-affected

zone. Figure 2 shows the lattice-spacings in the center of the

gage section near the outer and the inner pipe surfaces vs.

applied axial stress for specimen (II). At the beginning of

the loading the d-spacings are well distinguished and they

30
NCNR 2007 ACCOMPLISHMENTS AND OPPORTUNITIES

maintain that difference up to the minimum specified

yield strength. Higher stresses cause the d-spacings near

the outside to saturate while the d-spacings near the inner

surface continue to rise in proportion to the applied stress.

This is a clear indication of an earlier onset of yielding near

the outer surface, which was also the region of high tensile

residual stress in the intact pipe (Fig. 1). The yield stress

near the outside of the pipe is estimated to be approximately

50 MPa smaller than near the inside.

The comparison of measurements on this biaxially loaded

sample with a uniaxially loaded (in the axial direction)

tensile specimen reveals the difference between the strength

of the weld and the base materials. The uniaxial specimen

measurement is shown in Fig. 3. Due to the proximity to

the fracture site with its stress concentration in the necki

a more detailed investigation of the transfer of applied

biaxial load into the gage section needs to be conducted.

Different yielding behavior is indicated in the base material

near the inner and outer pipe surface, which is at least a

contributing cause for the failure of cruciform specimen

(I). This finding provides evidence that through-thickness

anisotropy may have to be included in material models for

pipeline simulation. The current practice of using throughthickness average YS results in a slightly overestimated YS for

the region near the outside of the pipe. While these variations

in strength occur well above the minimum specified YS they

may affect the definition of the pipe safety margins. FIGURE 2: Lattice spacings from the gage section of the cruciform 

specimen (II). The inset cartoon shows biaxial tensile stressing of a 

cruciform sample.

[1] National Transportation Safety Board, Rupture of Enbridge Pipeline 

and Release of Crude Oil near Cohasset, Minnesota July 4, 2002, Pipeline

Accident Report NTSB/PAR-04/01, PB2004-916501, Adopted June

23, 2004, Washington, D.C.

[2] Alberta Energy and Utilities Board, Investigation Report: Rainbow 

Pipe Line Company Ltd. Crude Oil Pipeline Failure, October 10, 2006,

www.eub.ca , May 9th 2007.

[3] M. Law, H. J. Prask, V. Luzin, T. Gnaeupel-Herold, Materials

Science and Engineering A 437, 60 (2006).

FIGURE 3: Lattice spacing for an axially loaded tensile specimen, 

measured at four locations near the inside/outside of the weld and 

the base. Base inside/outside positions correspond to inside/outside 

mentioned in Fig. 2. The inset cartoon shows uniaxial stressing of a 

tensile specimen.

References

region, the lattice spacings in the weld continue to climb

because the local stress (> 600 MPa at peak) field is higher

than in the base material. Note that the largest d-spacings

actually occur below the yield region, which is caused

by the experimental regimen of increasing strain rather

than stress. Thus, after the onset of necking, strain is still

accumulated while the applied stress drops. Similar to the

cruciform specimen but at noticeably lower stress levels,

the lattice spacings in the base material saturate (i.e., no

longer increase with stress) first near the outside, while the

d-spacings near the inside continue to climb. This confirms

different yield stresses of the inside/outside locations.

The results presented here reveal that X70 pipe steel

performs well up to the actual yield strength but, as

expected, accumulates a very limited number of cycles at

this stress level. More investigations are needed for cycling

at lower stress amplitudes and especially for axial tension/

compression cycles. The yield stress under biaxial loading

appears to be higher than under uniaxial loading. However,

31
Lateral Roughness Measurements of Buried Interfaces in

Extreme Ultraviolet Lithography Photoresists

K. A. Lavery; V. M. Prabhu; E. K. Lin; W.-L. Wu1; K. W. Choi2; M. Wormington3; S. K. Satija4

Soft Matter/Polymers

1Polymers Division, National Institute of Standards and Technology, Gaithersburg, MD 20899

2Intel Corporation, Santa Clara, CA 95054

3Bede Scientific Inc., Englewood, CO 80112

4NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899

Continual advances in the semiconductor industryhave been driven by the consistent decrease in the

lithographic feature size. As the critical size scale decreases to

the sub-32 nm regime, the presence of roughness along the

feature edge will be a major detriment to quality, reliability,

and the potential for high device performance.

The origins of line edge roughness are not fully understood,

but are rooted in the interdependent exposure, reaction,

and development steps of the photolithographic process. In

particular, the reaction step, in which activated photoacid

molecules catalyze reactions in the exposed regions of the

photoresist, has been linked to roughness formation through

diffusion of acid molecules into unexposed areas. Here

we present the first direct measurement of the complete

photoacid reaction-diffusion front profile in a photoresist

film, combining diffusion length measurements with

examination of the lateral inhomogeneity of the diffusion

front. This measurement was accomplished using specular

and off-specular neutron reflectometry on the Advanced

Neutron Diffractometer/Reflectometer (AND/R) beam line

at the NCNR.

In this work, we used a representative extreme

ultraviolet lithography (EUVL) photoresist

copolymer, polyhydroxystyrene-co-poly(d9-tertbutyl acrylate) (PHOST-co-d9-TBA) where the

hydrogens of the t-butyl protecting group are

replaced with deuterium [1]. This substitution

enhances the neutron contrast between the

protected and deprotected regions of the resist,

as the protecting group is volatile and leaves

the film completely upon deprotection. The

experimental geometry was a polymer-polymer

bilayer [2] supported on a float glass substrate

(Fig. 1A), where the bottom layer was a polymer

containing 6 % by mass of the photoacid

generator triphenylsulfonium perfluorobutane

sulfonate (TPS-PFBS) and the top layer was

the PHOST-co-d9-TBA resist copolymer. This

configuration mimics an ideal, perfectly sharp

exposure line edge, with the bottom layer

representing the exposed regions.

The reaction front was measured using specular

neutron reflectometry (C). Specular neutr

reflectometry was used to determine the extent of

reaction and the diffusion front shape, allowing

insight into the line broadening occurring during the

lithographic process (Fig. 1B). The reflectometry data were

converted into the extent of deprotection as a function of

depth, as shown in Fig. 1C. While these measurements give

the reaction-diffusion front depth profile with nanometer

resolution, specular reflectometry gives no information

on the lateral structure of the reaction front. For instance,

one cannot differentiate a smooth, gradual decay in the

deprotection profile from an undulating, inhomogeneous

reaction front. The ability to discern between these two

scenarios is of critical importance to determining whether

the reaction process is responsible for roughness formation

in lithographic features.

Off-specular neutron reflectometry was used to measure

the buried in-plane structure of the reaction front [3].

Measurements were performed at multiple angles, thus

giving sensitivity to lateral length scales ranging from 90 nm

up to several microns. Off-specular reflectometry offers the

additional advantage of being able to discriminate between

interfacial roughness and material gradients [4]; something

FIGURE 1: A polymer-polymer bilayer is used to model the line edge between the 

exposed and unexposed regions of a photoresist film (A). This geometry is used to follow 

the acid reaction-diffusion front in a model resist system, mimicking the diffusion at an 

exposure line edge (B). 

32
NCNR 2007 ACCOMPLISHMENTS AND OPPORTUNITIES

[1] K. A. Lavery, B. D. Vogt, V. M. Prabhu, E. K. Lin,

W. L. Wu, S. K. Satija, and K. W. Choi, Journal of Vacuum Science

and Technology B 24, 3044 (2006).

[2] E. K. Lin, C. L. Soles, D. L. Goldfarb, B. C. Trinque,

S. D. Burns, R. L. Jones, J. L. Lenhart, M. Angelopoulos,

C. G. Willson, S. K. Satija, and W. L. Wu, Science 297,

372 (2002).

[3] S. K. Sinha, E. B. Sirota, S. Garoff, and H. B. Stanley, Physical

Review B 38, 2297 (1988).

[4] M. Wormington, I. Pape, T. P. A. Hase, B. K. Tanner, and D. K.

Bowen, Philosophical Magazine Letters 74, 211 (1996).

References

that specular measurements are unable to provide. Figure 2

shows an off-specular curve taken at a Qz value of 0.022 Å-1

which illustrates the sensitivity of the scattering intensity

to the lateral form of the reaction front. From specular

measurements, the width of the reaction front is 79 Å. If we

assume that this width is completely due to undulations with

amplitude 79 Å, the calculations overestimate the diffuse

scattering intensity (green curve). On the other hand, if

we assume the reaction front is perfectly smooth and the

reaction front width is due solely to a gradient in the extent

of deprotection, the calculations underestimate the diffuse

scattering (blue curve).

The best fit to the data was obtained when combining these

effects. Assuming the gradient (σG) and roughness (σR)

terms are not coupled, we can constrain the fit using the

interfacial width obtained from specular measurements

(σspec) such that σspec2 = σG

2 + σR2. Using this constraint,

we find the first 75 Å of the reaction front shows a smooth

decrease in the deprotection extent. Over the last 25 Å there

are lateral inhomogeneities at the wave front, modeled as

roughness at the interface. This structure is illustrated in

the red curve in Fig. 2, which provides the best description

of the off-specular data. In addition to separating the

contributions of gradient and roughness, the characteristic

lateral length scale of roughness was found to be on the

order of 800 Å. The amplitude and lateral length scale of

FIGURE 2: Off-specular reflectivity allows the differentiation between different types of “rough” interfaces. Using a highly rough 

interface to describe the reaction front over-estimates the off-specular intensity (green), while a chemical gradient (blue) underestimates the intensity. A chemical gradient with undulations at the wave front provides the best description of the data (red).

the roughness of the reaction front is very smooth with a

very low frequency, characteristics that are acceptable for

next-generation lithography. Any significant roughness

formation is likely to arise from subsequent processing steps

such as the swelling and deswelling that may occur during

the development process. Extending neutron reflectivity

to probe the solid / liquid interface during development

represents the next major step in understanding the

materials limits of chemically amplified photolithography.

33
Nanostructured Liquids From Disordered Surfactant

Melts Blended With Functional Homopolymers

V. R. Tirumala1,2; E. K. Lin2; J. J. Watkins1

1University of Massachusetts, Amherst, MA 01003

2Polymers Division, National Institute of Standards and Technology, Gaithersburg, MD 20899

Soft Matter/Polymers

Block copolymers are immisciblemacromolecules joined together by

covalent bonding which form microscopically

segregated phases. These phases readily form

periodic morphologies that can be controlled

by tailoring the molecular parameters [1].

Recent advances have shown that amphiphilic

(i.e., having water-soluble and water-insoluble

ends) block copolymers can be used in the

templated fabrication of nanostructured

inorganic materials that find a variety of

applications in electronic, magnetic, and

photonic devices. However, microphase

segregated amphiphilic block copolymers

are currently unavailable in bulk quantity,

limiting their utility in the fabrication of

nanostructured inorganic materials at a

commercial scale. On the other hand, low

molar mass amphiphilic surfactants based on

poly (oxyethylene-oxypropylene-oxyethylene)

(PEO-PPO-PEO; Pluronics or Poloxamers)

are widely available, inexpensive and are used

in many detergent, cosmetic, pharmaceutical,

and biomedical applications. While the systems

may be well suited for the fabrication of

nanostructured materials, their melts are highly disordered

and do not form periodic morphologies due to their low

segregation strength.

The strength of phase segregation is determined by the

product of the Flory-Huggins interaction parameter (χ)

between the two constituents and the total molecular weight

or chain length (N) of the block copolymer. Therefore,

microphase segregated block copolymers typically have

either large χ, which is a measure of repulsion between the

segments, or a large molar mass. Commercially available

Pluronic copolymers have a low molecular weight and a

low interaction parameter, the product of which dictates

them to be phase-mixed and highly disordered. Here, we

show from small-angle neutron scattering measurements

that the disordered Pluronic copolymer melts form ordered

morphologies when blended with a widely available

homopolymer such as poly (acrylic acid) (PAA) or poly

(4-vinyl phenol). In other words, Pluronic copolymer melts

undergo a disorder-to-order transition with the addition

of a homopolymer that can selectively associate with the

polyoxyethylene segments through hydrogen bonding.

The results suggest a low cost, high volume approach to

the generation of ordered polymeric liquids for commercial

use [2]. The measurements were performed using the SANS

diffractometers at NG-3 and NG-7 at the NCNR.

We first focus on Pluronic copolymers blended with PAA.

Although PAA is known to associate with homopolymer PEO

through hydrogen bonding, its selectivity between PEO and

PPO is unknown. Differential scanning calorimetry and

infrared spectroscopy measurements on mixtures of low

molar mass homopolymers have shown that PAA interacts

with the ether oxygen in both PEO and PPO. Therefore, we

determined the selective miscibility of PAA from neutron

scattering measurements by employing a deuterium labeled

Pluronic-like copolymer (dF68; PEO-d6PPO-PEO). Figure 2

shows the change in absolute neutron scattering intensity,

full-width at half-maximum, and the position of the primary

neutron scattering peak from deuterated Pluronic-like

copolymer blended with hydrogenous PAA, collected as

a function of homopolymer concentration at 80 oC. The

neat copolymer comprises PEO at 80 % mass fraction

which pertains to body-centered cubic morphology when

microphase segregated. Above the melting point of PEO,

34

FIGURE 1: Schematic representing the generation of ordered microphases with the addition 

of a homopolymer to phase-mixed triblock copolymer melts. The phase-mixed copolymer is 

represented by the mixture of colors, blue and green, and the chemically homopolymer is represented 

by the color red. The phase-separated structures in the blend are thus represented by blue and yellow 

(i.e., mixture of red and green). In the figure m and n represent the number of EO and PO blocks, 

respectively.
NCNR 2007 ACCOMPLISHMENTS AND OPPORTUNITIES

References

[1] F. S. Bates and G. H. Fredrickson, Physics Today, 52, 32 (1999).

[2] V. R. Tirumala, A. H. Romang, S. Agarwal, E. K. Lin, and

J. J. Watkins, Adv. Mater., submitted.

[3] V. R. Tirumala, R. A. Pai, S. Agarwal, J. J. Testa, G. Bhatnagar, A.

H. Romang, C. Chandler, B. P. Gorman, R. L. Jones, E. K. Lin, and J.

J. Watkins, Chem. Mater., in press.

FIGURE 2: Change in (a) absolute intensity, (b) full-width at half-maximum, and (c) interdomain spacing calculated from the primary neutron 

scattering peak in deuterated Pluronic-like copolymer (dF68) thin film as 

a function of PAA concentration, φAA, at 80 oC. Concentration fluctuations 

in the disordered dF68 melt at 80 oC become strongly correlated with 

the addition of PAA between 10 % and 20 % mass fractions. The dF68 

copolymer corresponds to the case, m > n, described in Fig. 1.

however, the broad scattering peak from the neat dF68

copolymer represents weakly correlated concentration

fluctuations from a disordered liquid. The correlation

between deuterated PPO domains improves significantly

with the addition of PAA resulting finally in a relatively sharp

peak at 40 % homopolymer mass fraction. The increase in

scattering intensity from PAA/dF68 blends also suggests that

the homopolymer is selectively miscible with PEO segments.

The selective PAA/PEO- association may increase the effective

PEO-PPO segregation strength in Pluronic copolymers. An

increase in segregation strength should directly correspond

to an increase in the order-disorder transition temperature.

Figure 3 shows the change in SANS spectra from PAA/dF68

blends at 0 % and 40 % homopolymer mass fractions,

measured over the temperature range 80 oC to 175 oC. While

the neat copolymer clearly gets more disordered with an

increase in temperature, its blend with PAA remains highly

ordered without a change in morphology until 175 oC.

The effective χN in PAA/dF68 copolymer blends is much

higher than that in the neat copolymer due probably to the

selective hydrogen bonding between PAA and EO segments.

The selective AA/EO hydrogen bonding could increase

the repulsion between EO-PO thus improving the effective

segregation strength of the copolymer. This approach can

be further generalized to any homopolymer with strong

intermolecular association such as poly (4-vinylphenol),

poly (styrenesulfonic acid), etc. The difference in selectivity

affinity (for EO) and the strength of hydrogen bonding of

the homopolymer can be used as additional variables to

tune the melt phase morphology of Pluronic and Pluroniclike unsegregated and weakly segregated amphiphilic

block copolymers. When applied to commercially available

amphiphilic surfactants of low molecular weight and

low segregation strength such as Pluronic copolymers,

this simple and inexpensive approach can generate

well-ordered polymeric liquids of cubic, cylindrical, and

lamellar morphologies in commercially relevant quantities.

Such systems find many applications in the industrial

fabrication of nanostructured inorganic materials with

improved functionalities. For example, mesoporous silica

films synthesized from PAA/Pluronic F127 blends exhibit

exceptional order compared to those prepared from the

neat Pluronic F127 template [3].

FIGURE 3: SANS profiles from (a) neat dF68 copolymer and (b) its PAA 

blend thin film at 40 % mass fraction as a function of temperature. 

The neat copolymer is highly disordered in the range 25 oC to 150 oC, 

whereas the temperature stability peak near q = 0.6 nm-1 shows that 

the blend remains highly ordered even up to 175 oC. Data in (a) are in 

absolute units at 25 oC but are offset in intensity by factors (100, 200, and 

300) cm-1 at higher temperatures.

35
A Class of Micellar Solutions with

Viscosity Tunable by Light

Aimee M. Ketner and Srinivasa R. Raghavan1

1University of Maryland, College Park, MD 20742

Soft Matter/Polymers

FIGURE 1: UV-induced changes in CTAB/OMCA fluids at the molecular, 

microstructural and macroscopic levels.

I

magine a fluid that can be switched from a thick gel to a

flowing liquid upon application of an external field. Such

tunable fluids do exist: indeed, switching viscosity by application of an electric or a magnetic field has been known

for more than 50 years [1]. A third class of switchable fluids

using light as the external field has also been envisioned

[1-4]; however, such light-tunable or “photorheological”

(PR) fluids have remained of academic interest only—the

limiting factor has been the need for complex photosensitive molecules that require tedious synthesis [3,4]. Here, we

highlight our recent work [1] on developing a simple class

of PR fluids based on inexpensive chemicals that are readily

available from commercial manufacturers. These PR fluids

can thus be easily replicated in any industrial or academic

laboratory, and we hope this will spur on eventual applications for such fluids, possibly to construct microvalves,

dampers or sensors.

The scientific basis behind our PR fluids is depicted in Fig. 1,

with the essential principle being the propensity of amphiphilic molecules (containing both hydrophilic and hydrophobic

ends) to self-assemble in water to form nanoscale

assemblies. Importantly, the size and shape of these assemblies depends on the geometry of the amphiphiles. The

assemblies that we are primarily concerned with are called

“wormlike micelles”: these are long, flexible cylindrical chains

with diameters around 5 nm and lengths that can extend

up to a few microns. It is known that wormlike micelles can

be formed in water by combining the well-known cationic

surfactant, cetyl trimethyl-ammonium bromide (CTAB) with a

range of organic additives. To make our system lightsensitive, we use a cinnamic acid derivative as our additive.

This molecule, ortho-methoxy cinnamic acid (OMCA), is typically found with its C-C double bond in a trans configuration,

as shown in the top portion of Fig. 1.

However, when OMCA is irradiated with UV light, the

molecule photoisomerizes from trans to a cis configuration:

as shown in Fig. 1, the cis isomer has a bend or kink at the

double bond, giving the molecule a different geometry. The

effect of this photoisomerization on the sample viscosity is

illustrated visually in the bottom panel. Note that the original

CTAB + trans-OMCA sample is highly viscous and almost gellike in its appearance and it does not pour out of the tilted

vial. On the other hand, upon UV irradiation, the sample

(which is now composed of CTAB + cis-OMCA) has a low

viscosity, akin to water, allowing the sample to be poured easily out of its vial. This visual difference in flow properties can

be quantified by rheological measurements: it corresponds to

a decrease in the zero-shear viscosity (η0) of the sample by a

factor of about 10 000 [1].

Why does the photoisomerization of OMCA induce such a

dramatic drop in viscosity? The likely mechanism for this

effect is shown in Fig. 1, and it has two distinct aspects:

one at the molecular, and the other at the microstructural

level [1]. At the molecular level, we believe that the

geometry of trans-OMCA allows the molecule to adsorb

onto the cationic micelles. Such adsorption occurs

due to a combination of hydrophobic and electrostatic

interactions, with the aromatic ring partially submerged

into the hydrophobic core of the micelle. As a result of this

adsorption, the trans-OMCA counterions reduce the effective

charge on the cationic headgroups of CTAB and the lower

headgroup charge, in turn, allows the self-assembly of very

36
NCNR 2007 ACCOMPLISHMENTS AND OPPORTUNITIES

References

[1] A. M. Ketner, R. Kumar, T. S. Davies, P. W. Elder,

S. R. Raghavan, J. Am.  Chem. Soc. 129, 1553 (2007)

[2] T. Wolff, G. von Bunau et al., J. Phys.  Chem. 93, 4894 (1989)

[3] H. Sakai et al., J. Am.  Chem. Soc. 127, 13454 (2005)

[4] G. Pouliquen, C. Tribet, Macromolecules 39, 373 (2006).

FIGURE 2: SANS spectra for two CTAB/OMCA samples before and after 

UV irradiation. 

long wormlike micelles that entangle to produce a viscous

fluid. However, when OMCA is isomerized, the cis-OMCA

isomer has a much weaker tendency to adsorb onto the

micelles because its hydrophobic and hydrophilic regions

are not well separated. Thus cis-OMCA will tend to desorb

from the micelles, increasing the effective charge on the

surfactant headgroups. The increase in charge translates

into an increase in headgroup area, and the resulting

change in amphiphile geometry is reflected as a transition

to much shorter micelles (short cylinders or ellipsoids or

spheres). The shorter structures, in turn, impart a much

lower viscosity to the sample.

The microstructural basis for our PR fluids is thus a lightinduced transformation of long, wormlike micelles to much

shorter micelles (Fig. 1). To verify such a change, we turned

to small-angle neutron scattering (SANS) [1]. Samples for

SANS were made in D2O and measurements were conducted

on the NG-7 beamline at the NCNR. SANS spectra for intensity I vs wave-vector q are shown in Fig. 2 for two samples with

CTAB/OMCA concentrations of 20/20, and 5/5 mmol/L,

respectively. (We studied samples at low concentrations to

minimize intermicellar interactions). For both samples, UV

irradiation causes a significant drop in the intensity at low

q, which is a direct, qualitative indication of a decrease in

micelle size. To be more quantitative, we modeled the SANS

data from the 5/5 sample. Here, the intensity asymptotes

at low q to a slope of about –1 prior to irradiation, which

is indicative of long, cylindrical structures. We therefore

modeled the micelles as rigid cylinders, and the fit yielded a

micellar radius of 22 Å and a length of ca. 3000 Å. The same

sample after irradiation shows a plateau in SANS intensity

at low q, which suggests the presence of smaller and more

globular structures. Accordingly, we modeled the micelles

in this case as ellipsoids of revolution, and the best fit was

obtained for prolate ellipsoids with radii of 22 Å and 40 Å,

respectively, for their major and minor axes. Thus, SANS

confirmed that there is indeed a dramatic reduction in the

largest dimension of the micelles (a factor of about 100) due

to UV irradiation.

Finally, it is worth clarifying several aspects and limitations

of the PR fluids highlighted here. As indicated by the arrow

in Fig. 1, the light-induced transition in the CTAB/OMCA

system is a one-way effect, i.e., it is not reversible. The reason

for the irreversibility lies in the nature of the absorption

spectra of the trans and cis isomers of OMCA. Nevertheless,

we emphasize that the concept illustrated by Fig. 1 is general and should apply to other organic derivatives where

photoisomerizations are actually reversible. Indeed, work is

ongoing in our own laboratory to find such derivatives.

A second issue that arises with any type of PR fluid is one of

timescale. In our experiments, we used a 200 W mercury arc

lamp and our sample size was 5 mL. Under these conditions,

samples typically required about 30 min of irradiation to

achieve their full reduction in viscosity. The limitation is one

of path length and sample volume, i.e., faster effects can be

obtained with smaller samples.

In conclusion, we have demonstrated a UV-induced drop in

viscosity by more than four orders of magnitude in

CTAB/OMCA mixtures. Although this effect is not reversible, the notable point is that it has been achieved in a

simple system that can be replicated in any laboratory by

mixing two common chemicals. The microstructural basis

for this effect, which has been verified by SANS, is that UV

light induces a transition from long, wormlike micelles to

much shorter micelles. In turn, the microstructural changes

are predicated upon a trans to cis photoisomerization at the

molecular level.

37
Glass Transition Behavior of Thin Film

Miscible Binary Polymer-Polymer Blends

P. F. Green1; B. M. Besancon B. M. Besancon2; C. L. Soles C. L. Soles3

1University of Michigan at Ann Arbor, Ann Arbor, MI Ann Arbor, MI 2University of Texas at Austin, Austin, Texas 78712

3Polymers Division, National Institute of Standards and Technology, Gaithersburg, MD 20889

Soft Matter/Polymers

FIGURE 1: The neutron elastic scattering intensity vs temperature for the 

50 % mass fraction TMPC/dPS samples is dominated by the (hydrogenbearing) TMPC component. The TMPC effective glass transition temperature, identified with the crossing of the fitting lines, is Tg ≈ 445 K (172 °C).

Nanotechnology is the discovery and application ofnovel, inherently size-dependent properties of materials confined to the nanometer scale. It is generally difficult

to predict property deviations at this scale because they

manifest the influence of two factors: confinement and

interfacial interactions between the material (chemical)

constituents and the external interfaces [1]. The lengthscales over which the size-dependence is observed depend

not only on the class of material, e.g., atomic or long-chain

polymer, but also on the property observed.

One physical property of thin polymer films that is of

practical interest is the glass transition temperature, Tg,

below which a polymer becomes brittle. It is known that the

average Tg of homopolymer films thinner than h ≈ 40 nm

may increase or decrease with decreasing h. This

h-dependence appears to be associated with the relative

monomer-substrate, monomer-monomer and monomerfree surface interactions. Most applications of polymers,

however, involve mixtures of polymers. What, then, influences the Tg of a thin film homopolymer/homopolymer

mixture?

Spectroscopic ellipsometery (SE) measurements of the

average Tg of mixtures not only reveal thickness-dependent

changes in Tg with decreasing film thickness but further

indicate that the magnitudes of the changes are similar

to those in pure polymers. A combination of SE and

incoherent elastic neutron scattering (IENS) measurement

[2] reveal the influence of locally heterogeneous dynamics

on the average Tg of mixtures, leading to a completely new

mechanism by which the glass transition can be understood

in thin films.

We performed IENS studies on a completely miscible binary

polymer-polymer blend of deuterated polystyrene (dPS)

and tetramethyl bisphenol-A polycarbonate (TMPC), supported by SiOx/Si substrates (oxidized silicon wafers). The

thermodynamics of this system are well understood. The

properties of particular interest with regard to understanding the Tg of thin films are: (1) the Tg of PS is 100 °C lower

than that of TMPC; (2) the segmental dynamics of PS are

fast compared to TMPC at any given temperature; (3) PS

enriches the free surface (lower surface energy) whereas

TMPC preferentially enriches the oxide layer of the substrate; (4) Tg decreases with decreasing h in the PS/SiOx/Si

system, whereas the opposite is true in the TMPC/SiOx/Si

system. It could be argued, therefore, that since the dynamics

at the interfaces of these thin film samples are significantly

different, the Tg-h dependencies should differ significantly

from the pure homopolymer. However, SE measurements

show remarkably similar h-dependent behavior. At high

TMPC concentrations, greater than a mass fraction of 90 %,

Tg increases with decreasing film thickness, whereas for smaller

TMPC mass fractions Tg decreases with decreasing h [2].

Our INS measurements reveal evidence of a separate glass

transition of the TMPC component, distinct from the average

Tg of the film measured by spectroscopic ellipsometry. The

incoherent scattering intensity is heavily dominated by the

hydrogenous moieties in the TMPC whereas deuterium labeling

greatly reduces the incoherent scattering cross section of the

PS. The elastic scattered intensity, I(Q), is plotted in Fig. 1 as

a function of temperature for three samples containing 50

% mass fraction of TMPC. At temperatures T < 200 K, the

intensity of the elastic peak is well approximated by the

expression Ielastic(Q) ∝ exp(- Q2〈u2〉/3). In this expression, Q

is the scattering vector, and 〈u2〉 is the mean square atomic

displacement. The deviation from linearity of the data near

T ≈ 200 K for each curve in Fig. 1 is interpreted as a sub-Tg

38
NCNR 2007 ACCOMPLISHMENTS AND OPPORTUNITIES

References

[1] K. Binder et al., Prog. Polym. Sci. 28, 115 (2002); M. Alcoutlabi,

and G. B. McKenna, J. Phys. Condens. Matter 17, R461 (2005);

D. Long, and F. Lequeux, Eur. Phys. J. E 4, 371 (2001).

[2] B. M. Besancon, C. S. Soles, P. F. Green, Phys. Rev. Lett. 97,

057809 (2006).

[3] E. Kim et al., Macromolecules 28, 1979 (1995);

C. Wisniewsky et al., Eur. Polym. J. 20, 691 (1984).

[4] T. P. Lodge, and T. C. B. McLeish, Macromolecules 33,

5278 (2000).

FIGURE 2: TMPC effective component Tg values measured using INS 

(white symbols) vs TMPC concentration. For 30 nm films the average 

glass transition temperatures from ellipsometry (solid line and colored 

symbols) are plotted in (a) and for bulk samples by DSC (solid line and 

colored symbols) in (b). The fit from the Lodge-McLeish model is shown 

as red dashed lines in (a) and (b) whereas the solid lines guide the eye. 

relaxation, primarily reflecting methyl group rotations. The

glass transition temperature of the mixture, located where

the fit lines cross, as shown in Fig. 1, occurs at Tg ≈ 445 K

(172 °C) for both bulk and thin film samples. The values of

Tg determined using INS and ellipsometry (or differential

scanning calorimetry (DSC) for the bulk samples [3]) are

plotted as a function of composition for the 30 nm films

in Fig. 2a and for the bulk samples in Fig. 2b. The values

of Tg determined using these techniques are different: SE

and DSC measure essentially the same average values of

Tg, whereas the Tg of the TMPC component is found to be

systematically higher in the INS measurements.

The different Tg values measured by the INS and SE

techniques in these miscible blends might be rationalized

as follows. Studies of binary miscible polymer-polymer

blends that show a single average Tg can nonetheless show,

at a local level, evidence of the distinctly different Tgs and

relaxation times associated with each component in the

blend; i.e., locally the dynamics can still be heterogeneous.

The underlying reason for this dynamic heterogeneity

is discussed in terms of the chain connectivity, which

necessitates that a monomer on the A-chain (B-chain) will

have an intrinsically higher than average concentration of

A-monomers (B-monomers), locally as its nearest neighbors.

This is often referred to as a self-concentration, φs. The

effective local concentration, φeff, based on the LodgeMcLeish model [4], is determined by φs such that

φeff = φs + (1- φ s)φ , where φ is the bulk concentration. The

model assumes that the length scale of the local region

of enriched concentration around a given monomer is of

order nanometers and is independent of temperature. In

light of this, the component A of the mixture can sense a

different effective Tg determined by φeff, than the average.

It is probable that this notion is relevant here given that

the INS measurements are predominantly sensitive to the

methyl rotors on the TMPC, i.e., to the dynamics on the

time scale of a single monomer. This is in contrast to SE

(film) and DSC (bulk) measurements, which are sensitive

to the average Tg. The Tg concentration dependencies

of the different samples shown in Fig. 2 were fitted by a

virial equation from which the self concentrations φs were

determined [2]. The values of φs extracted from the fits to

data using all three techniques are comparable.

The implication here is that in thin films the selfconcentration concept appears to account for the

systematically higher values of Tg determined by INS

compared with those from SE. The fact that the TMPC

concentration is enriched at the wafer interface, which

would also lead to a local increase in the Tg near the

interface, does not seem to be dominant, since this kind of

interfacial segregation cannot occur in the bulk samples

where INS values are also found to be systematically higher.

Nevertheless, the Tg in these thin film polymer blends will

depend in a complicated manner on the relative monomersubstrate, monomer-monomer and monomer-free surface

interactions that determine the average Tg of homopolymer

films. The thickness-dependent average values of Tg 

polymer thin films reflect deeper underlying physics than

was originally thought to be important. We are continuing

these measurements using dielectric spectroscopy to

examine further details of the component dynamics.

39
Alzheimer’s Disease: Effects of β-Amyloid

Oligomers on Cell Membranes

F. Heinrich, M. Lösche1; G. Valincius, I. Ignatjev2; Y. Sokolov, J. E. Hall3

1NIST Center for Neutron Research, National Institute of Standards and 

Technology, Gaithersburg, MD 20899 and

Carnegie Mellon University, Pittsburgh, PA 15213

Biology

Alzheimer’s disease (AD) is a debilitatingneurodegeneration that affects millions of elderly

patients, particularly in the aging populations of developing

countries around the globe. The amyloid-β (Aβ) peptide, a

cleavage product of the membrane protein amyloid precursor 

protein (APP), has long been implicated in causing AD.

Enzymatic cleavage of APP liberates Aβ monomers into the

intercellular space of the central nervous system (CNS)

where the peptide may adopt a misfolded conformation

that is amenable to aggregation. Eventually, large insoluble

amyloid fibrils are formed which constitute the hallmark

feature found between destroyed nerve cells in affected

brains of diseased patients. Indirect evidence has recently

accrued that toxicity in the pathogenesis of AD may

primarily reside with a specific soluble oligomeric form

of Aβ rather than monomers or mature fibrils [1, 2].

These findings are starting to impact the search for

promising novel therapeutic approaches [3, 4]. It

is therefore timely to concentrate on molecular

biophysical studies of the properties of Aβ oligomer

particles [5]. We initiated such studies aiming to

reveal structure-function relations that govern

the association of prefibrillar Aβ oligomers with

membranes, thus beginning a new direction

in the century-old research on the origin of

Alzheimer’s disease.

Cell membranes are a complex blend of a large

number of distinct lipids that form a two-dimensional

matrix into which membrane proteins are

incorporated or with which they are peripherally

associated. One critically important function of

cell membranes in the CNS is to maintain a cation

gradient, and thereby a resting potential, between a

cell’s interior and external space.

The Hall lab at the University of California at

Irvine has monitored the conductivity of freestanding model membranes, so-called black lipid

membranes composed of just a single lipid or binary

lipid mixtures, in response to incubation with soluble

prefibrillar Aβ oligomers. They found a reduction

of the insulating properties of the membrane that

depends on its composition [6, 7]. In contrast to the

currently prevailing hypothesis which suggests that

Aβ oligomers form distinct membrane channels that

interfere with ionic dynamic balance, it was suggested

that the oligomers locally reduce the barrier to ion flow but

do not open water-filled channel structures. Subsequently, in

studies which invoked surface-stabilized, “sparsely tethered”

bilayer lipid membranes (stBLMs) [8], we determined the

structural impact of Aβ oligomers on membranes using

neutron reflectometry (NR) and correlated changes in

function, as observed with electrochemical impedance

spectroscopy (EIS), with these structural effects. This work

sets the scene for a broader research program on the

molecular-scale aspects of AD.

NR measurements were performed on NCNR’s AND/R

spectrometer [9]. stBLMs composed of fully hydrogenated

phospholipids showed reversible changes of the membrane

upon incubation with soluble Aβ oligomers. Results were

interpreted as a thinning of the hydrophobic bilayer core

2Institute of Biochemistry, Vilnius, LT-08662, Lithuania

3University of California at Irvine, Irvine, CA 92717

FIGURE 1: (a) NR and model reflectivities (lines) of an as-prepared stBLM and the same 

bilayer under the influence of Aβ oligomers. The lower inset shows residuals of the 

same data normalized to the NR of the neat bilayer, as well as the normalized residuals 

of a data set (not shown) of the bilayer after rinsing with protein-free buffer. The upper 

panel shows the nSLD models corresponding to the NR in the lower panel. (b) Changes 

of selected parameters that describe the stBLM models in (a). Upper panel: Development of the nSLD in the two distinct bilayer leaflets. Middle panel: development of the 

thickness of the two leaflets (assumed to be equal). Lower panel: Development of the 

neutron scattering length per unit area in the two distinct leaflets. The models rely on 

measurements of multiple solvent contrasts that are not all shown in panel (a). Similarly 

a number of results at various peptide concentrations are included in panel (b) for 

which the original data are omitted from panel (a) for clarity.

40
NCNR 2007 ACCOMPLISHMENTS AND OPPORTUNITIES

References

[1] R. Kayed, E. Head, J. L. Thompson, T. M. McI

S. C. Milton, C. W. Cotman, C. G. Glabe, Science 300, 486 (20

[2] D. M. Walsh, et al., Nature 416, 535 (2002).

[3] D. M. Walsh, et al., Biochem. Soc. Trans. 33, 1087 (2005).

[4] C. Glabe, Science 314, 602 (2006).

[5] D. Eliezer, J. Gen. Physiol. 128, 631 (2006).

[6] R. Kayed, Y. Sokolov, B. Edmonds, T. M. McI

S. C. Milton, J. E. Hall, C. G. Glabe, J. Biol. Chem. 279, 4

(2004).

[7] Y. Sokolov, J. A. Kozak, R. Kayed, A. Chanturija, C

J. E. Hall, J. Gen. Physiol. 126, 637 (2006).

[8] D. J. McGillivray, et al., Biointerphases 2, 21 (2007).

[9] J. A. Dura, et al., Rev. Sci. Instrum. 77, 074301 (2006).

[10] D. J. McGillivray, et al., Proc. Natl. Acad. Sci. USA

submitted (2007).

which depends in its extent on the nature of the lipid and

the peptide concentration. However, these NR results on

the interaction of (hydrogenated) Aβ oligomers with fully

hydrogenated stBLMs were limited in their predictive

power since it was impossible to locate the peptide particles

with respect to the membrane structure. NR experiments

that employed chain-perdeuterated DMPC—a saturated

phospholipid that is often used in model studies—were

much more revealing in that respect.

Figure 1a shows NR results in H2O-based buffer, as well

as the respective model fits, for an as-prepared stBLM

formed from chain-perdeuterated DMPC-d54, and

the same stBLM incubated with soluble Aβ oligomers

at a peptide concentration, cp = 12 μmol/L. Because

the inner hydrophobic sheath of the bilayer contains

a fully hydrogenated surface anchor [8] together

with the deuterated lipid, both leaflets show different

neutron scattering length densities (nSLD), ρn, and ar

distinguishable in the nSLD profile shown in the top

left panel in Fig. 1. These profiles indicate that oligomer

incubation increases the nSLD in the hydrophobic slab

and shifts the peak closer toward the substrate surface. As

shown in Fig. 1b, this experiment determines the structural

impact of the Aβ oligomers on the membrane: The peptide

interpenetrates the core of the membrane and affects both

leaflets of the stBLM equally, as observed in the changes

of the scattering length area density, Δρn×d, broken dow

into the values observed for the two bilayer leaflets (lower

panel in Fig. 1b). The bilayer thickness, d, decreases upon

increasing cp while Δρn×d goes through a maximum. Thi

suggests that peptide may incorporate massively into the

membrane, where it induces a compaction of the lipid

chains, followed by a lateral relaxation of the membrane

structure at high cp, presumably through the reorganization

of membrane material locally into the three-dimensional

defects. It is estimated that at cp > 10 μmol/L as much as

10 % volume fraction of the membrane may be composed of

the peptide.

Complementing EIS investigations (see the Bode plot,

inset in Fig. 2) confirm a dramatic decrease in membrane

resistance to ion conduction at low frequencies of the driving

voltage. While NR results which indicate that Aβ oligomers

penetrate the entire membrane might be consistent with the

assumption of channel formation, temperature-dependent

EIS shows that the activation energy, Ea, for ion transport

of across the membrane is much larger than expected for

water-filled channels (lower panel of Fig. 2). This provides

clear evidence that the Aβ-mediated conduction mechanism

is distinct from membrane poration.

While providing the closest view to date on the molecularscale aspects of the interaction of Aβ with membranes, these

results are still preliminary in character. A more rigorous

analysis and deeper understanding of the molecular-scale

aspects of membrane-toxicity of Aβ oligomers will require

more neutron scattering experiments with deuterated

peptide, which has not yet been available to us. Furthermore,

we aim at an in-depth comparison of the membrane effects

of other peptides (Aβ occurs in different lengths in vivo)

and different aggregation states (peptide monomers, larger

oligomeric association products, and fibrils). Deeper insight

into the molecular aspects is also expected from coupling

the results of scattering experiments with molecular

dynamic computer simulations. These efforts, required

to make serious progress toward an unraveling of the

century-old puzzles posed by Alzheimer’s disease, are

currently underway.

FIGURE 2: a) EIS Bode plots of a DOPC stBLM in 0.1 M NaCl, pH 7.3, as a 

function of Aβ concentra­tion. b) Arrhenius plots of the con­ductivit

of a membrane with Aβ (cp = 1.61 μmol/L) and of the elec­trolyt

measured in the same expe­riment. Electrolyte conductivity has bee

divided by 1000. Activation energies derived from the slopes are 

Ea = 36.7 kJ/mol and 6.5 kJ/mol.

41
Protein Structure and Hydration Probed by SANS

C. B. Stanley, S. Krueger1; V. A. Parsegian, D. C. Rau2

1NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899

2Laboratory of Physical and Structural Biology, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892

Biology

FIGURE 1: SANS of guanylate kinase (GK) conformations at 5 mg/mL in 

D2O (data points) and SANS profiles calculated from the corresponding 

crystal structures using Xtal2sas (solid lines). Curves are shifted for clarity. 

Inset: Corresponding GK structures from x-ray crystallography: 1, GK 

(1EX6); 2, GK/GMP (1EX7); and 3, GK/GMP/MgADP (1LVG). 

Proper protein function relies on interactions thatcreate correctly folded and assembled structures still

maintaining the flexibility required for specific activity.

Since these interactions are mediated by hydration, the

energetics of protein function are necessarily coupled to

water activity. Modulating biomolecular systems through

the addition of solutes that vary in chemistry and size can

provide a better understanding of the interactions including

the role of water. Nature utilizes a variety of small solutes,

called osmolytes, to protect proteins against thermal and

chemical denaturation. Often osmolytes act indirectly

through an exclusion from water hydrating biomolecular

surfaces or from water sequestered in cavities. For similar

reasons, stabilizing agents are added to protein solutions

used in biotechnology and pharmaceutical applications.

Here, we use small-angle neutron scattering (SANS) coupled

with osmotic stress to investigate the hydration of guanylate

kinase in the presence of solutes [1]. By taking advantage

of the neutron contrast variation that occurs upon solute

addition, the number of protein-associated (solute-excluded)

water molecules can be estimated. These results provide a

framework for studying similar biomolecular systems using

neutron scattering.

An instructive way to view solute effects on biological

systems is through the osmotic stress method [2]. This

approach considers the various interactions from an added

solute while also affording the measurement of forces

between biopolymers and hydration changes accompanying

biomolecular reactions. The solute size and chemical nature

determines its exclusion from biomolecular surfaces, thereby

acting osmotically on these regions and favoring more

dehydrated states. Importantly, since osmotic stress mimics

the influence of macromolecular crowding characteristic of

the cell, its perturbing effects can teach us about molecular

function in vivo.

Guanylate kinase (GK) is a 20.5 ku (20.5 kDa) protein that

performs phosphoryl transfer from adenosine triphosphate

(ATP) to guanosine monophosphate (GMP). We chose

to study this protein because its structure contains a deep

cavity for ligand binding, and it also undergoes largescale conformational changes upon binding ligands.

Conformational changes can be followed using SANS

(Fig. 1) where Guinier fits indicate the protein radius of

gyration, Rg, decreases from (17.2 ± 0.1) Å to (16.

Å upon binding GMP. The ATP-binding site also can be

closed by addition of magnesium adenosine triphosphate

(MgADP) resulting in Rg = (16.2 ± 0.1) Å. Calculated S

profiles (Fig. 1, solid lines) made from the corresponding

crystal structures using the Xtal2sas program [3] and

references therein, demonstrate good agreement with the

experimental data.

When solutes are introduced, any exclusion of solute away

from the protein results in a preferential hydration. In the

context of osmotic stress, these protein-associated water

molecules that are thermodynamically important based on

their exclusion from the bulk solute are what we term protein

hydration. By considering the protein and protein-associated

water as a composite particle, and accounting for the change

in bulk solution scattering length density with solute volume

fraction, Fig. 2 shows that solutes in the series: glycerol,

triethylene glycol (TEG), and poly(ethylene glycol) (PEG) of

molecular weight (MW) 400 and 1000 induce an additional

scattering contribution above what is obtained from protein

in H2O/D2O solvent alone. This excess contribution is

attributed to protein-associated water [4]. Protein hydration

can be expressed in terms of the number of water molecules

associated with the protein, Nw (values given in Fig. 2).

Glycerol is the least excluded solute, likely due to both its size

42

Rg = 17.2 ± 0.1 Å

Rg = 16.4 ± 0.1 Å

Rg = 16.2 ± 0.1 Å
NCNR 2007 ACCOMPLISHMENTS AND OPPORTUNITIES

References

[1] C. B. Stanley, S. Krueger, V. A. Parsegian, and D. C. Rau, 

Biophys. J. (submitted).

[2] V. A. Parsegian, R. P. Rand, and D. C. Rau, Proc. Natl. Acad. Sci. 

USA 97, 3987 (2000).

[3] S. Krueger, I. Gorshkova, J. Brown, J. Hoskins, K. H. McKenney, 

and F. P. Schwarz, J. Biol. Chem. 273, 20001 (1998).

[4] H. B. Stuhrmann, J. Haas, K. Ibel, M. H. Koch, and 

R. R. Crichton, J. Mol. Biol. 100, 399 (1976).

FIGURE 2: GK contrast variation by H

2O/D2O (black line) and solute/D2O. 

Plotted is the square root of the zero-angle neutron scattering intensity, [I(0)NA/cM]1⁄2, vs bulk solution scattering length density, ρ0, where the 

observed excess contribution to the H

2O/D2O contrast variation from 

added solute is related to the hydration of the protein, N

w, in the pres

-

ence of that particular solute. Inset: Models of GK (cyan) with proteinassociated water molecules (red) that closely correspond to Nw for the 

solutes TEG and PEG 400. Note that TEG is equivalent to PEG of MW 150. 

and chemical nature. GK hydration then almost triples when 

going from TEG to PEG 400.

The corresponding changes in GK Rg are given in Fig. 3. 

No change in protein Rg is observed with added glycerol, 

consistent with the negligible Nw

The solute size dependence observed with Nw in Fig. 2 

is qualitatively mirrored in the effects on Rg. Isothermal 

titration calorimetry measurements of hydration changes 

accompanying ligand binding to GK display the same 

trend with solute size for these solutes and also indicate no 

protein conformational change occurs from solute alone 

over the range of solutes and concentrations applied in the 

SANS experiments. Based on the size-dependence of solute 

exclusion, the volume of protein-associated water, and similar 

SANS measurements we have made with lysozyme, it is 

determined that the majority of water associated with GK for 

these solutes likely resides in the cavity (see models in Fig. 2, 

inset). These results illustrate the potential use of SANS and 

osmotic stress for resolving structural details based on solute 

exclusion.

We have demonstrated methods of using SANS combined 

with osmotic stress to determine protein hydration in the 

presence of a series of solutes. The roles of solute size and 

chemistry, along with protein structure, in determining 

the extent of solute exclusion, and consequent protein 

hydration, have been investigated. Another opportunity for 

this research is to use deuterated solutes to unambiguously 

measure protein structure with solute addition. This can 

provide assurance that there are no structural changes for 

an added solute or be purposely used at high concentration 

to induce structural changes and measure the osmotic work. 

We hope this study forms the basis for such promising future 

research so that structural information about biological 

systems can be directly connected with their corresponding 

thermodynamics. SANS experiments were performed on the 

NG3 and NG7 30 m SANS instruments at the NIST Center 

for Neutron Research.

FIGURE 3: Measured change in GK R

g vs solute volume fraction, 

fv,solute, 

determined by SANS. Dashed lines are given for glycerol and PEG 1000 

to guide the eye. 

43

glycerol

TEG

PEG 400

PEG 1000

 determined from I(0). 
Melting in Dehydrated Lipid Bilayers

M. Doxastakis1, S. Ohtake1; V. García Sakai2; J. K. Maranas3; J. J. de Pablo4

1The University of Wisconsin, Madison, WI 53706

2National Institute of Standards and Technology

NIST Center for Neutron Research, Gaithersburg, MD 20899 and 

Biology

FIGURE 1: The local cage size in tail labeled (dhDPPC, red circles) and 

head labeled (hdDPPC, blue diamonds) samples referenced to 70 K, the 

lowest measured temperature. The inset image presents simulation 

coordinates of a single lipid molecule at 310 K, plotted every 

400 ps over a time period of 4 ns.

Lipid bilayers are ordered structures that assemblein water as a result of the connection of hydrophilic

head groups to hydrophobic tail regions. They form the

biological membrane enclosing cells, as well as simplified

enclosures, termed liposomes, used for drug delivery, gene

therapy and immunization. Bilayers in biological functions

and other applications are normally hydrated, and as a

result the properties of hydrated bilayers are well studied

and understood. This includes one of the most important

physical properties of membranes: the melting transition

that differentiates a solid-like state (gel phase) from the

liquid state (liquid crystalline phase) [1]. The importance

of this transition derives from the fact that cells and other

enclosures leak their contents as it is crossed, which causes

cell death or failure of liposomes as carriers. Althou

they have received less attention, dehydrated lipid bilayers

are important both biologically, where certain organisms

modify their cell membranes to survive desiccation [2],

and in application as liposomes, where preparation of

liposomal carriers requires drying and rehydration. In the

former case, protection against dehydration is linked to

changes in melting transition temperatures of hydrated

and dehydrated membranes when additives are present.

The work described in this highlight targets the melting

transition in dehydrated lipid bilayers, filling the gap in

our understanding of these systems.

Our approach uses a combination of quasi-elastic neutron

scattering (QENS) experiments and molecular simulations

to characterize mobility above and below the transition. We

perform investigations on freeze-dried model liposomes,

comprised of a single type of lipid molecule: dipalmitoylphosphatidylcholine (DPPC). These liposomes are a

realistic representative of those used in applications, and

they approximate biological cell membranes. We exploit

the ability of neutrons to preferentially probe the motion

of specific protons in the sample: by considering DPPC

with deuterated head-groups (dhDPPC), we probe tail

mobility; and by deuterating the tails (hdDPPC), we probe

head-group mobility. In all of these dehydrated samples,

the melting transition occurs near 370 K. As with any

melting transition, the gel to liquid crystalline transition

in a lipid bilayer involves a rapid rise in molecular mobility

with temperature, easily observed using calorimetry. The

analog to calorimetry in QENS is the fixed window scan, in

which the elastic intensity, representing motion slower than

the instrumental resolution, is monitored as a function of

temperature. Fixed window scans on dhDPPC show that

when dehydration is achieved via freeze-drying, the melting

feature arises from the lipid tails. By comparison, scans on

hdDPPC show a more gradual change [3].

We may regard mobility as rattling within a local cage

superimposed with translation of the cage center of mass.

Below the melting temperature, translation is minimal

and it is possible to derive the local cage size from fixed

window scans. The behavior of the local cage size with

temperature is illustrated in Fig. 1. Below 220 K, only

vibration occurs, as evidenced by the linear relation of

mean squared displacement and temperature. Differences

between head and tail proton motions are also small. Above

this temperature, localized motion distinct from vibration

appears with obvious differences in head and tail mobility.

Above the highest temperature on the plot, 340 K, motion

is no longer localized and thus its spatial extent may not

be extracted. The appearance of non-localized motion,

particularly in the lipid tails, is a hallmark of the liquid

crystalline state. The mean squared displacements in Fig.

are averages over all tail or head group protons. Because

these regions of the lipid molecules are connected, the

difference in local cage sizes implies that cage size varies with

the location of tail protons: those immediately near the head

group region must explore smaller cage regions than those at

the tail ends. This suggestion is validated with the simulation

image provided in the figure inset. The image represents

The University of Maryland, College Park, MD 20742

3The Pennsylvania State University, University Park, PA 16802

4The University of Wisconsin, Madison, WI 53706

44
NCNR 2007 ACCOMPLISHMENTS AND OPPORTUNITIES

References

[1] J. F. Nagle, Ann. Rev. Phys. Chem. 31, 157 (1980).

[2] J. H. Crowe, L. M. Crowe, Nature Biotechnol. 18, 145 (2000).

[3] M. Doxastakis, S. Ohtake, V. García Sakai, J. K. Maranas,

J. J. de Pablo, Biophys. J. 92 (1), 147(2007).

[4] L. Carpentier, M. Beé, A. M. Giroud-Godquin, P. Maldivi,

J. C. Marchon, Mol. Phys. 68, 1367 (1989).

a time progression of a single lipid molecule over an

interval approximately equivalent to the instrumental

resolution, and demonstrates a variation in spatial

exploration with tail position.

The localized motion characterized in Fig. 1 describes

states below the melting transition. Since the rapid

change in mobility at this transition appears in the tail

protons, we focus on the dhDPPC sample, and investigate

the associated change in dynamics. This

requires characterization of neutron energy

changes during scattering, rather than

merely the elastic fraction. Because these

measurements are more time consuming, only

two temperatures, bracketing the transition,

are presented in Fig. 2. These spectra consist

of two parts which roughly correspond to

localized motion observed for times less than

50 ps, and larger scale motion for times greater

than 200 ps. Localized motion, the spatial

extent of which was characterized above, exists

both above and below the melting transition.

Larger scale motion only occurs above the

melting transition, as indicated by the absence

of decay from 200 ps to 4 ns at 330 K. Although

the experimental data do not decay enough to

clearly identify the nature of this motion, the

simulation snapshots suggest that larger scale

motion of lipid tails originates from the onset

of conformational changes in the head-group

regions, and may be rotational in nature.

We focus on localized motion occurring both above and

below the melting transition described by data at times

less than 50 ps to extract information about the nature

and timescale of the motion. Based on analysis of the

fixed window scans and simulation snapshots, we expect

that motion occurs by exploration of local regions, the

size of which varies with location along the lipid tail. Our

fitting procedure yields the elastic incoherent structure

factor (EISF) of the localized process as a fit parameter,

and examination of this variable in comparison to model

functions can both confirm localized motion and provide

information on its geometry. We choose a model describing

motion as diffusion within impenetrable spheres [4]. As

confirmed by the comparison in Fig. 2, a single sphere size is

insufficient to describe the experimental data. If the sphere

radius is allowed to vary with tail position, the same model

provides an excellent description of the data. Rather than

impose a linear variation of sphere size with tail position,

we obtain the variation from our molecular dynamics

simulations, where mobility at individual locations may be

easily isolated.

Our investigation identifies several important characteristics

on a molecular level. Below the melting transition,

significant localized mobility is present in the lipid

tails, with the spatial extent of this motion growing with

temperature well before the transition occurs. The size of

the region within which localized motion takes place is not

homogeneous, but rather varies with location along the lipid

tail. The rapid gain in mobility over the transition from the

gel to liquid crystalline phase is observed in the lipid tails,

and involves the onset of non-localized motion. This tail

motion appears to be enabled by conformational transitions

of the head groups at higher temperatures. This molecul

picture of melting in dehydrated lipid bilayers provides a

baseline against which the behavior of additive modified

systems may be compared to determine the mechanism

FIGURE 2: Mobility of dhDPPC above (395 K, red symbols) and below 

(330 K, black symbols) the melting transition. Dynamic data from two 

instruments (plotted here as the intermediate scattering function) are 

combined to form a single curve. Squares correspond to motion over 

a spherical region with diameter of 4 Å, and circles to motion over 

7.5 Å. The inset images present simulation coordinates of a single lipid 

molecule plotted every 400 ps over a time period of 4 ns. 

FIGURE 3: Comparison of the EISF extracted from fits to the short-time decay and a 

model of diffusion within impenetrable spheres. Two versions of model predictions are 

provided at 310 K. The dashed line uses spheres with a radius independent of tail position, as illustrated in the left lipid tail in the image. The solid line allows the sphere radius 

to vary with position, as illustrated in the right lipid tail in the image. The radius variation 

taken from molecular dynamics simulation is provided in the figure inset. 

45
Revealing Light-Enhanced Protein Activity

with Neutrons

C. T. Lee, Jr., A. C. Hamill, S. C. Wang1; A. Faraone2

1University of Southern California, Los Angeles, CA 90089

2NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899

Biology

FIGURE 1: SANS data of lysozyme-azoTAB solutions as a function of photosurfactant concentration, along with in vitro lysozyme conformations 

determined from shape-reconstruction analysis of the SANS data. The 

crystal structure of lysozyme (PDB code 6LYZ) is shown for comparison. 

Of all the molecules found in living organisms, proteinsare the most important. Enzymes act as catalysts;

rhodopsin aids vision and G-protein-coupled-receptors

mediate smell and taste. To a large extent, protein function

is determined by protein conformation, particularly in

the case of enzymes where folding results in an active site

that allows for selective binding of substrates. However,

the static “lock and key” mechanism has been replaced

in modern enzymology with the form-dynamics-function

relationship and the view that enzyme dynamics can have

an equally important role in catalysis. To directly examine

this relationship, the interaction of a photoresponsive

surfactant with lysozyme has been investigated as a means

to control the enzyme structure, flexibility, and activity with

light illumination. Conformational changes as a function

of photoresponsive surfactant concentration and light

illumination were measured through shape-reconstruction

analysis of small-angle neutron scattering (SANS) data.

The SANS-based in vitro structures indicate that lysozyme

adopts a partially-unfolded conformation in the presence

of the photosurfactant under visible illumination, while UV

illumination causes the protein to refold to a near-native

structure. Protein swelling occurs principally away from

the active site near the hinge region connecting the α and

β domains, leading to enhanced domain motions that we

directly measured with neutron spin echo (NSE). Th

enhanced enzyme flexibility is accompanied by an 8-fold

increase in enzymatic activity relative to the native state,

leading to complete photoreversible control of the structure,

dynamics, and function of lysozyme.

Azobenzene-based photoresponsive surfactants (“azoTAB”,

see Fig. 1) have recently been utilized to induce reversible

changes in protein conformation with light illumination,

with relatively high resolution in vitro protein structures

determined with small-angle neutron scattering (SANS)

[1-4]. A photoisomerization between the visible-light

trans (relatively hydrophobic) and UV-light cis (relatively

hydrophilic) forms of the azobenzene moiety allows

photocontrol of surfactant interactions with various proteins.

With bovine serum albumin, the initial unfolding was

localized to the hydrophobic α-helical segments in the

C-terminal portion of the protein [1, 3]. In contrast, for

α-chymotrypsin consisting primarily of β structures, only

small changes in the overall size of the protein were

observed (≈ 7 % increase in the radius of gyration), however,

this subtle structural rearrangement was sufficient to convert

intramolecular β structures into intermolecular β sheets and

lead to eventual amyloid fibril formation [4].

For lysozyme containing both α and β domains, the SANS

data in Fig. 1 indicate that the photosurfactant swells

lysozyme under visible light (photosurfactant switched

“on”), while the protein refolds to a native-like conformation

under UV illumination (photosurfactant switched “off”). As

previously described [2], shape reconstruction of the SANS

data involves approximating the protein as a collection of

scattering centers whose positions are adjusted to fit the

experimental scattering curve. The resulting conformations

of lysozyme are shown in Fig. 1 along with the x-ray

crystallographic structure (PDB code 6LYZ). While at low

azoTAB concentrations the SANS-based structures are similar

to the crystal structure of pure lysozyme, the true utility of

SANS is seen at elevated azoTAB concentrations where the

degree and location, of protein swelling can be determined.

Lysozyme is observed to swell primarily in the lower portion

of the molecule away from the active site in the so-called

hinge region, which gives rise to a progressively more open

active-site cleft.

From these SANS-based in vitro conformations, lysozyme

activity against glycolchitin was determined as a function of

46
NCNR 2007 ACCOMPLISHMENTS AND OPPORTUNITIES

References

[1] C. T. Lee, Jr., K. A. Smith, T. A. Hatton, Biochemistry 44 (2),

524 (2005).

[2] A. C. Hamill, S-C. Wang, C. T. Lee, Jr., Biochemistry 44 (46),

15139 (2005).

[3] S-C. Wang, C. T. Lee, Jr., J. Phys. Chem. B 110 (32), 16117

(2006).

[4] A. C. Hamill, C. T. Lee, Jr., Biochemistry 46 (26), 7694 (2007).

[5] Z. Bu, R. Biehl, M. Monkenbusch, D. Richter, D. J. E. Callaway,

PNAS (USA) 102 (49), 17646 (2005).

FIGURE 2: NSE measurements of the effective diffusion coefficient 

of 10 mg/mL lysozyme solutions in the presence of the azoTAB 

photosurfactant that is active under visible illumination and passive 

under UV illumination. Solid lines account for rigid-body motions (translation/rotation).

azoTAB concentration and light conditions, revealing an

8-fold increase in activity (i.e., “superactivity”) with lysozyme

in the swollen form. In order to form the enzyme-substrate

complex, it has been reported that the active-site cleft of

lysozyme has to first open (to allow the substrate to enter

the active site) and then close (to return the enzyme to a

state similar to the native conformation) through hingebending motions of the α and β domains. Thus, it may be

expected that domain motions play an important role in

the catalytic process.

The rates of enzymatic reactions are controlled by the

height of the activation energy barrier. Thus, to induce

superactivity requires that enzyme flexibility be increased in

such a way that transition-state structures are preferentially

sampled. With this in mind, the superactivity observed in

the presence of azoTAB under visible light could be a result

of the higher degree of swelling of the hinge region, which

would be expected to lead to enhanced hinge-bending

motions. At the ensemble level as in Fig. 1, this is manifested

by an overall broadening of the active-site cleft, analogous

to regions with high temperature factors (B factors) in x-ray

crystallographic structures that are often associated with

regions undergoing large thermal motions.

To directly measure protein domain motions, neutron

spin echo (NSE) experiments were performed at NIST

on lysozyme-photosurfactant systems. While SANS is

the neutron analogue of static light scattering with both

measuring scattering intensity, NSE is analogous to dynamic

light scattering, since both measure a diffusion coefficient.

In contrast to translational diffusion determined from

DLS, however, NSE can further access motions over time

scales from 0.01 ns to 100 ns and length scales from 10

Å to 150 Å. As seen in Fig. 2, NSE reveals a deviation in

the effective diffusion coefficient from that expected for

purely rigid-body motions (i.e., translation plus rotation

[5]) in the presence of surfactant activated under visible

light, while converting the surfactant to the passive

form with UV light results in a “dormant” protein in the

nanosecond/nanometer regime, similar to native lysozyme.

This deviation is observed as the length scale L (= 2π/Q)

decreases to values approaching the protein diameter. Thus,

NSE is detecting nanosecond domain motions within the

protein. Interestingly, these internal motions occur with

the aforementioned 8-fold enhanced “superactivity” of the

enzyme versus the native state. Thus, Fig. 2 provides a direct

measure of photo-induced protein internal motions leading

to enhancements in enzyme activity.

Through combined SANS and NSE measurements,

unique insight is obtained into the mechanisms by which

photoreversible control of protein structure/flexibility

lead to enhanced enzyme activity. The in vitro enzyme

conformations from SANS reveal that lysozyme swells

primarily in the hinge region connecting the α and β

domains. This in turn leads to nanosecond/nanometer

domain motions within the protein, directly measured

with NSE experiments, as well as to an 8-fold increases in

enzymatic activity relative to the native state. By examining

the complete form-dynamics-function triad of lysozyme, these

results suggest a general procedure by which enzymatic

activity could be increased through enhancements in

enzyme flexibility.

A

This material is based upon work supported by the National

Science Foundation under Grant No. 0554115.

47
NCNR Images 2007

UConn’s Sam Emery confers with mentor Barry Wells 

at SPINS, working with NCNR’s Hye-Jung Kang.

UMBC’s Robert Reno and his students tour the NCNR.

NCNR’s Paul Butler is amused as Charlie Glinka 

dubiously scans a “gift” at Charlie’s retirement party.

Jim Rhyne (LANL), 

formerly of the 

NCNR, back for 

a visit to use the 

NG-3 SANS.

Kaikun Yang (Binghamton U) views USANS results 

with NCNR’s David Mildner.

NCNR 2007 Summer School students Rafael Jaramillo and Kenneth Desmond present the results 

of their Spin Echo...

NCNR’s Juscelino 

Leão, Ben Ueland, 

Sarah Poulton and 

Ying Chen taking 

caution in setting 

up the BT-9 tripleaxis spectrometer.

48
NCNR 2007 ACCOMPLISHMENTS AND OPPORTUNITIES

Mark Dadmun (center) and his UT volunteers with 

NCNR’s Sushil Satija (left) at the NG-7 reflectometer.

Spectrometer experiment as presider 

Antonio Faraone and other participants 

look on attentively.

Monica Branco (U Del) at the controls during a Spin-Echo 

Spectrometer Run.

NCNR’s Bob Williams describes the cold source to RPI’s 

Li Liu (left) and her students.

NCNR’s Mike Gue (left) and George Baltic (right) 

move a slice of shielding at BT-7 with Doug 

Ogg’s help.

Danmin Liu and 

Qing Huang 

turn for the 

camera at the 

BT-1 diffractometer.

Danilo Pozzo (U 

of Washington) 

gets a pointer 

from Lionel 

Procar at the 

NG-7 30 m 

SANS.

49
Extending Neutron Activation Analysis Capabilities

B. E. Tomlin, R. Zeisler, R. M. Lindstrom1

Advances in Measurement

[1] W. D. Ehmann and D. M. McKown, Anal. Lett. 2, 49 (1969).

References

Trace elements play an important role in everyday life.Many of the high-tech devices that modern society

relies upon require high-purity raw materials for their

manufacture, and the content of trace elements in these

materials can have a significant effect on their properties.

In biological systems, trace elements play two roles—as

essential nutrients for an organism’s survival and as toxic

substances that can cause disease and death at extremely low

concentrations. Given the critical role of trace element

the characterization of trace element compositions in a wide

variety of materials is crucial for advancements in science,

industry and medicine.

Neutron activation analysis (NAA) is a powerful method

for the determination of a wide variety of trace elements,

independent of the chemical environment of those

elements. NAA is based on the measurement of nucle

gamma radiations. The technique of gamma-gamma (γ

coincidence spectrometry is a means of counting γ rays with

a much higher level of discrimination by distinguishing

radioactive decay events with unique signatures from the

much larger number of all other decay events. Nucle

spectroscopists commonly employ γγ coincidence

techniques, but this technique is not widely used within

the nuclear analytical community. Early work on the u

of γγ coincidence measurements as a means of improving

the sensitivity of NAA for rare earth elements was reported

in the literature almost forty years ago [1]; however, little

development of the technique has occurred since then.

New trends in instrumentation, however, promise greater

improvements than have been achieved in the past.

In order to fully explore the use of γγ coincidence NAA

in characterizing standard reference materials (SRM), a

prototype γγ coincidence spectrometer, as shown in the

inset of Fig. 1b, has been constructed at the NIST Center

for Neutron Research using high-purity germanium γ-ray

detectors and state-of-the-art digital instrumentation. This

system will extend to quantitative analyses the general

approaches used by nuclear spectroscopists employing stateof-the-art signal processing procedures.

Gamma-ray spectra with significant reductions in

background components have been attained with the

coincidence spectrometer at NIST. Figure 1 illustrates t

effect of coincidence gating on a γ-ray spectrum. Figure 

shows a portion of an ungated, conventional singles γ-ray

spectrum for SRM 1598a Animal Serum, with the Cs-134

605-keV peak labeled. In contrast, Fig. 1b shows

a coincidence γ-ray spectrum, gated on the Cs-134

796-keV transition, over the same energy range as Fig. 1a.

The coincidence spectrum demonstrates both a reduction in

the overall spectral background, as well as, the elimination of

the overlapping Sb-124 γ-ray peak which causes the distorted

peak shape in Fig. 1a.

The application of γγ coincidence spectrometry to N

here at NIST will extend our capabilities for quantifying

trace elements in a broad array of reference materials and

other critical samples. The newly constructed prototy

γγ coincidence spectrometer has been found to provide

significant enhancements in γ-ray counting sensitivity

and selectivity. Based on these positive results, it is fully

expected that γγ coincidence NAA will make a considerable

contribution to the Analytical Chemistry Division’s SRM

program. Work is presently underway employing 

coincidence spectrometer to characterize a number of trace

elements in a new bovine liver SRM.

1Analytical Chemistry Division, National Institute of Standards and Technology, Gaithersburg, MD 20899

FIGURE 1: Inset: the NIST prototype γγ coincidence spectrometer. 

(a) A representative singles γ-ray spectrum. (b) A representative γ-ray 

gated coincidence spectrum.

50
Advances in Measurement

Reciprocal Space Neutron Imaging

D. A. Pushin and D. G. Cory1; M. Arif and D. L. Jacobson2; M. G. Huber3

Here we describe an interferometric method forcoherent, reciprocal space neutron imaging

which overcomes the spatial resolution limitations

of existing neutron imaging methods based on

position sensitive detectors. The method implements

a spatial encoding of the neutron phase similar to

that used in nuclear magnetic resonance imaging.

By moving neutron imaging from real to reciprocal

space we avoid the need for position sensitive detectors

and improve the potential image resolution. Neutron

imaging is complementary to other noninvasive imaging

methods, such as x-ray imaging and magnetic resonance

imaging. Neutrons are transparent to many high

Z-number materials and are scattered by many light

elements, primarily hydrogen. Examples of neutron

imaging include density fluctuations of hydrogen in metals,

density of polymeric overlayers, formation of water in

hydrogen fuel cells, crystallography for structural biology,

and magnetic domain distributions.

The essence of the reciprocal space measurement is to

create in one leg of the interferometer a spatial linear

phase grating with a controllable wave-number. Such a

grating in the neutron phase over the neutron beam can be

created by placing a prism in one leg of the interferometer

as shown in Fig. 1. If a sample is placed in the second

leg of the interferometer then the observed contrast will

be dependent on the Fourier coefficient of the spatial

distribution of the coherent cross-section of the sample at

the wave-number selected by the grating. Since the grating

wave-number is experimentally controllable we can map

out the full reciprocal space description of the sample.

This is easily and directly invertible to recover the image

of the sample [1]. The method does not require a 2-D

detector and thus has the potential to improve the spatial

resolution significantly compared to the current limit of

tens of micrometers. From the Nyquist theorem, the image

resolution depends on the maximum measured wave

number, |∆r| = π/|kmax|

To achieve 5 μm resolution we need to use a maxim

gradient of the order of 6.3 x 105 rad m−1 or a fused silica

wedge with an 81° wedge angle. In our case the maximum

gradient (2 x 104 rad m−1) was produced by two 6° wedges

corresponds to a resolution of 160 μ

Figure 2 shows an example 1-D image of a step-like

sample that reveals the resolving power of the method.

The sample partially covers the top of the beam. On the

left (a) we report the raw data and on the right (b) the

reconstructed and measured images. The smooth curve 

(a) is the best fit for the known step-like sample shape. T

excellent quality of the data mirrors the quality of the beam

characteristics (profile, momentum spread and divergence).

Extensions of the method to 2-D are easily accomplished by

rotating the sample or by rotating the grating [2].

1Massachusetts Institute of Technology, Cambridge, MA 02139

2NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899

3Department of Physics, Tulane University, New Orleans, LA 70118

FIGURE 2: Step-like sample data. The sample is a thin (25 μm) fused silica slab 

that covers only part of the neutron beam. On the left (a) we show raw data 

with the sample (open red circles) and without the sample (filled blue circles). 

Reconstructed images are shown on the right (b). Open blue circles represent 

reconstructed image of the step-like sample, the purple line is the1D image of 

the sample obtained with a position sensitive detector, and the green dashed 

line is the beam profile on the position sensitive detector without a sample.

[1] D. A. Pushin, M. Arif, D. L. Jacobson, C. K. Do, and D. Cory,

Physica B 385-386, 1402 (2006).

[2] D. A. Pushin, M. Arif, D. L. Jacobson, M. G. Huber, and

D. Cory, Appl. Phys. Lett. 90, 224104 (2007).

References

FIGURE 1: Schematic diagram of imaging experiment at NIST. 

A neutron beam, coming from the left, is coherently divided via Bragg 

diffraction in the first blade of the neutron interferometer into two 

beams. These beams travel along paths I and II. The phases which the 

neutron accumulates over each path are experimentally controlled by 

rotating the phase flag, which changes the optical path length due to the 

flag. After diffraction at the second blade these beams coherently recombine at the third blade and proceed to the O- or H- detector. In insets a, 

b and c are shown the wedges used to create a phase grating across the 

neutron beam and the corresponding images from a position sensitive detector. Each wedge is positioned perpendicular to the beam and 

produces gradients: k1,2 = zk0cosα1,2 + yk0sinα1,2, where k0 is the maximal 

gradient which each wedge can produce in the vertical direction and α1, 

α2 - angles of rotation of the wedge around the neutron beam path. To 

create only vertical gradients we counter-rotate these two wedges: ktot = 

k1 + k2 = 2zk0cosα (α1 = -α2 = α), so the realizable vertical gradients vary 

from -2k0 to 2k0. For imaging, the position sensitive detector is replaced 

by more sensitive 3He detectors.

51
Advances in Measurement

References

3He Spin Filters for Polarized Neutron

Scattering Experiments

W. C. Chen1, J. A. Borchers1, Y. Chen1, R. Erwin1, S. McKenney1, I. Cabrera1,2, C. Broholm2, M. Kenzelmann3, 

T. R. Gentile4, and J. W. Lynn1

Polarized neutron scattering is a powerful probe for a widerange of research fields from physics to biology. Many of t

newest neutron scattering spectrometers have increased beam

angular divergences or wavelength bandwidths in the interest

of larger on-sample neutron fluxes and increased detectable

signal, but this has made it difficult to apply the standard

techniques for polarized beam production and analysis using

reflecting Heusler crystals or super-mirrors. This probl

is now being solved using 3He neutron spin filters (NSFs).

These filters employ nuclear-spin-polarized 3He gas, produced

by optical pumping, and can be used to polarize or analyze

neutron beams because of the strong spin dependence of the

absorption cross section for neutrons by 3He. Due to significa

improvement in their performance during the last several

years, including initial 3He polarizations exceeding 70%, the

use of NSFs has grown in the neutron scattering communi

worldwide. Compared to commonly used polarizers such 

supermirrors and Heusler crystals, NSFs have these advantages:

1) they can polarize a broad wavelength band of neutrons

effectively; 2) they can polarize large area and widely divergent

neutron beams; 3) they are in-line add-on devices and 4) they

can efficiently flip the neutron polarization by reversing the 3He

nuclear polarization [1]. This last capability allows integrati

polarizer and flipper into a single device.

Building upon several years of research and development in the

Physics Laboratory at NIST together with outside collaborations,

the NCNR initiated a program in 2006 to support polarized

neutron beam experiments using 3He neutron spin filters. T

goal of the program is to polarize and/or analyze beams for

neutron scattering instruments where other neutron-polarizing

techniques are inadequate. This goal has been met by applyi

polarized 3He NSF devices to diffuse reflectometry [2], smallangle neutron scattering (SANS) [3], and thermal triple-axis

spectrometry (TAS) [4].

For thermal TAS, 3He spin filters in conjunction with a double

focusing monochromator and analyzer can provide significantly

better neutronic performance and greater versatility in the

selection of energy and polarization compared to Heusler

crystals. We have successfully performed several polarized be

experiments on the state-of-the-art BT-7 TAS using 3He NSFs to

polarize and analyze a 10 cm tall neutron beam. The gener

case involves measuring eight cross sections, four with incoming

neutron polarization perpendicular to the momentum transfer

wave vector Q and four parallel.

Figure 1 shows a result just obtained on this instrument for

a multiferroic system—a material that is both magnetically

ordered and ferroelectric. A recent important discove

in condensed matter physics is that magnetic ordering can

actually induce ferroelectricity, for example when the magnetic

order parameter breaks polar inversion symmetry. In su

magnetoelectric materials it is anticipated that there are two

distinct domains of magnetic order, each carrying opposite

ferroelectric polarization. But how is one to distingui

these magnetic domains, which should be mirror images of

one another?

Polarized neutrons are the answer. Each magnetic doma

should have a definite handedness and this implies that

diffraction from a single domain should polarize the neutron

beam. Figure 1 shows that this is indeed the case for t

magnetoelectric material Ni3V2O8. Upon applying electr

fields in opposite directions, opposite polarization conditions

were indeed associated with the corresponding magnetic

diffraction. This essential information about an importa

class of materials could only be obtained through the use of

polarized neutrons.

For these experiments, the 3He nuclear polarization is initially

above 70 % and is stored in a very homogeneous field provided

by a magnetically shielded solenoid. The decay time constant

for an isolated cell is typically 300 h, which was the case for

the analyzer, but due to stray magnetic field gradients the

time constant at the polarizer was 140 h. We typically refresh

polarized 3He gas after 1 or 2 days on the beam line.

For polarization analysis in diffuse reflectometry, the 3He spin

filter allows much more efficient collection of off-specular

scattering for a broad range of reciprocal space. The use of a 3He spin filter makes polarization analysis practical in SAN

A recent experiment on a magnetic nanoparticle system

showed full polarization analysis in SANS can be done using

a 3He spin filter as both spin analyzer and spin flipper. Userfriendly data reduction software is also under development 

interface with these 3He NSFs.

1NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899

2Johns Hopkins University, Baltimore, MD 21218

3Swiss Federal Institute of Tchnology (ETH), Zurich, Switzerland

4Physics Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899

[1] G. L. Jones et al., Physica B 385-386, 1131 (2006).

[2] W. C. Chen et al., Rev. Sci. Instrum. 75, 3256 (2004).

[3] T. R. Gentile et al., J. Appl. Cryst. 33, 771 (2000).

[4] W. C. Chen et al., Physica B, Physica B 397, 168 (2007

FIGURE 1: Magnetic Bragg scattering from Ni3V2O8 is identified because 

the neutron spin reverses its direction upon scattering. One set of data 

is taken with the incident neutron spins parallel to the momentum 

transfer, (+, -), the other set of data is taken with the incident neutron spins 

antiparallel, (-, +). The direction of the ferroelectric domain is selected by 

applying a voltage of either +300 V or -300 V. The change in the character 

of the magnetic scattering with electric voltage directly and unambiguously demonstrates that the chiral magnetic order and the direction of the 

ferroelectricity are intimately linked in this multiferroic material.

52
Advances in Measurement

Trace Fissionable Material Analysis:

New Metrology Facility

R. M. Lindstrom, R. G. Downing1

1Analytical Chemistry Division, National Institute of Standards and Technology, Gaithersburg, MD 20899

Detecting clandestine fissile material like U-235 andPu-239 is technically challenging in the lab or in the

field because it emits little radiation, and that radiation

is energetically weak. Shipments are easily concealed and

very difficult to detect by conventional methods. However,

when these materials are handled or transported, traces

of uranium or plutonium in the form of particles smaller

than grains of pollen can be left behind. Inspectors for the

International Atomic Energy Agency (IAEA) have used wipecloth collection techniques to search for such evidence of

handling and transport of clandestine treaty-monitored fissile

materials. One of the most sensitive forensic techniques used

to detect and measure the minute remnants of fissionable

uranium and plutonium on these wipes is delayed neutron

activation analysis (DNAA) (see cartoon above). DNAA works

with excellent speed, sensitivity, and specificity, but few such

systems exist worldwide. Overall, DNAA is well-tested, rapid,

specific, matrix-independent, nondestructive, and sensitive.

The technique is sensitive solely to nuclides that fission

with delayed emission of neutrons to give an unambiguous

indication of controlled material, e.g., 233U, 235U, 239Pu, 241Pu, 241Am, 243Cm, 244Cm, 245Cm, 252Cf.

The Nuclear Methods Team in the Analytical Chemistry

Division (ACD) recently installed a DNAA system at the

NCNR. NCNR is an excellent facility to take advantage

of this analytical method because of the intense thermal

flux available with a minimal proportion of fast neutrons.

These highly desirable characteristics mean that

interference from fast-neutron reactions produced from the

ubiquitous presence of thorium and oxygen are negligible.

Consequently, the analysis process is greatly simplified and

detection limits enhanced. At the NIST DNAA facility, less

than one nanogram of fissile species can be detected, and the

analysis requires less than 3 min. Furthermore the system can

process a great variety of sample types that might host the

fissionable particles hidden in volumes as large as 40 mL.

In the last year researchers from Oak Ridge National

Laboratory (ORNL) and our team successfully demonstrated

that the newly installed DNAA system response is strictly

linear over at least a 25-fold concentration range of 235U

(Fig. 1). This demonstrated ability enabled the system to

immediately be used for the analyses of samples from ORNL.

Just recently, the sample transfer system was automated,

leading to increased sample throughput and improved

sensitivity. As the technique is further developed it will 

used to certify the trace

uranium for reference

materials and standard

reference materials.

With the completion

and verification of

the DNAA system,

NIST has a readily

accessible, rapid means

of measuring traces of

fissionable U and Pu

in samples of forensic

interest for homeland

security and producing

standard reference

materials.

FIGURE 1: Plot of neutrons detected in the DNAA counter following 

1 min irradiations as a function of uranium content in the standards.

53
Advances in Measurement

Direct Measurement of the Vertical Coherence

Length of Neutron Waves

D. A. Pushin and D. G. Cory1; M. Arif, D. L. Jacobson and D. S. Hussey2; M. G. Huber3

1Massachusetts Institute of Technology, Cambridge, MA 02139

2Physics Division, National Institute of Standards and Technology, Gaithersburg, MD 20899

3Tulane University, New Orleans, LA 70118

The coherence length in a neutron interferometersystem describes the spatial extent over which quantum

interference may be preserved for the interfering neutron

beams. Increases in the coherence length improve the fringe

visibility (contrast), thus increasing the precision of a measurement. In addition, longer vertical coherence lengths 

neutron interferometry may allow useful implementations

of Fourier Spectroscopy and reflectivity, with applications in

condensed matter and biology [1].

In a neutron interferometer the measured coherence length

is affected by the quality of the single crystal, the momentum

distribution of the incoming neutron beam, and a variety of

environmental contributions such as temperature gradients and vibrations. In this experiment we have explored

the vertical coherence length in a system that is primarily

determined by the incoming beam’s transverse momentum

spread. When this is the case, the coherence length (lc

is limited by Heisenberg’s uncertainty relation lc = 1/(2δk

where δk is momentum spread. To understand this limit, we

study the contrast associated with a wave-packet composed

of incident plane waves corresponding to a distribution

of neutron transverse momentum components varied by

selecting monochromator blades. The coherence length is

a direct measurement of the transverse spatial extent of this

wave-packet.

Measurements for the nine, five, and only the central blade

configurations give us 0.70 nm, 1.2 nm, and 65 nm vertical coherence lengths, respectively, that are related to the

vertical components of the momentum distributions of the

incoming beams. In our measurement the coherence length

is directly obtained by a simple projection and does not

require any post-selection analysis used in earlier measurements done elsewhere [2].

FIGURE 1: (a) A neutron beam, entering at left, is coherently divided via 

Bragg diffraction on the 1st blade of the neutron interferometer into 

paths I and II. The phases which the neutron accumulates over each path 

are experimentally controlled by rotating the phase flag. (b) In one of the 

paths we install two 45° prisms which form a cube when unseparated. 

By horizontally separating the prisms by L we shift the neutron beams in 

paths I and II vertically (∆z) with respect to each other. We observe a loss

in contrast with displacement, which we measure with the help of phase 

shifter (shown in (a)). (c) Enlarged view of the neutron beam as it exits 

the prism.

FIGURE 2: (a) the contrast with all nine Bragg reflecting pyrolitic graphite 

crystal blades of a focusing monochromator (not shown) contributing to 

the incident beam; (b) the contrast for the central five blades; and (c) the 

contrast for the central blade. The contrast length increases as we narrow 

the momentum distribution of the incoming neutron beam by reducing 

the number of blades. Notice that in the narrowest case the contrast 

remains up to 100 nm vertical separation of the beam paths. The solid 

lines are contrast curves obtained by approximating the wave-function of the neutrons as a plane wave and integrating over the vertical 

momentum distribution.

[1] H. Rauch, Physica B 213-214, 830 (1995).

[2] H. Rauch, H. Wölwitsch, H. Kaiser, R. Clothier, and

S. A. Werner, Phys. Rev. A 53, 902 (1996).

References

54
Neutron Source Operations

NCNR 2007 ACCOMPLISHMENTS AND OPPORTUNITIES

The NIST reactor (NBSR) operated for 256 full power

(20 MW) days or 99 % of the scheduled time during FY2007.

A typical operating year consists of seven cycles. A cycle

has 38 d of continuous full power operation, followed by

11 d of shutdown for maintenance, refueling, and startup

preparations. The cold source reliability continues to be

remarkable—failing to be ready to operate for only 2 h out

of 256 operating days. This represents an availability of over

99.99 %. The strong performance of the neutron scattering

program owes much to this outstanding record of safe and

reliable performance of the reactor and cold source.

A major focus for the Reactor Operations and Engineering

Group is recruiting and training new staff as we face an

increased rate of turnover due to retirements. This year, our

recruiting focused on senior reactor operators, a nuclear

engineer, and an electrical engineer. A senior reactor

operator was hired and licensed.

Facility Improvements

Another major activity of

the Reactor Operations and

Engineering Group is to

continuously improve the plant

in order to sustain operational

efficiency and maintain high

reliability. This year saw a

tremendous amount of work

accomplished in this area—a remarkable achievement given

the heavy demands on the staff from the full operating

schedule. Highlights include:

•	 Upgrade of the RT-2 in-core pneumatic experimental

facility. The new system includes a replacement of

its control circuit to accommodate the addition of

an anticipated local detector to which samples can

automatically be routed.

•	 A redesigned and rebuilt drive assembly for the

regulating rod (reactor automatic fine control rod)

	 to improve performance.

•	 Improvements to the fuel head assemblies and their

handling procedures. We developed new, titanium fuel

heads to avoid aluminum galling problems, and fuel

manipulation device handling protocols have been

physically reorganized to protect delicate tools.

•	 Continuation of a major program of upgrades to the

reactor building ventilation system.

•	 Continuation of modernization of key components in

the electrical systems, with replacement of the secondary

cooling system switchboards.

•	 A test setup designed and built that allows simulating

alternative modes of pumping coolant through a single

isolated thermal shield cooling loop. This setup will be

deployed to investigate whether coolant can be pumped

though a cooling loop surrounded by vacuum. Such an

approach would allow rapid

detection of flow problems.

The setup is designed

to monitor temperature

differences, volumetric flow,

pressure drop, dissolved

oxygen, pH, and radiation

dose. Furthermore, a variety

of flow/pressure conditions

can be created using a

combination of outputs from

vacuum and pressure pumps.

•	 An update and re-organization of the training program

for reactor operators in anticipation of new challenges

to NCNR recruitment, licensing, and retention of

reactor operators.

Control Room Upgrade

The NCNR Expansion Project, which

began this year, includes several

projects aimed at upgrading or

replacing specific plant systems to

improve operational efficiency and

reliability. As part of this effort, and

in collaboration with engineers at

Brookhaven National Laboratory, we

began an upgrade project to modernize

the reactor control room. This complex

project is beginning with a system-by-system analysis of the

NCNR control systems so that an efficient design, testing,

and installation plan can be developed. A major focus of

the effort will be to enhance the interface between the

control systems

and the reactor

operations staff,

and to minimize

disruption of

the NCNR

operational

schedule.

The new

system should

also improve

maintenance and troubleshooting activities.

Relicensing

The operating license for the NBSR expired on May 16, 2004

and U.S. Nuclear Regulatory Commission (NRC) regulations

allow for continued operation after submittal of a timely

application for license renewal, which was done on April 9,

2004. Ongoing work continues within the group in support

of completing the license renewal as the application is

actively processed by the NRC.

Paul Liposky shows a 

redesigned (titanium) fuel 

head assembly.

Dan Keyser, Tony Norbedo and Jim Beatty developed 

the thermal shield coolant pumping simulator.

Barry Caudle views a diagram of the Control 

Room upgrade design.

55
Facility Developments

Engineering Developments and Performance 

of the MACS

The Multi-Axis Crystal Spectrometer (MACS) is a high

intensity cold neutron spectrometer that will greatly expand

access to atomic scale dynamic processes in condensed

matter. The fabrication and installation of this instrument

has progressed to the point where the accomplishment of

design goals can be assessed and reported here.

The incident beam line was installed with a provisional fixed

cooled beryllium filter. The monochromatic beam focusing

mechanism, which involves 27 stepping motors, performed

as intended. Indeed, the very first remote command to

focus the neutron beam on the sample was successful, and

Fig. 1 shows the energy-dependent flux on the sample. The

conservative project goal of 108 neutrons/cm2/s was easily

surpassed. However, there is no magic: The measured flux

numbers are fully consistent with the detailed Monte Carlo

simulation (shown as a solid line in Fig. 1). Comparisons of

these results with recent flux measurements for the SPINS

cold neutron triple axis spectrometer show that the incident

beam flux on MACS is more than a factor of 40 greater

than that of the older instrument, an observation attributed

largely to the greater active area of the monochromator

(1428 cm2 on MACS as compared to 75 cm2 on SPINS).

To maximize its efficiency, MACS is geometrically compact,

making for tight quarters around the sample. However,

user safety and user access, particularly to the most

advanced features of MACS, were also essential design

criteria. Figure 2 shows the design for a slit and automatic

attenuator exchange system for the incident beam. Through

a combination of piezoelectric and pneumatic drive

mechanisms, this device reconciles the conflicting demands

of fully automated access to apertures and attenuation close

to a high field magnet in a package only 52 mm thick.

The MACS detector system consists of 20 channels, each of

which subtends a solid angle of 0.1 sr at the sample. Figure

3 shows the stainless steel base of the detector system. The

plate will carry 4500 kg (10 000 lb) of polyethylene and

boron carbide loaded with polyurethane to create a quiet

environment for the forty 3He neutron detectors. To simplify

the interface to this mobile detector system, compartments

below the plate accommodate the wide range of electronic

support systems needed for operation. Also visible on the

figure is the sample positioning system which provides full

gimballing capabilities for a 400 kg sample environment

system. By placing the actuating stepping motors more than

750 mm below the beam position these can remain in place

and even operate while the sample is subjected to a high

magnetic field.

The central functional element in each channel of the

detector system is the double crystal analyzer (DXAL). A

single stepping motor positions the device for scattered

beam energy analysis in the range from 2.5 meV to 15 meV.

Transmission through the DXAL is improved through the use

of 84 ́ graphite, 40 % coarser than the 60 ́ graphite on the

monochromator. This choice ensures similar elastic energy

resolution before and after the sample despite the different

geometries. A direct comparison to the SPINS 25 ́ analyzer

shows identical integrated transmission at a somewhat

coarser energy resolution (δE = 0.42 meV for the DXAL

compared to 0.28 meV for the SPINS analyzer at a fixed final

energy of 5 meV and without collimation).

FIGURE 1: MACS flux on sample versus energy. The sample cross section 

was a rectangle 2 cm wide and 4 cm tall. The neutron flux for E < 5 meV 

were measured with a Be filter placed after the source. Measurements 

for E > 5 meV were taken without the Be filter and were corrected fo

λ/2 contamination. The solid lines are Monte Carlo Simulations. All beam 

line components from source to the sample position were simulated, 

excluding the filters. The error bars represent a conservative estimate of 

systematic errors.

FIGURE 2: CAD Representation of the design for the MACS Pre-Sample 

Optics system to be installed between the Supermirror Guide and the 

Sample Position. The Pre-Sample Optics system will provide the capability to monitor the neutron flux exiting the supermirror guide, insert attenuators in the incident beam, and define the size of the beam to better 

match the size of the sample. The selection of attenuator and size of the 

aperture are remotely controlled by computer.

56
NCNR 2007 ACCOMPLISHMENTS AND OPPORTUNITIES

With over 28 Physical Review Letters and 5 articles in

Science and Nature to its name since 2000, the scientific

productivity of SPINS has been remarkable. Combining forty

times more flux on sample and four times greater detector

system solid angle, MACS promises to improve upon that

record to usher in an exciting new era for cold neutron

spectroscopy. In particular, the new instrument will allow

scientists to tackle the many important problems in modern

condensed matter physics in which only small samples

are available or in which extreme sample environment

conditions that limit sample size are required.

Instrument Control Software

The instrument control software team is deploying a

modernized data acquisition and instrument control system

featuring a common command set and an easy-to-use

graphical user-interface (GUI). Its purpose is to provide

NCNR users and staff with state-of-the-art in instrument

control having a standardized look and feel. The Instrument

Control Environment (ICE) system also features real-time

updates of motor positions, instrument status, and data

visualization. Over the past year the team has started the

process of changing all of NCNR’s neutron scattering

instruments from the older instrument control/data

acquisition platforms to the modern Instrument Control

Environment (ICE).

Data Visualization and Analysis

DAVE 2, a major re-design of DAVE, has now been deployed

in an experimental version. The purpose of this release is

to enable users to try out the new capabilities and provide

feedback. This version of DAVE contains many new features

such as session management, better support for handling

multiple datasets, improved document/view architecture

(multiple ways to view a document), widespread messaging

(allowing seamless updating of graphs as data is changed,

for example), and enhanced usability with multiple levels of

undo/redo functionality. DAVE 2 is publicly available from

the web at http://www.ncnr.nist.gov/dave/download.html.

We are also developing the next generation of reflectometry

analysis software. Now available is a parallel global search

application which can simultaneously fit x-ray, neutron, and

polarized neutron reflectometry data. Our reflectometry

models allow a combination of uniform and free form

density profiles at different depths in the sample, with

constraints on the range of possible profile values. While

not yet ready for general release, early versions are available

on site at the NCNR (http://www.ncnr.nist.gov/dva)

and at the Spallation Neutron Source. The underlying

search framework is not specific to reflectometry, and

will eventually support diffraction, small angle neutron

scattering, and inelastic scattering models. This work is

funded in part by the DANSE project (NSF DMR-0520547).

FIGURE 3: Mechanical Engineers Zheng Huang (University of Maryland) 

and Jim Moyer (NCNR) perform a dimensional check during assembly 

of the 6-axis sample positioning stage and 20-channel crystal analyzer/

detector system for the MACS Spectrometer. Following complete assembly and testing, the system will be deployed at NG-0.

FIGURE 4: Freeform fits to the subsurface magnetic structure of a spin 

valve. Since the reflectometry inverse problem is not uniquely solvable, 

it is important to see the variety of solutions which fit the data. That 

these profiles are consistent gives us confidence that we have found 

the best solution within the constraints of the model.

Designed for adaptability, flexibility, and extensibility, ICE

consists of a modular code base forming a common core

and instrument-specific extensions meant to serve both

current and future needs. These software characteristics are

intended to allow rapid modernization and standardization

of controls of all NCNR instruments.

The new BT-7 triple-axis spectrometer is the first instrument

to be controlled with ICE. The development for BT-7 is

nearly complete and the graphical user interface exposes

nearly all of the functionality of the instrument control

software. The next step is to deploy ICE on  the MACS an

SPINS instruments to achieve the goal of standardizing

controls across triple-axis spectrometers.

57

Laboratory Renovations and Developments

The NCNR continues to work toward providing better laboratory

facilities for our users. One of the existing chemistry laboratories

was successfully renovated and re-equipped. This improvement

provides more space for researchers requiring sample

preparation facilities in the general area of materials chemistry.

One of the most visible changes in user amenities is the

renovation of one of the user offices. The original layout of

the user office and terminal room was re-designed to provide

essential infrastructure to an optimal number of occupants. As

a result of these changes the user area now accommodates twice

the number of guest researchers.
Serving the Science and Technology Community

FIGURE 1: Research Participants at the NCNR in 2007.

The mission of the NIST Center for Neutron Research is to

assure the availability of neutron measurement capabilities

to meet the needs of U.S. researchers from industry, academia and from other U.S. government agencies. To carry

out this mission, the NCNR uses several different mechanisms to work with participants from outside NIST, including a competitive proposal process, instrument partnerships,

and collaborative research with NIST.

Proposal System

Most of the time on NCNR instruments is made available

through a competitive, peer-review proposal process. The

NCNR issues calls for proposals approximately twice a year.

Proposals are reviewed at several different levels. First, expert external referees evaluate each proposal on merit and

provide us with written comments and ratings. This is a very

thorough process where several different referees review

each proposal. Second, the proposals are evaluated on technical feasibility and safety by NCNR staff. Third, we convene

our Beam Time Allocation Committee (BTAC) to assess

the reviews and to allocate the available instrument time.

Using the results of the external peer review and their

own judgment, the BTAC makes recommendations to the

NCNR Director on the amount of beam time to allocate

to each approved experiment. Approved experiments are

scheduled by NCNR staff members in consultation with

the experimenters.

The current BTAC members are:

•	 Ramanan Krishnamoorti (chair, University of Houston)

•	 Andrew Allen (NIST Ceramics Division)

•	 Collin Broholm (Johns Hopkins University)

•	 Ken Chen (Sandia National Laboratories)

•	 Mark Foster (University of Akron)

•	 Michael Kent (Sandia National Laboratories)

•	 Joanna Krueger (University of North Carolina

at Charlotte)

•	 Young Lee (Massachusetts Institute of Technology)

•	 Raul Lobo (University of Delaware)

•	 Robert Leheny (Johns Hopkins University)

•	 Lee Magid (University of Tennessee, Knoxville)

•	 Janna Maranas (The Pennsylvania State University)

•	 Stephan Rosenkranz (Argonne National Laboratory)

•	 Dawn Sumner (University of California Davis)

•	 Michael Toney (Stanford Synchrotron Radiation

Laboratory)

Partnerships

The NCNR may form partnerships with other institutions

to fund the development and operation of selected instruments. These partnerships, or “Participating Research

Teams,” may have access to as much as 75 % of the available beam time on the instrument depending on the share

of total costs born by the team. A minimum of 25 % of

the available beam time is always made available through

the NCNR proposal program to all users. Partnerships are

negotiated for a fixed period (usually three years) and may

be renewed if there is mutual interest and a continued need.

These partnerships have proven to be an important and

effective way to expand the research community’s access to

NCNR capabilities and have been very successful in developing new instruments.

Collaboration with NIST

Some time on all instruments is available to NIST staff in

support of our mission. This time is used to work on NIST

research needs, instrument development, and promoting

the widespread use of neutron measurements in important

research areas, particularly by new users. As a result of these

objectives, a significant fraction of the time available to NIST

staff is used collaboratively by external users, who often take

the lead in the research. Access through such collaborations

is managed through written beam time requests. In contrast

to proposals, beam time requests are reviewed and approved

internally by NCNR staff. We encourage users interested in

exploring collaborative research opportunities to contact an

appropriate NCNR staff member.

Research Participation at the NCNR

The NCNR continued its strong record of serving the U.S. research

community this year. Over the 2007 fiscal year, 2258 research

participants benefited from use of the NCNR. (Research participants include users who come to the NCNR to use the facility as

well as active collaborators, including co-proposers of approved

experiments, and co-authors of publications resulting from work

performed at the NCNR.) Research participants represented 236

external institutions, including 137 U.S. universities, 40 U.S. national laboratories, and 59 U.S. industries. The NCNR is a national

facility, with participantsfrom 40 states, DC, and Puerto Rico.

2007 NCNR Proposal Program

Two callsin the past year resulted in the submission of 629 proposals, a record number, of which 373 were approved and received

beam time. The oversubscription, i.e., the ratio of days requested

on all proposals to the days available, was 2.2 on the average, but as

high as 2.9 for specific instrumentsin one call. Proposal demand

has grown constantly since the NCNR first began accepting proposals in 1991, and has doubled in the pastsix years. The following

table showsthe data for several instrument classes.

58
NCNR 2007 ACCOMPLISHMENTS AND OPPORTUNITIES

Instrument class Proposals

Days

requested

Days

allocated

SANS and USANS 288 1038 448

Reflectometers 87 707 382

Spectrometers 221 1560 661

Diffraction 11 35 24

Imaging 22 108 70

Total 629 3448 1585

User Group Conducts Survey

The NCNR Users Group (NUG) provides an independent

forum for all facility users to raise issues to NCNR

management, working through its executive officers to carry

out this function. During 2007, it conducted a comprehensive

online survey of user satisfaction and concerns, eliciting

260 responses with many useful comments on areas such as

instrument quality and problems, sample environment, data

analysis software, and user laboratories. The survey input will

guide the NCNR to make some significant improvements to

user support. In late 2007, the NUG will conduct its second

online election of officers. The current Executive Committee

consists of Nitash Balsara (University of California, Berkeley,

chair), Kalina Hristova (Johns Hopkins University), Tonya

Kuhl (University of California, Davis), Robert Leheny (Johns

Hopkins University), and Stephan Rosenkranz (Argonne

National Laboratory).

Panel of Assessment

The major organizational components of NIST are evaluated periodically for quality and effectiveness by the National

Research Council (NRC), the principal operating agency

of both the National Academy of Sciences and the National

Academy of Engineering. A panel appointed by the NRC

reported on the NIST Center of Neutron Research in early

2007. Their findings are summarized in a document that

may be viewed online at http://books.nap.edu/openbook.

php?record_id=12010&page=R1

The panel members included Philip Pincus of the University

of California, Santa Barbara (chair), Tonya Kuhl, University

of California, Davis, Herbert Mook, Oak Ridge National

Laboratory, V. Adrian Parsegian, National Institute of Child

Health and Development, R. G. Hamish Robertson, University of Washington, Kenneth C. Rogers, Nuclear Regulatory

Commission (retired), and Barbara Wyslouzil, the Ohio

State University.

The Center for High Resolution Neutron 

Scattering (CHRNS)

The CHRNS is a national user facility that is jointly funded

by the National Science Foundation and the NCNR. Its

primary goal is to maximize access to state-of-the-art neutron

scattering instrumentation for the research community. It

operates six neutron spectrometers and diffractometers at

the NCNR, enabling users from around the nation and the

world to observe dynamical phenomena involving energies from approximately 30 neV to approximately 100 meV,

and to obtain structural information on length scales from

1 nm to approximately 10 μm. A more detailed account 

CHRNS activities may be found in another section of this

report.

Partnerships for Specific Instruments

NG-7 SANS Consortium

A consortium that includes NIST, the Industrial Partnership for Research in Interfacial and Materials Engineering (IPRIME) led by the University of Minnesota, and the

ExxonMobil Research and Engineering Company, operates,

maintains, and conducts research at the NG-7 30 m SANS

instrument. The consortium uses 65 % of the beam time on

this instrument, with the remaining 35 % allocated to the

general scientific community through the NCNR’s proposal

system. Consortium members conduct independent research programs primarily in the area of large-scale structure in soft matter. For example, ExxonMobil has used this

instrument to deepen their understanding of the underlying

nature of their products and processes, especially in the

fields of polymers, complex fluids, and petroleum mixtures.

NIST / General Motors – Neutron Imaging

An ongoing partnership between General Motors and

NIST has resulted in an exciting collaboration employing

neutron imaging to visualize the operation of fuel cells for

automotive vehicle applications. Neutron imaging is an ideal

method for observing the movement and behavior of water

in proton exchange membrane fuel cells, a key to developing hydrogen-powered cars that employ such cells instead of

internal combustion engines as their central power source.

In the past year, the spatial resolution of the technique has

been improved tenfold. Experiments were performed to

simulate the operation of stacks of cells, a necessary advance

towards development of practical fuel cell vehicles.

Interagency Collaborations

The Smithsonian Institution’s Nuclear Laboratory for

Archeological Research is part of the Anthropology

Department at the National Museum of Natural History. It

has had a productive 30 year partnership with the NCNR,

during which time it has chemically analyzed over 35,000

archaeological artifacts by Instrumental Neutron Activation

Analysis (INAA), drawing extensively on the collections

of the Smithsonian, as well as on those of many other

institutions in this country and abroad. Such chemical

analyses provide a means of linking these diverse collections

together in order to study continuity and change involved in

the production of ceramic and other artifacts.

The Center for Food Safety and Applied Nutrition, U.S.

Food and Drug Administration (FDA), directs and maintains

a facility at the NCNR that provides agency-wide analytical

support for food safety and food defense programs. Neutron

activation (instrumental, neutron-capture prompt-gamma,

and radiochemical), x-ray fluorescence spectrometry, and

low-level gamma-ray detection techniques provide diverse

multi-element and radiological information about foods

and related materials. Ongoing studies include cryogenic

homogenization of foods, preparation of an in-house

reference material, improved detection capabilities for

iodine, mercury, and other toxic and nutritional elements in

foods, and rapid screening of food products for dangerous

levels of cadmium, lead, mercury, and other toxic elements.

59
The Center for High Resolution Neutron

Scattering (CHRNS)

CHRNS is a national user facility that is jointly funded by

the National Science Foundation, through its Division of

Materials Research, and by the NCNR. The primary purpose

of this partnership is to maximize access to state-of-the-art

neutron scattering instrumentation for the research community through the NCNR’s proposal system. Proposals to

use the CHRNS facilities are critically reviewed on the basis

of scientific merit and/or technological importance.

The core mission of CHRNS is fourfold: (i) to develop and

operate neutron scattering instrumentation, with broad

application in materials research, for use by the general

scientific community; (ii) to promote the effective use of the

CHRNS instruments by having an identifiable staff whose

primary function is to assist users; (iii) to conduct research

that advances the capabilities and utilization of CHRNS

facilities; and (iv) to contribute to the development of

human resources through educational and outreach efforts.

Scattering Instruments and Research

CHRNS currently operates:

1.	 the 30-meter Small Angle Neutron Scattering (SANS)

instrument at NG-3,

2.	 the Ultra-Small Angle Neutron Scattering (USANS)

instrument at BT-5,

3.	 the Spin-Polarized Inelastic Neutron Scattering (SPINS)

spectrometer at NG-5,

4.	 the Disk Chopper Spectrometer (DCS) at NG-4,

5.	 the High Flux Backscattering Spectrometer (HFBS) at

NG-2, and

6.	 the Neutron Spin-Echo (NSE) spectrometer at NG-5.

The small angle scattering instruments supported by

CHRNS provide structural information over length scales

from ≈ 1 nm to ≈ 10 μm. The spectrometers collective

yield dynamical information over time scales from

≈ 3×10-14 s to ≈ 10-7 s (energy scales from ≈ 100 meV to

≈ 30 neV). These wide ranges of accessible distances and

times support a very diverse scientific program, allowing

researchers in materials science, chemistry, biology, and

condensed matter physics to investigate materials such as

polymers, metals, ceramics, magnetic materials, porous

media, fluids and gels, and biological molecules.

In the February 2007 Call for Proposals, 224 were received

for the six CHRNS-operated instruments, and 123 were

awarded beam time. Of the 1214 days requested, the Beam

Time Allocation Committee approved 531. Roughly half of

the users of neutron-scattering techniques at the NCNR use

CHRNS-funded instruments, and about one third of NCNR

publications (see the “Publications” section on

p. 64) over the current one-year period are based on research

performed using these instruments. In 2006 more than 25

Master’s and Ph.D. theses were completed using results from

CHRNS-sponsored instruments.

Scientific Support Services

An important ingredient of the CHRNS operation is its support of staff members whose primary responsibilities are to

provide users with services that are frequently essential to the

success of neutron scattering investigations. One such service

is the provision and operation of an expanding range of sample environment equipment. The sample environment team

also assists users through the production of web-based videos

that serve to instruct new users in the proper procedures for

handling various types of equipment. The team is responsible

for all aspects of production thereof, including writing, filming, and editing. This past year they produced a new video on

measuring the cryogen levels in a variety of cryostats.

Other services provided are the maintenance of several wellequipped user laboratories, and the development, documentation and maintenance of data reduction, visualization, and

analysis software through the DAVE project. DAVE is a suite

of programs that gives users the ability to rapidly reduce,

examine and display their experimental data in order to better understand it (http://www.ncnr.nist.gov/dave/).

DAVE may be downloaded free of charge from the website

either as a binary executable with an embedded runtime license or as the complete source code. The DAVE project has

lately been expanded to include support for spectrometers at

the Paul Scherrer Institute (Switzerland). A major redesign,

known as DAVE 2, is currently under development.

FIGURE 1: DCS data analyzed using DAVE. (See highlight on pp. 22-23.)

60
NCNR 2007 ACCOMPLISHMENTS AND OPPORTUNITIES

FIGURE 3: 2007 SURF students (left to right): Harry Bullen, Katherine Ku, Justin Poelma, Christopher 

Dosch, Junbo Park, Gina Polimeni, Ryan Hensarling, Rebecca Teague and David Tighe.

Education and Outreach

CHRNS supports education and outreach programs whose

purpose is to strengthen and expand the United States’ neutron community. In particular, CHRNS sponsors a variety of

activities designed to help train the next generation of neutron scientists. Every year since 1995 the NCNR has hosted a

week-long summer school that has proven to be a very effective way of introducing graduate students and postdoctoral

researchers to neutron scattering. The material covered at

the summer school alternates between small angle scattering

and reflectometry in even-numbered years and spectroscopy

in odd-numbered years.

The 2007 Summer School on Methods and Applications of

Neutron Spectroscopy, fully supported by CHRNS, attracted

83 applicants for the 32 available places. The students who

attended the school came from 27 different North American

institutions. They came from diverse backgrounds ranging

from chemistry, physics, and materials science, to polymer

science, complex fluids, and biology. Most of them were

graduate students; there were several postdocs and one

assistant professor.

Following introductory lectures, the students were separated into four groups to be guided by staff through a series

of experiments using different instruments. They studied

quantum rotations in methyl iodide using backscattering and neutron vibrational spectroscopy; the magnetic

phase transition and spin fluctuations in the geometrically

frustrated spinel CdCr2O4 using triple-axis spectrometry; gas

adsorption in a metal-organic framework using time-of-flight

spectroscopy; and shape fluctuations of surfactant shells in a

microemulsion with neutron spin-echo spectroscopy. On the

final day of the school the student groups gave short presentations describing the results of their experiments.

CHRNS staff members participated in the NIST Summer

Undergraduate Research Fellowship (SURF) program. This

year, the 14th year of the program, we hosted nine undergraduate students each of whom had the opportunity to

work directly with scientific staff members. Areas of research

ranged from biophysics and green chemistry to computer

science. Typically the students prepared samples, performed

neutron scattering experiments, and developed computer

programs for data analysis. The students expressed how

important their experiences had been in helping them understand the nature of research and the way scientists

approach problems.

This year NIST hosted the first NIST-Montgomery County

(MD) Public School Summer Institute for Middle School

Science Teachers, a new program that brings teachers to

NIST for two weeks in order to gain a better understanding of the scientific process. Twelve science teachers from

Montgomery and Howard Counties took part. At the NCNR,

the teachers learned how neutrons are produced and used

to investigate the structures of materials. They were also

shown how to grow crystals of alum, a crystal-growing project

suitable for middle school students. The day concluded

with a tour of the facility and a discussion of the structure

and expected powder diffraction

pattern of alum. CHRNS Director

Dan Neumann frequently leads

tours of the NCNR facility for

undergraduate and graduate students. We also design and present

segments of the “Adventures in

Science” program for middle

school students, which occurs

at NIST on Saturday mornings

between October and March.

CHRNS staff members also serve

as judges at local science fairs.

FIGURE 2: NCNR 2007 Summer School participants.

61
David L. Jacobson, of the Ionizing Radiat

Division, Physics Laboratory has received the

(Washington, D.C.) Downtown Jaycees 2007

Arthur S. Flemming Award. The Flemm

Awards honor outstanding federal em

with three to 15 years of public service

experience.

Muhammad Arif of the Ionizing Radiatio

Division of the Physics Laboratory received the

2007 DOE Hydrogen Program R&D Award

Recognition of Outstanding Achievemen

Fuel Cell R&D at the DOE Hydrogen Prog

Annual Merit Review.The award recognizes t

major contributions Dr. Arif and his colleagues

have made in applying neutron imaging to

operating fuel-cells, and for developing a dedicated facility at the

NCNR available to the entire U.S. fuel-cell industry.

NIST Standards Alumni Association Por

Gallery of Distinguished Alumni in 20

added NCNR’s J. Michael 

For outstanding research accomplishments and 

for visionary leadership transforming the NIST 

Center for Neutron Research into the foremost 

neutron research facility in the United States.

and John J. Ru

For outstanding scientific achievements and for 

vision and leadership in developing the NIST 

Center for Neutron Research.

A DOC Silver Medal in the Scientific and EngineeringAchieve

Categorywas awarded in 2007 to the team ofBarry J.Bauer,Research

Chemist, MSEL;Ronald L.Jones, MaterialsResearch Engineer,

MSEL; Eric K. Lin, SupervisoryChemical Engineer, MSEL; Da-We

Liu,ResearchChemist, MSEL; Christopher L. Soles, M

Research Engineer, MSEL; Wen-Li Wu, NISTFellow, MSEL.Th

team isrecognized for development of innovative, powerful methods to measure 

the structure and properties of nanoporous low dielectric constant thin films 

essential for next-generation electronics. 

Awards 2007

John J. Rush of the NCNR has b

appointed Fellow of the Neutron Scat

Society of America. His citation read

a career of visionary scientific leadership in 

promoting the field of neutron science in the U.S.”

Peter Gehring of the NCNR has 

appointed Fellow in the American Phy

Society: “For major contributions to 

understanding of the lattice dynamics of relaxor 

ferroelectrics, and elucidating the nature of the 

spin dynamics of cuprate oxides by means of 

neutron scattering.”

The PNAS Cozzarelli 2006 paper-of-theyear award in the category of En

and Applied Sciences was announced at the

Proceedings of the National Academy of

Sciences Editorial Board Meeting in April

2007 to be The violation of the Stokes–Einstein 

relation in Supercooled Water by Sow-Hsin Chen,

Francesco Mallamace, Chung-Yuan Mo

Matteo Broccio, Carmelo Corsaro, Antonio Faraone, an

Liu. Faraone is an instrument-responsible for the neutron

spin-echo spectrometer at the NCNR.

Shannon Watson of the NCNR was awa

the 2007 Best Dissertation Award by 

National Society of Black Physicists for her

dissertation from the College of William and

Mary entitled: “Impact of Large-Scale Substrate 

Roughness on Giant Magnetoresistive Thin Films.”

The award recognizes research conducted

as part of a dissertation and includes a

certificate and $500.

Hui Wu of the NCNR was selected for the

NIST chapter of Sigma Xi’s 2007 outstandin

poster award for her presentatio

“Investigation of Novel Systems for Hydrogen 

Storage: Synthesis, Neutron Scattering, and Firstprinciples Calculations.”

James McIver of the NCNR, a recent gradu

of Johns Hopkins University and past

president of the Johns Hopkins University

Society of Physics Students, was recognized

as an outstanding undergraduate stud

majoring in Physics by the Donald E. 

Memorial Award in May 200

62

Eric Lin Chris       We
NCNR 2007 ACCOMPLISHMENTS AND OPPORTUNITIES

James S. Clark, Health Physicist, office of 

Chief Human Capital Officer/Office of the

Director, was awarded a DOC Bronze M

in 2007. Mr. Clark’s commitment to excellence and 

his 22 year management of the NIST Radioactive 

Waste Program have earned him great respect and 

appreciation among his NIST colleagues. He is 

recognized in the Health Physics industry as an expert resource in the 

field of radioactive waste management, handling and disposition. 

Yamali Hernandez, Physical Scientis

NCNR, was awarded a DOC Bronze M

in 2007. Hernandez is recognized for her 

leadership in modernizing and expanding the 

NIST Center for Neutron Research (NCNR) user 

laboratories, which now set the standard for user 

service both nationally and internationally.

David L. Jacobson, Physicist, Phys

Laboratory, was awarded a DOC Bronze M

in 2007. Jacobson has taken a lead role in the 

development of the world’s most advanced neutron 

imaging station to study water transport in fuel 

cells.

Darrin J. Pochan of the University

Delaware’s Materials Science Department

has been named the 2007 recipient of the

American Physical Society’s John H. Dill

Medal “For advancing our understanding of

the physics of assembly and chain conformation 

of synthetic polypeptides.” The prize bestows

a certificate, a bronze medal, a $2000

award, and travel expenses to attend the APS

meeting for the presentation. Darrin often uses the NCNR

facility for his work.

A. Brooks Harris of the University 

Pennsylvania has been named the 2007

recipient of the American Physical Society’s

Lars Onsager Prize “For his many contributions t

the statistical physics of random systems, including 

the formulation of the Harris criterion, which has 

led to numerous insights into a variety of disordered 

systems.” The prize bestows a certificate and a

$15,000 award. Brooks often visits the NCNR to collaborate

with Taner Yildirim.

Wen-li Wu, NIST fellow and member o

the Polymers division of MSEL, has been

appointed Fellow by the American C

Society Division of Polymeric M

Science and Engineering at their 200

meeting. Wu was awarded a DOC Gold

Medal (1992), the Samuel Wesley Stratton

Award in 1997 and William P. Slichter Award in 2001. He

became a fellow of the American Physical Society in 1992.

Megan Robertson (previously Ruegg),

Ph.D. recipient at UC Berkeley from Nitash

Balsara’s group, is the winner of the 2007

ICI Student Award in Applied Po

Science given by the Amer

Society. Megan has done much of he

at the NCNR. The award is sponsored by the

Polymer Education Committee of the ACS and the Divisions

of Polymeric Materials: Science and Engineering and Polymer

Chemistry.

Stephanie Moyerman, a recent gradu

Harvey Mudd College and 2005 recipient

of a NIST SURF award, was presented with

the LeRoy Apker Award for Undergr

Physics Achievement by th

Physical Society at its 2007 March Me

She was cited for “her research on the mechanisms governing the 

magnetic field response of spin valves” some of which was done

using neutron reflectometry at the NCNR. Stephanie 

beginning graduate work in physics at UC Berkeley as a Bell

Labs Graduate Research Fellow and NSF Fellow.

Stephen Wilson was awarded the FowlerMarion Outstanding Gradua

Award by the University of Tennessee Physics

Department for outstanding Ph. D thesis

work and citizenship. Wilson performed

measurements used in his dissertation

at the NCNR. Stephen also won the the

American Physical Society Topical Group on M

its Applications (GMAG) Student Dissertation Award

entitled him to present an invited talk at APS March meeting

in Denver, receive a $500 prize and $250 in travel expenses to

attend the meeting.

63
Publications: August 1, 2006 to July 31, 2007

Abdul-Fattah, A.M., Truong-Le, V., Yee, L., Nguyen, L., Kalonia,

D.S., Cicerone, M.T., Pikal, M.J., “Drying-Induced

Variations in Physico-Chemical Properties of Amorphous

Pharmaceuticals and Their Impact on Stability (I): Stability of

a Monoclonal Antibody,” J. Pharm. Sci., in press. (chrns)

Abdurashitov, J.N., Gavrin, V.N., Matushko, V.N., Nico,

J.S., Shikhin, A.A., Thompson, A.K., Veretenkin, I.E.,

“Development of a Segmented Fast Neutron Spectrometer,”

Phys. Atom. Nucl. 70 (1), 133 (2007).

Agrawal, S.K., Sanabria-DeLong, N., Jemian, P.R., Tew, G.N.,

Bhatia, S.R., “Micro- to Nanoscale Structure of Biocompatible

PLA-PEO-PLA Hydrogels,” Langmuir 23 (9), 5039 (2007).

(chrns)

Akman, N., Durgun, E., Yildirim, T., Ciraci, S., “Hydrogen Storage

Capacity of Titanium Met-Cars,” J. Phys.: Condens. Matter 18

(41), 9509 (2006).

Allen, A.J., Thomas, J.J., “Analysis of C-S-H Gel and Cement Paste

by Small-Angle Neutron Scattering,” Cem. Concr. Res. 37 (3),

319 (2007). (chrns)

Allen, A.J., Thomas, J.J., Jennings, H.M., “Composition and Density

of Nanoscale Calcium-Silicate-Hydrate in Cement,” Nature

Mater. 6 (4), 311 (2007). (chrns)

Anghel, V.N.P., Kucerka, N., Pencer, J., Katsaras, J., “Scattering

From Laterally Heterogeneous Vesicles. II. The Form Factor,”

J. Appl. Cryst. 40 (3), 513 (2007).

Ashish, Paine, M.S., Perryman, P.B., Yang, L., Yin, H.L., Krueger,

J.K., “Global Structure Changes Associated with Ca2+

– Activation of Full-Length Human Plasma Gelsolin,” J. Biol.

Chem., in press.

Augustus, A.M., Reardon, P.N., Heller, W.T., Spicer, L.D.,

“Structural Basis for the Differential Regulation of DNA by

the Methionine Repressor MetJ,” J. Biol. Chem. 281 (45),

34269 (2006).

Azimonte, C., Cezar, J.C., Granado, E., Huang, Q., Lynn, J.W.,

Campoy, J.C.P., Gopalakrishnan, J., Ramesha, K., “Incipient

Orbital Order in Half-Metallic Ba2FeReO6,” Phys. Rev. Lett.

98 (1), 017204 (2007).

Balogh, M.P., Jones, C.Y., Herbst, J.F., Hector Jr., L.G., Kundrat, M.,

“Crystal Structures and Phase Transformation of Deuterated

Lithium Imide, Li2ND,” J. Alloys Compd. 420 (1-2), 326

(2006).

Basu, S., Satija, S.K., “In-Situ X-Ray Reflectivity Study of Alkane

Films Grown From the Vapor Phase,” Langmuir 23 (16), 8331

(2007).

Bauer, B.J., Becker, M.L., Bajpai, V., Fagan, J.A., Hobbie, E.K.,

Migler, K., Guttman, C.M., Blair, W.R., “Measurement

of Single-Wall Nanotube Dispersion by Size Exclusion

Chromatography,” J. Phys. Chem. C, in press.

Bauer, E.D., Christianson, A.D., Gardner, J.S., Sidorov, V.A.,

Thompson, J.D., Sarrao, J.L., Hundley, M.F., “Physical

Properties of the Ferromagnetic Heavy-Fermion Compound

UIr2Zn20,” Phys. Rev. B 74 (15), 155118 (2006).

Becker, D.A., “Reflections on 35 Years of Biological SRM Production

and Analyses,” J. Radioanal. Nucl. Chem. 269 (2), 365 (2006).

Beekman, M., Kaduk, J.A., Huang, Q., Wong-Ng, W., Yang, Z.,

Wang, D., Nolas, G.S., “Synthesis and Crystal Structure of

Na1-xGe3+z: A Novel Zeolite-Like Framework Phase in the NaGe System,” Chem. Commun. 38 (22), 837 (2007).

Belik, A.A., Tsujii, N., Huang, Q., Takayama-Muromachi,

E., Takano, M., “Re-Entrant Spin-Glass Behaviour of

Geometrically Frustrated SrFe3(PO4)3O,” J. Phys.: Condens.

Matter 19 (14), 145221 (2007).

Benz, R.W., Nanda, H., Castro-Román, F., White, S.H., Tobias,

D.J., “Diffraction-Based Density Restraints for Membrane

and Membrane-Peptide Molecular Dynamics Simulations,”

Biophys. J. 91 (10), 3617 (2006).

Bhat, M.H., Peral, I., Copley, J.R.D., Angell, C.A., “The Boson

Peak in Melt-Formed and Damage-Formed Glasses: A Defect

Signature?” J. Non-Cryst. Solids 352 (42-49), 4517 (2006).

(chrns)

Bhatia, S., McCrickard, D.S., Lilley, T., North, C., Kienzle, P.,

“Scientists in the MIST: Simplifying Interface Design for End

Users,” Proceedings of World Conference on Educational

Multimedia, Hypermedia and Telecommunications

(EDMEDIA) 2006 (AAEC, June 2006, Chesapeake, VA) 2006

(1), 653 (2006).

Blackman, M.J., Bishop, R.L., “The Smithsonian-NIST Partnership:

the Application of Instrumental Neutron Activation Analysis to

Archaeology,” Archaeometry 49 (2), 321 (2007).

Borchers, J.A., “Preface: Proceedings of the 10th Joint MMMIntermag Conference, 7-11 January 2007, Baltimore,

Maryland,” J. Appl. Phys. 101 (9), 09A101 (2007).

Borchers, J.A., “Tenth Joint MMM-Intermag Conference 2007:

Conference Chair’s Forward,” IEEE Trans. Mag. 43 (6), 2082

(2007).

Bordallo, H.N., Aldridge, L.P., Desmedt, A., “Water Dynamics in

Hardened Ordinary Portland Cement Paste or Concrete:

From Quasielastic Neutron Scattering,” J. Phys. Chem. B 110

(36), 17966 (2006). (chrns)

Boukari, H., Sackett, D.L., Schuck, P., Nossal, R.J., “Single-Walled

Tubulin Ring Polymers,” Biopolym. 86 (5-6), 424 (2007).

(chrns)

Bowman Jr., R.C., Adolphi, N.L., Hwang, S.-J., Kulleck, J.G., Udovic,

T.J., Huang, Q., Wu, H., “Deuterium Site Occupancy and

Phase Boundaries in ZrNiDx (0.87≤x≤3.0),” Phys. Rev. B 74

(18), 184109 (2006).

64

î
Bowman Jr., R.C., Udovic, T.J., Jensen, C.M., “Preface,” J. Alloys

Compd., in press.

Boyce, D.E., Dawson, P.R., Sidle, B., Gnäupel-Herold, T., “A

Multiscale Methodology for Deformation Modeling Applied

to Friction Stir Welded Steel,” Comp. Mater. Sci. 38 (1), 158

(2006).

Brown, C.M., Jacques, T.J., Hess, N.J., Daemen, L.L., Mamontov, E.,

Linehan, J.C., Stowe, A.C., Autrey, T., “Dynamics of Ammonia

Borane Using Neutron Scattering,” Physica

B 385-386 (1), 266 (2006). (chrns)

Brown, C.M., Liu, Y., Tung, S.-P., Chen, W.-R., Hwang, B.-J.,

“Dynamics of Water in a Porous Phosphate Glass,” QuasiElastic Neutron Scattering Conference 2006 (QENS 2006),

edited by Sokol, P.E., Kaiser, H., Baxter, D., Pynn, R., Bossev,

D., Leuschner, M., (Mater. Res. Soc., June 2006, Bloomington,

IN) 45 (2007). (chrns)

Brown, M.D., Law, B.M., Satija, S., Hamilton, W.A., Watkins, E.,

Cho, J.-H.J., Majewski, J., “Comparison of Critical Adsorption

Scaling Functions Obtained From Neutron Reflectometry and

Ellipsometry,” J. Chem. Phys. 126 (20), 204704 (2007).

Burford, R.P., Markotsis, M.G., Knott, R.B., “Real-Time SANS Study

of Interpenetrating Polymer Network (IPN) Formation,”

Physica B 385-386 (1), 766 (2006).

Busch, S., Doster, W., Longeville, S., García Sakai, V., Unruh, T.,

“Microscopic Protein Diffusion at High Concentration,” QuasiElastic Neutron Scattering Conference 2006 (QENS 2006),

edited by Sokol, P.E., Kaiser, H., Baxter, D., Pynn, R., Bossev,

D., Leuschner, M., (Mater. Res. Soc., June 2006, Bloomington,

IN) 107 (2007). (chrns)

Butler, P., Dura, J., “Summer School on SANS and Reflectometry

Held at NIST,” Neutron News 18 (2), 3 (2007).

Caciuffo, R., Guidi, T., Amoretti, G., Carretta, S., Magnani, N.,

Santini, P., Mondelli, C., “Spin Dynamics of Molecular

Nanomagnets,” Physica B 385-386 (1), 301 (2006). (chrns)

Cappelletti, R.L., editor, “2006 NIST Center for Neutron Research

Accomplishments and Opportunities,” NIST SP 1060 (2006).

Cappelletti, R.L., Udovic, T.J., Chowdhuri, Z., Hauback, B.C.,

Maeland, A.J., Dimeo, R.M., “Diffusive Hydrogen Motion in

ZrBe2H0.56: A Quasielastic Neutron Scattering Study,” Physica B

385-386 (1), 208 (2006). (chrns)

Carretta, S., Santini, P., Amoretti, G., Guidi, T., Copley, J.R.D.,

Qiu, Y., Caciuffo, R., Timco, G., Winpenny, R.E.P.,

“Quantum Oscillations of the Total Spin in a Heterometallic

Antiferromagnetic Ring: Evidence from Neutron

Spectroscopy,” Phys. Rev. Lett. 98 (16), 167401 (2007). (chrns)

Celestian, A.J., Parise, J.B., Smith, R.I., Toby, B.H., Clearfield, A.,

“Role of the Hydroxyl–Water Hydrogen-Bond Network in

Structural Transactions and Selectivity Toward Cesium in

Cs0.38(D1.08H0.54)SiTi2O7 (D0.86H0.14)2O Crystalline

Silicotitanate,” Inorg. Chem. 46 (4), 1081 (2007).

Çetiner, S.M., Ünlü, K., Downing, R.G., “Development of Time-ofFlight Neutron Depth Profiling at Penn State University,” J.

Radioanal. Nucl. Chem. 271 (2), 275 (2007).

Chan, T.S., Liu, R.S., Yang, C.C., Li, W.-H., Lien, Y.H., Huang,

C.Y., Lynn, J.W., “Neutron Diffraction Study of Multiferroic

Tb0.85Na0.15MnO3-y,” J. Magn. Magn. Mater. 310 (2), 1151

(2007).

.

Chan, T.S., Liu, R.S., Yang, C.C., Li, W.-H., Lien, Y.H., Huang, C.Y.,

Lynn, J.W., Chen, J.M., Sheu, H.-S., “Influence of Oxygen

Defects on the Crystal Structure and Magnetic Properties of

the (Tb1-xNax)MnO3-y (0 ≤ x ≤ 0.3) System,” Inorg. Chem. 46

(11), 4575 (2007).

Chang, L.J., Terashita, H., Schweika, W., Chen, Y.Y., Gardner, J.S.,

“HoTbTi2O7, the Mixtures of Spin Ice and Spin Liquid,” J.

Magn. Magn. Mater. 310 (2), 1293 (2007).

Chatterjee, T., Krishnamoorti, R., “Dynamic Consequences of

the Fractal Network of Nanotube-Poly(Ethylene Oxide)

Nanocomposites,” Phys. Rev. E 75 (5), 050403 (2007). (chrns)

Chen, C., Maranas, J.K., García-Sakai, V., “Local Dynamics of

Syndiotactic Poly(Methyl Methacrylate) Using Molecular

Dynamics Simulation,” Macromol. 39 (26), 9630 (2006).

(chrns)

Chen, S.-H., Broccio, M., Liu, Y., Fratini, E., Baglioni, P., “The TwoYukawa Model and its Applications: the Cases of Charged

Proteins and Copolymer Micellar Solutions,” J. Appl. Cryst. 40

(s1), s321 (2007).

Chen, S.-H., Liu, L., Chu, X., Zhang, Y., Fratini, E., Baglioni, P.,

Faraone, A., Mamontov, E., “Experimental Evidence of Fragileto-Strong Dynamic Crossover in DNA Hydration Water,” J.

Chem. Phys. 125 (17), 171103 (2006). (chrns)

Chen, S.-H., Liu, L., Faraone, A., “Reply to Comment on ‘Pressure

Dependence of Fragile-to-Strong Liquid Transition and a

Possible Second Critical Point in Supercooled Confined

Water’ [Phys. Rev. Lett. 95 (11), 117802 (2005)],” Phys. Rev.

Lett. 97 (18), 189803 (2006). (chrns)

Chen, S.-H., Mallamace, F., Mou, C.-Y., Broccio, M., Corsaro, C.,

Faraone, A., Liu, L., “The Violation of the Stokes-Einstein

Relation in Supercooled Water,” Proceedings of the National

Academy of Sciences, edited by Stanley, H.E., (August 2006)

103 (35), 12974 (2006). (chrns)

Chen, W.C., Armstrong, G., Chen, Y., Collett, B., Erwin, R., Gentile,

T.R., Jones, G.L., Lynn, J.W., McKenny, S., Steinberg, J.E., “3He

Spin Filters for a Thermal Neutron Triple Axis Spectrometer,”

Physica B 397 (1-2), 168 (2007).

Chen, W.C., Borchers, J.A., Erwin, R., Gentile, T.R., Lynn, J.W.,

“News From NIST Center for Neutron Research: Polarized 3He Neutron Spin Filters for NCNR Instruments,” Notiz. Neut.

Luce Sincr. 12 (2), 32 (2007).

Chen, W.C., Gentile, T.R., Walker, T.G., Babcock, E., “SpinExchange Optical Pumping of 3He with Rb-K Mixtures and

Pure K,” Phys. Rev. A 75 (1), 013416 (2007).

Chen, W.-R., Porcar, L., Liu, Y., Butler, P.D., Magid, L.J., “Small

Angle Neutron Scattering Studies of the Counterion Effects

on the Molecular Conformation and Structure of Charged G4

PAMAM Dendrimers in Aqueous Solutions,” Macromol. 40

(16), 5887 (2007). (chrns)

Chen, Y., Stone, M.B., Kenzelmann, M., Batista, C.D., Reich, D.H.,

Broholm, C., “Phase Diagram and Spin Hamiltonian of

Weakly-Coupled Anisotropic S=1⁄2 Chains in

CuCl2 2((CD3)2SO),” Phys. Rev. B 75 (21), 214409 (2007

(chrns)

Chen, Y.-S., Peng, H., Hussey, D.S., Jacobson, D.L., Tran,

D.T., Abdel-Baset, T., Biernacki, M., “Water Distribution

Measurement for a PEMFC Through Neutron Radiography,” J.

Power Sources 170 (2), 376 (2007).

NCNR 2007 ACCOMPLISHMENTS AND OPPORTUNITIES

65

.
Cheng, G., Melnichenko, Y.B., Wignall, G.D., Hua, F., Hong,

K., Mays, J.W., “Conformation of Oligo(Ethylene Glycol)

Grafted Polystyrene in Dilute Aqueous Solutions,” Polym.

48 (14), 4108 (2007). (chrns)

Chi, S., Ye, F., Dai, P., Fernandez-Baca, J.A., Huang, Q., Lynn,

J.W., Plummer, E.W., Mathieu, R., Kaneko, Y., Tokura, Y.,

“Effect of Antiferromagnetic Spin Correlations on Lattice

Distortion and Charge Ordering in Pr0.5Ca1.5MnO4,”

Proceedings of the National Academy of Sciences, edited

by Stanley, H.E., (June 2007) 104 (26), 10796 (2007).

Chin, J., Forster, A., Clerici, C., Sung, L., Oudina, M., Rice, K.,

“Temperature and Humidity Aging of Poly(p-Phenylene2,6-Benzobisoxazole) Fibers: Chemical and Physical

Characterization,” Polym. Degrad. Stab. 92 (7), 1234

(2007). (chrns)

Choi, H.D., Firestone, R.B., Lindstrom, R.M., Molnár, G.L.,

Mughabghab, S.F., Paviotti-Corcuera, R., Révay, Z., Trkov,

A., Zhou, C.M., Zerkin, V., “Database of Prompt Gamma

Rays from Slow Neutron Capture for Elemental Analysis,”

International Atomic Energy Agency, (2006, Vienna,

Austria) IAEA Scientific and Technical Information

Publication 1263 (2007).

Choi, W.B., Li, L., Luzin, V., Neiser, R., Gnäupel-Herold, T.,

Prask, H.J., Sampath, S., Gouldstone, A., “Integrated

Characterization of Cold Sprayed Aluminum Coatings,”

Acta Mater. 55 (3), 857 (2007).

Christianson, A.D., Gardner, J.S., Kang, H.J., Chung, J.-H.,

Bobev, S., Sarrao, J.L., Lawrence, J.M., “Low Temperature

Behavior of the Heavy Fermion Ce3Co4Sn­13,” J. Mag

Magn. Mater. 310 (2), 266 (2007). (chrns)

Christopher, S.J., Pugh, R.S., Ellisor, M.B., Mackey, E.A., Spatz,

R.O., Porter, B.J., Bealer, K.J., Kucklick, J.R., Rowles, T.K.,

Becker, P.R., “Description and Results of the NIST/NOAA

2005 Interlaboratory Comparison Exercise for Trace

Elements in Marine Mammals,” Accred. Qual. Assur. 12

(3-4), 175 (2007).

Chu, X.-Q., Kolesnikov, A.I., Moravsky, A.P., García Sakai, V.,

Chen, S.-H., “Observation of a Dynamic Crossover in

Water Confined in Double-Wall Carbon Nanotubes,”

Phys. Rev. E, in press. (chrns)

Chung, M.K., Huang, P.J., Li, W.-H., Yang, C.C., Chan, T.S.,

Liu, R.S., Wu, S.Y., Lynn, J.W., “Crystalline and Magnetic

Structures of Sr2FeMoO6 Double Perovskites,” Physica B

385-386 (1), 418 (2006).

Chupp, T.E., Coulter, K.P., Kandes, M., Sharma, M., Smith,

T.B., Jones, G., Chen, W.C., Gentile, T.R., Rich, D.R.,

Lauss, B., Gericke, M.T., Gillis, R.C., Page, S.A., Bowman,

J.D., Penttila, S.I., Wilburn, W.S., Dabaghyan, M.,

Hersman, F.W., Mason, M., “A Large Area Polarized 3He

Neutron Spin Filter,” Nucl. Instrum. Methods Phys. Res.,

Sect. A 574 (3), 500 (2007).

Ciezak, J.A., Leão, J.B., Hudson, B.S., “Vibrational Analysis of

the Inelastic Neutron Ascattering Spectra of Electron

Donor-Acceptor Complexes. II. TetracyanoethylenePerylene by Electronic Structure Calculations,” J. Mol.

Struct. 767 (1-3), 23 (2006).

Clayton, D.A., Lacy, J.L., Downing, R.G., “Quality Assurance in Neutron

Detector Development by Neutron Depth Profiling,” Recent

Developments in Metrological and Quality Assurance Aspects of

Nuclear Analytical Methods, Proceedings of the American Nuclear

Society 2006 Winter Meeting, edited by Yoelin, C.A., Leutschuh,

E.M., (November 2006, Albuquerque, NM) 95, 397 (2006).

Colla, E.V., Weissman, M.B., Gehring, P.M., Xu, G., Luo, H.,

Gemeiner, P., Dkhil, B., “Nonferroelectric Aging in the Relaxor

PbMg1/3Nb2/3O3,” Phys. Rev. B 75 (2), 024103 (2007).

Comoletti, D., Grishaev, A., Whitten, A.E., Tsigelny, I., Taylor, P.,

Trewhella, J., “Synaptic Arrangement of the Neuroligin/βNeurexin Complex Revealed by X-Ray and Neutron Scattering,”

Struct. 15 (6), 693 (2007). (chrns)

Connolly, J., Bertram, W., Barker, J., Buckley, C., Edwards, T., Knott,

R., “Comparison of the Structure on the Nanoscale of Natural

Oil-Bearing and Synthetic Rock,” J. Petrol. Sci. Eng. 53 (3-4), 171

(2006). (chrns)

Copley, J.R.D., “Scientific Review: Total Neutron Scattering Cross

Sections,” Neutron News 18 (1), 30 (2007).

Craig, N., Speakman, R.J., Popelka-Filcoff, R.S., Glascock, M.D.,

Robertson, J.D., Shackley, M.S., Aldenderfer, M.S., “Comparison

of XRF and PXRF for Analysis of Archaeological Obsidian From

Southern Perú,” J. Archaeol. Sci., in press.

Cremer, J.T., Piestrup, M.A., Gary, C.K., Park, H., Pantell, R.H.,

“Biological Imaging with a Neutron Microscope,” Penetrating

Radiation Systems and Applications VI, edited by Doty, F.P.,

Schirato, R.C., Barber, H.B., Roehrig, H., (SPIE Conf. Proc.,

August 2004, Denver, CO) 5541, 75 (2004).

Crowson, D.A., Farkas, D., Corcoran, S.G., “Geometric Relaxation of

Nanoporous Metals: the Role of Surface Relaxation,” Scripta

Mater. 56 (11), 919 (2007).

Cunningham, W.C., “Study of Cryogenic Procedures for Preparation of

Food for Element Analysis,” J. Food Compos. Anal., in press.

Curtis, J.E., Dirama, T.E., Carri, G.A., Tobias, D.J., “Inertial Suppression

of Protein Dynamics in a Binary Glycerol-Trehalose Glass,” J. Phys.

Chem B. 110 (46), 22953 (2006).

Danoff, E.J., Wang, X., Tung, S.-H., Sinkov, N.A., Kemme, A.M.,

Raghavan, S.R., English, D.S., “Surfactant Vesicles for HighEfficiency Capture and Separation of Charged Organic Solutes,”

Langmuir, in press.

Das, S.K., Heinrich, F., Butz, T., “The Nuclear Quadrupole Interaction

at Inequivalent Lattice Sites in Ammonium Paramolybdate: A

TDPAC Study,” Chem. Phys. 327 (2-3), 291 (2006).

Datta, S.A.K., Curtis, J.E., Ratcliff, W., Clark, P.K., Crist, R.M., Lebowitz,

J., Krueger, S., Rein, A., “Conformation of the HIV-1 Gag Protein

in Solution,” J. Mol. Biol. 365 (3), 812 (2007). (chrns)

Dave, H., Gao, F., Schultz, M., Co, C.C., “Phase Behavior and SANS

Investigations of Edible Sugar-Limonene Microemulsions,”

Colloids Surf., B. 296 (1-3), 45 (2007). (chrns)

Davis, W.C., Christopher, S.J., Pugh, R.S., Donard, O.F.X., Krupp, E.A.,

Point, D., Horvat, M., Gibicar, D., Kljakovic-Gaspic, Z., Porter,

B.J., Schantz, M.M., “Certification of Methylmercury Content in

Two Fresh-Frozen Reference Materials: SRM 1947 Lake Michigan

Fish Tissue and SRM 1974b Organics in Mussel Tissue (Mytilus

edulis),” Anal. Bioanal. Chem. 387 (7), 2335 (2007).

66
Dean, K.M., Cook, W.D., Lin, M.Y., “Small Angle Neutron Scattering

and Dynamic Mechanical Thermal Analysis of Dimethacrylate/

Epoxy IPNs,” Eur. Polym. J. 42 (10), 2872 (2006).

Dee, D., Pencer, J., Nieh, M.-P., Krueger, S., Katsaras, J., Yada, R.Y.,

“Comparison of Solution Structures and Stabilities of Native,

Partially Unfolded and Partially Refolded Pepsin,” Biochem.

45 (47), 13982 (2006). (chrns)

dela Cruz, C.R., Lorenz, B., Ratcliff, W., Lynn, J., Gospodinov,

M.M., Chu, C.W., “The Pressure Effect on the Magnetic

Commensurability and Ferroelectricity in Multiferroic HoMn2O5,”

Physica B, in press.

DeSanto Jr., P., Buttrey, D.J., Grasselli, R.K., Pyrz, W.D., Lugmair, C.G.,

Volpe Jr., A.F., Vogt, T., Toby, B.H., “Comparison of MoVTaTeO

and MoVNbTeO M1 Crystal Chemistry,” Top. Catal. 38 (1-3), 31

(2006).

Diallo, S.O., Pearce, J.V., Azuah, R.T., Albergamo, F., Glyde, H.R.,

“Condensate Fraction and Atomic Kinetic Energy of Liquid 3He- 4He Mixtures,” Phys. Rev. B 74 (14), 144503 (2006).

Diallo, S.O., Pearce, J.V., Azuah, R.T., Kirichek, O., Taylor, J.W., Glyde,

H.R., “Bose-Einstein Condensation in Solid 4He,” Phys. Rev. Lett.

98 (20), 295301 (2007).

Diama, A., Simpson, M., Taub, H., Hansen, F.Y., Dimeo, R.M.,

Neumann, D.A., Herwig, K.W., Volkmann, U.G., “Studies of

Dynamical Layering in Adsorbed Organic Films,” Quasi-Elastic

Neutron Scattering Conference 2006 (QENS 2006), edited by

Sokol, P.E., Kaiser, H., Baxter, D., Pynn, R., Bossev, D., Leuschner,

M., (Mater. Res. Soc., June 2006, Bloomington, IN) 89 (2007).

(chrns)

Dimitrov, I.K., Daniilidis, N.D., Elbaum, C., Lynn, J.W., Ling, X.S., “Peak

Effect in Polycrystalline Vortex Matter,” Phys. Rev. Lett. 99 (4),

047001 (2007). (chrns)

Dinca, M., Dailly, A., Liu, Y., Brown, C.M., Neumann, D.A., Long, J.R.,

“Hydrogen Storage in a Microporous Metal-Organic Framework

with Exposed Mn2+ Coordination Sites,” J. Amer. Chem. Soc. 128

(51), 16876 (2006).

Dinca, M., Han, W.S., Liu, Y., Dailly, A., Brown, C.M., Long, J.R.,

“Observation of Cu2+-H2 Interactions in a Fully Desolvated

Sodalite-Type Metal-Organic Framework,” Angew. Chem. Int. Ed.

46 (9), 1419 (2007).

Downing, R.G., Çetiner, S., “Enhanced Reaction Rates in NDP Analysis

by Neutron Scattering” Nuclear Methods in Support of Nano- to

Micro-Domain Sciences,” Proceedings of the American Nuclear

Society 2006 Winter Meeting, edited by Yoelin, C.A., Leutschuh,

E.M., (November 2006, Albuquerque, NM) 95, 459 (2006).

Doxastakis, M., García Sakai, V., Ohtake, S., Maranas, J.K., de Pablo,

J.J., “A Molecular View of Melting in Anhydrous Phospholipidic

Membranes,” Biophys. J. 92 (1), 147 (2007). (chrns)

Durgun, E., Ciraci, S., Zhou, W., Yildirim, T., “Transition-Metal-Ethylene

Complexes as High-Capacity Hydrogen-Storage Media,” Phys. Rev.

Lett. 97 (22), 226102 (2006).

Durkee, D.A., Gomez, E.D., Ellsworth, M.W., Bell, A.T., Balsara, N.P.,

“Microstructure and Solvent Distribution in Cross-Linked Diblock

Copolymer Gels,” Macromol. 40 (14), 5103 (2007).

Dyck, M., Kerth, A., Blume, A., Lösche, M., “Interaction of the

Neurotransmitter, Neuropeptide Y, with Phospholipid Membranes:

Infrared Spectroscopic Characterization at the Air/Water

Interface,” J. Phys. Chem. B 110 (44), 22152 (2006).

Dyck, M., Lösche, M., “Interaction of the Neurotransmitter,

Neuropeptide Y, with Phospholipid Membranes: Film

Balance and Fluorescence Microscopy Studies,” J. Phys.

Chem. B 110 (44), 22143 (2006).

Egres, R.G., Nettesheim, F., Wagner, N.J., “Rheo-SANS

Investigation of Acicular-Precipitated Calcium

Carbonate Colloidal Suspensions Through the Shear

Thickening Transition,” J. Rheol. 50 (5), 685 (2006).

Eitouni, H.B., Balsara, N.P., “Electrochemically Controlled

Self-Assembly of an Organometallic Block Copolymer,”

J. Amer. Chem. Soc. 128 (50), 16248 (2006).

Enevoldsen, A.D., Hansen, F.Y., Diama, A, Taub, H., Dimeo,

R.M., Neumann, D.A., Copley, J.R.D., “Comparative

Study of Study of Normal and Branched Alkane

Monolayer Films Adsorbed on a Solid Surface. II.

Dynamics,” J. Chem. Phys. 126 (10), 104704 (2007).

(chrns)

Fagan, J.A., Landi, B.J., Mandelbaum, I., Simpson, J.R.,

Bajpai, V., Bauer, B.J., Migler, K., Hight Walker, A.R.,

Raffaelle, R., Hobbie, E.K., “Comparative Measures

of Single-Wall Carbon Nanotube Dispersion,” J. Phys.

Chem. B. 110 (47), 23801 (2006).

Fagan, J.A., Simpson, J.R., Landi, B.J., Richter, L.J.,

Mandelbaum, I., Bajpai, V., Ho, D.L., Raffaelle, R.,

Hight Walker, A.R., Bauer, B.J., Hobbie, E.K., “Dielectric

Response of Aligned Semiconducting Single-Wall

Nanotubes,” Phys. Rev. Lett. 98 (14), 147402 (2007).

Farrell, D.F., Ijiri, Y., Kelly, C.V., Borchers, J.A., Rhyne,

J.J., Ding, Y., Majetich, S.A., “Small Angle Neutron

Scattering Study of Disordered and Crystalline Iron

Nanoparticle Assemblies,” J. Magn. Magn. Mater. 303

(2), 318 (2006).

Fisher, B.M., Brune, C.R., Karwowski, H.J., Leonard, D.S.,

Ludwig, E.J., Black, T.C., Viviani, M., Kievsky, A., Rosati,

S., “Proton-3He Elastic Scattering at Low Energies,”

Phys. Rev. C 74 (3), 034001 (2006).

Foecke, T., Gnaeupel-Herold, T., “Robustness of the Sheet

Metal Springback Cup Test,” Met. Mat. Trans. A. 37A,

3503 (2006).

Foo, M.L., He, T., Huang, Q., Zandbergen, H.W., Siegrist,

T., Lawes, G., Ramirez, A.P., Cava, R.J., “Synthesis and

Characterization of the Pseudo-Hexagonal Hollandites

ALi2Ru6O12 (A = Na, K),” J. Solid State Chem. 179 (3),

941 (2006).

Foster, L.J.R., Knott, R., Sanguanchaipaiwong, V., Holden,

P.J., “Polyhydroxyalkanoate-Based Natural-Synthetic

Hybrid Copolymer Films: A Small-Angle Neutron

Scattering Study,” Physica B 385-386 (1), 770 (2006).

(chrns)

Francis, T.J., Vogt, B.D., Wang, M.X., Watkins, J.J., “Scaling

of Interdomain Spacing of Diblock Copolymers in a

Selective Diluent,” Macromol. 40 (7), 2515 (2007).

Fratini, E., Ridi, F., Chen, S.-H., Baglioni, P., “Hydration

Water and Microstructure in Calcium Silicate and

Aluminum Hydrates,” J. Phys.: Condens. Matter 18 (36),

S2467 (2006). (chrns)

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NCNR 2007 ACCOMPLISHMENTS AND OPPORTUNITIES

67
Ganeva, D.E., Sprong, E., de Bruyn, H., Warr, G.G., Such, C.H.,

Hawkett, B.S., “Particle Formation in Ab Initio RAFT

Mediated Emulsion Polymerization Systems,” Macromol.,

in press.

Gao, J., Yang, Y., Lee, D., Holdcroft, S., Frisken, B.J., “SelfAssembly of Latex Particles into Proton-Conductive

Membranes,” Macromol. 39 (23), 8060 (2006).

García Sakai, V., Mamontov, E., Lynn, J.W., Viciu, L., Cava,

R.J., “Dynamics of Water in the Na0.3CoO2·1.4H2O

Superconductor,” Phys. Rev. B 75 (1), 014505 (2007).

(chrns)

Garlea, V.O., Zheludev, A., Masuda, T., Manaka, H., Regnault,

L.-P., Ressouche, E., Grenier, B., Chung, J.-H., Qiu, Y.,

Habicht, K., Kiefer, K., Boehm, M., “Excitations From a

Bose-Einstein Condensate of Magnons in Coupled Spin

Ladders,” Phys. Rev. Lett. 98 (16), 167202 (2007). (chrns)

Garvey, C.J., Knott, R.B., Searson, M., Conroy, J.P., “USANS

Study of Wood Structure,” Physica B 385-386 (2), 877

(2006). (chrns)

Gavrin, V.N., Abdurashitov, J.N., Barsanov, V.I., Bowles, T.J.,

Cleveland, B.T., Elliott, S.R., Girin, S.V., Gorbachev, V.V.,

Gurkina, P.P., Haxton, W.C., Ibragimova, T.V., Janelidze,

A.A., Kalikhov, A.V., Karpenko, A.I., Khairnasov,

N.G., Khomyakov, Y.S., Knodel, T.V., Korenkova, A.V.,

Kotelnikov, N.A., Lande, K., Maltsev, V.V., Markov, S.Y.,

Matveev, V.A., Mirmov, I.N., Mishin, O.V., Nico, J.S.,

Oshkanov, N.N., Poplavsky, V.M., Petrov, A.N., Popov,

V.V., Selin, V.V., Shakirov, Z.N., Shikhin, A.A., Suzuki, A.,

Teasdale, W.A., Tuchkov, A.M., Vasiliev, B.A., Veretenkin,

E.P., Vermul, V.M., Voronov, S.A., Wilkerson, J.F., Yants,

V.E., Zamyatina, A.A., Zatsepin, G.T., Zlokazov, S.B.,

“Measurement of the Response of a Ga Solar Neutrino

Experiment to Neutrinos From an 37Ar Source,” Phys.

Atom. Nucl. 69 (11), 1820 (2006).

Gawrisch, K., Gaede, H.C., Mihailescu, M., White, S.H.,

“Hydration of POPC Bilayers Studied by 1H-PFG-MASNOESY and Neutron Diffraction,” Eur. Biophys. J. 36

(4-5), 281 (2007).

Gentile, T.R., Dewey, M.S., Mumm, H.P., Nico, J.S., Thompson,

A.K., Chupp, T.E., Cooper, R.L., Fisher, B.M., Kremsky,

I., Wietfeldt, F.E., Kiriluk, K.G., Beise, E.J., “Particle

and Photon Detection for a Neutron Radiative Decay

Experiment,” Nucl. Intrum. Methods Phys. Res., Sect. A,

in press.

George, M., Funkhouser, G.P., Terech, P., Weiss, R.G.,

“Organogels with Fe(III) Complexes of PhosphorusContaining Amphiphiles as Two-Component Isothermal

Gelators,” Langmuir 22 (18), 7885 (2006).

Gericke, M.T., Bowman, J.D., Carlini, R.D., Chupp, T.E.,

Coulter, K.P., Dabaghyan, M., Dawkins, M., Desai, D.,

Freedman, S.J., Gentile, T.R., Gillis, R.C., Greene, G.L.,

Hersman, F.W., Ino, T., Jones, G.L., Kandes, M., Lauss,

B., Leuschner, M., Lozowski, W.R., Mahurin, R., Mason,

M., Masuda, Y., Mitchell, G.S., Muto, S., Nann, H., Page,

S.A., Penttilä, S.I., Ramsay, W.D., Santra, S., Seo, P.-N.,

Sharapov, E.I., Smith, T.B., Snow, W.M., Wilburn, W.S.,

Yuan, V., Zhu, H., “Upper Bounds on Parity-Violating

γ-Ray Asymmetries in Compound Nuclei From Polarized

Cold Neutron Capture,” Phys. Rev. C 74 (6), 065503

(2006).

Gharib, A.G., Mohseni, S.G., Mohajer, M., Gharib, M., “Bioavailability

of Essential Trace Elements in the Presence of Phytate, Fiber and

Calcium,” J. Radioanal. Nucl. Chem. 270 (1), 209 (2006).

Gilliam, D.M., Maier-Komor, P., “Editorial,” Nucl. Instrum. Methods

Phys. Res., Sect. A 561 (1), vii (2006).

Glascock, M.D., Speakman, R.J., Popelka-Filcoff, R.S., editors,

Archaeological Chemistry: Analytical Techniques and

Archaeological Interpretation, (ACS Symp. Ser., March 2006,

Atlanta, GA) 968, (2007).

Gnäupel-Herold, T., Myneni, G.R., Ricker, R.E., “Investigations of

Residual Stresses and Mechanical Properties of Single Crystal

Niobium for SRF Cavities,” Single Crystal – Large Grain Niobium

Technology: International Niobium Workshop, edited by Myneni,

G.R., Carneiro, T., Hutton, A., (AIP, October 2006, Araxa, Brazil),

in press.

Gomez, E.D., Das, J., Chakraborty, A.K., Pople, J.A., Balsara, N.P.,

“Effect of Cross-Linking on the Structure and Thermodynamics of

Lamellar Block Copolymers,” Macromol. 39 (14), 4848 (2006).

Grilley, D., Misra, V., Caliskan, G., Draper, D.E., “Importance of Partially

Unfolded Conformations for Mg2+-Induced Folding of RNA

Tertiary Structure: Structural Models and Free Energies of Mg2+

Interactions,” Biochem., in press.

Grinberg, I., Suchomel, M.R., Dmowski, W., Mason, S.E., Wu, H.,

Davies, P.K., Rappe, A.M., “Structure and Polarization in the High

Tc Ferroelectric Bi(Zn, Ti)O3-PbTiO3 Solid Solutions,” Phys. Rev.

Lett. 98 (10), 107601 (2007).

Guidi, T., Copley, J.R.D., Qiu, Y., Carretta, S., Santini, P., Amoretti, G.,

Timco, G., Winpenny, R.E.P., Dennis, C.L., Caciuffo, R., “Spin

Dynamics of Fe7M (M=Zn,Mn) Heterometallic Rings Probed

by Neutron Spectroscopy,” Phys. Rev. B 75 (1), 014408 (2007).

(chrns)

Hamill, A.C., Wang, S.-C., Lee Jr., C.T., “Solution Structure of an

Amyloid-Forming Protein During Photoinitiated HexamerDodecamer Transitions Revealed Through Small-Angle Neutron

Scattering,” Biochem. 46 (26), 7694 (2007). (chrns)

Hamilton, W.A., Smith, G.S., Taylor, G.B., Larkins, B.M., Porcar, L.,

“Current and Future Capabilities of the Neutron Reflectometer

MIRROR at Oak Ridge National Laboratory’s High Flux Isotope

Reactor,” Physica B 385-386 (2), 1007 (2006).

Hammouda, B., “Solvation Characteristics of a Model Water-Soluble

Polymer,” J. Polym. Sci., Part B: Polym. Phys. 44 (22), 3195 (2006).

(chrns)

Hammouda, B., Ho, D.L., “Insight Into Chain Dimensions in PEO/

Water Solutions,” J. Polym. Sci., Part B: Polym. Phys., in press.

(chrns)

Hammouda, B., Mildner, D.F.R., “Small-Angle Neutron Scattering

Resolution with Refractive Optics,” J. Appl. Phys. 40 (2), 250

(2007). (chrns)

Hammouda, B., Worcester, D., “The Denaturation Transition of DNA in

Mixed Solvents,” Biophys. J. 91 (6), 2237 (2006). (chrns)

Han, X., Mihailescu, M., Hristova, K., “Neutron Diffraction Studies

of Fluid Bilayers with Transmembrane Proteins: Structural

Consequences of the Achondroplasia Mutation,” Biophys. J. 91

(10), 3736 (2006).

Hartman, M.R., Rush, J.J., Udovic, T.J., Bowman Jr., R.C., Hwang,

S.-J., “Structure and Vibrational Dynamics of Isotopically

Labeled Lithium Borohydride using Neutron Diffraction and

Spectroscopy,” J. Solid State Chem. 180 (4), 1298 (2007).

68
Hauet, T., Mangin, S., Montaigne, F., Borchers, J.A., Henry, Y., “Tuning

Exchange-Bias Properties by Thermal Effects in a Hard/Soft

Bilayer,” Appl. Phys. Lett. 91 (2), 022505 (2007).

He, C., Torija, M.A., Wu, J., Lynn, J.W., Zheng, H., Mitchell, J.F.,

Leighton, C., “Non-Griffiths-Like Clustered Phase Above the Curie

Temperature of the Doped Perovskite Cobaltite La1-xSrxCoO3,”

Phys. Rev. B 76 (1), 014401 (2007).

Healy, J., Edward, G.H., Knott, R.B., “Residual Orientation in Injection

Micro-Molded Samples,” Physica B 385-386 (1), 620 (2006).

Heimbach, C.R., “Cosmic Coincidences: Investigations for Neutron

Background Suppression,” J. Res. Natl. Inst. Stand. Technol. 112

(2), 95 (2007).

Heimbach, C.R., “The Neutron Spectrum of NBS-1,” J. ASTM Int. 3 (4),

JAI13474 (2006).

Heimbach, C., “NIST Calibration of a Neutron Spectrometer ROSPEC,”

J. Res. Natl. Inst. Stand. Technol. 111 (6), 419 (2006).

Heitfeld, K.A., Guo, T., Yang, G., Schaefer, D.W., “Temperature

Responsive Hydroxypropyl Cellulose for Encapsulation,” Mater.

Sci. Eng., C, in press. (chrns)

Helton, J.S., Matan, K., Shores, M.P., Nytko, E.A., Bartlett, B.M.,

Yoshida, Y., Takano, Y., Suslov, A., Qiu, Y., Chung, J.-H., Nocera,

D.G., Lee, Y.S., “Spin Dynamics of the Spin-1/2 Kagome Lattice

Antiferromagnet ZnCu3(OH)6Cl2,” Phys. Rev. Lett. 98 (10),

107204 (2007). (chrns)

Hiraka, H., Ohta, S., Wakimoto, S., Matsuda, M., Yamada, K.,

“Ni-Impurity Effects on Incommensurate Spin Correlations in the

Superconducting Phase of La2-xSrxCuO4 Near the Spin-Glass Phase

Boundary,” J. Phys. Soc. Jpn. 76 (7), 074703 (2007). (chrns)

Hjörvarsson, B., Andersson, G., Dura, J.A., Udovic, T.J., Isberg,

P., Majkrzak, C.F., “Temperature Dependence of the Magnetic

Interlayer Ordering in Fe(3)/V(14)Hx (001) Superlattices,”

Superlattices Microstruct., in press.

Holman, K.L., Huang, Q., Klimczuk, T., Trzebiatowski, K., Bos, J.W.G.,

Morosan, E., Lynn, J.W., Cava, R.J., “Synthesis and Properties of

the Double Perovskites La2NiVO6, La­2CoVO6, and La2CoTiO6

J. Solid State Chem. 180 (1), 75 (2007).

Hong, T., Kenzelmann, M., Turnbull, M.M., Landee, C.P., Lewis, B.D.,

Schmidt, K.P., Uhrig, G.S., Qiu, Y., Broholm, C., Reich,

D., “Neutron Scattering From a Coordination Polymer Quantum

Paramagnet,” Phys. Rev. B 74 (9), 094434 (2006). (chrns)

Horkay, F., Hecht, A.-M., Geissler, E., “Similarities Between

Polyelectrolyte Gels and Bipolymer Solutions,” J. Polym. Sci., Part

B: Polym. Phys. 44 (24), 3679 (2006). (chrns)

Horkay, F., Hecht, A.-M., Rochas, C., Basser, P.J., Geissler, E.,

“Anomalous Small Angle X-Ray Scattering Determination of Ion

Distribution Around a Polyelectrolyte Bipolymer in Salt Solution,”

J. Chem. Phys. 125 (23), 234904 (2006). (chrns)

Hu, R., Hudis, J., Stock, C., Broholm, C.L., Petrovic, C., “Single Crystal

Growth of YbRh­2­Si­2 Using Zn Flux,” J. Cryst. Growth 304 (1

(2007).

Huang, X., Raghavan, S.R., Terech, P., Weiss, R.G., “Distinct Kinetic

Pathways Generate Organogel Networks with Contrasting

Fractality and Thixotropic Properties,” J. Amer. Chem. Soc. 128

(47), 15341 (2007).

Hubbard Jr., F.P., Abbott, N.L., “Effect of Light on SelfAssembly of Aqueous Mixtures of Sodium Dodecyl

Sulfate and a Cationic, Bolaform Surfactant Containing

Azobenzene,” Langmuir 23 (9), 4819 (2007). (chrns)

Huffman, P.R., Arif, M., Black, T.C., Jacobson, D.L., Schoen,

K., Snow, W.M., Werner, S.A., “Precision Neutron

Interferometric Measurements of the n-p, n-d, and

n-3He Zero-Energy Coherent Neutron Scattering

Amplitudes,” Physica B 385-386 (2), 1365 (2006).

Hussey, D.S., Jacobson, D.L., Arif, M., Owejan, J.P., Gagliardo,

J.J., Trabold, T.A., “Neutron Images of the ThroughPlane Water Distribution of an Operating PEM Fuel

Cell,” J. Power Sources, in press.

Íñiguez, J., Yildirim, T., “Hydrogen-Related Catalytic Effects

of Ti and Other Light Transition Metals on NaAlH4

Surfaces,” J. Phys. Condens. Matter 19 (17), 176007

(2007).

Íñiguez, J., Zhou, W., Yildirim, T., “Vibrational Properties of

TiHn Complexes Adsorbed on Carbon Nanostructures,”

Chem. Phys. Lett., in press.

Jackson, A., White, J., “Small Angle Scattering From Protein/

Sugar Conjugates,” Physica B 385-386 (1), 818 (2006).

Jacquin, M., Muller, P., Talingting-Pabalan, R., Cottet, H.,

Berret, J.F., Futterer, T., Théodoly, O., “Chemical

Analysis and Aqueous Solution Properties of Charged

Amphiphilic Block Copolymers PBA-b-PAA Synthesized

by MADIX,” J. Colloid Interface Sci., in press. (chrns)

Jeng, U.-S., Lin, T.-L., Lin, J.M., Ho, D.L., “Contrast Variation

SANS for the Solution Structure of the β-Amyloid

Peptide 1-40 Influenced by SDS Surfactants,” Physica B

385-386 (2), 865 (2006).

Jennings, H.M., Thomas, J.J., Gevrenov, J.S., Constantinides,

G., Ulm, F.-J., “A Multi-Technique Investigation of the

Nanoporosity of Cement Paste,” Cem. Concr. Res. 37

(3), 329 (2007). (chrns)

Jennings, H.M., Thomas, J.J., Gevrenov, J.S., Constantinides,

G., Ulm, F.-J., “Relating the Nanostructure of Concrete

to Engineering Properties,” Proceedings of the 2nd

International Symposium on Nanotechnology in

Construction, edited by de Miguel, Y., Porro, A., Bartos,

P.J.M., (November 2005, Bilbao, Spain) 57 (2006).

(chrns)

Jiang, J., Burger, C., Li, C., Li, J., Lin, M.Y., Colby, R.H.,

Rafailovich, M.H., Sokolov, J.C., “Shear-Induced Layered

Structure of Polymeric Micelles by SANS,” Macromol.

40 (11), 4016 (2007). (chrns)

Jones, G.L., Dias, F., Collett, B., Chen, W.C., Gentile, T.R.,

Piccoli, P.M.B., Miller, M.E., Schultz, A.J., Yan, H., Tong,

X., Snow, W.M., Lee, W.T., Hoffman, C., Thomison, J.,

“Test of a Continuously Polarized 3He Neutron Spin

Filter with NMR-Based Polarization Inversion on a

Single-Crystal Diffractometer,” Physica B 385-386 (2),

1131 (2006).

NCNR 2007 ACCOMPLISHMENTS AND OPPORTUNITIES

69
Kaiser, H., Armstrong, N.L., Wietfeldt, F.E., Huber, M.,

Black, T.C., Arif, M., Jacobson, D.L., Werner, S.A.,

“Gravitationally Induced Quantum Interference Using a

Floating Interferometer Crystal,” Physica B 385-386 (2),

1384 (2006).

Kali, G., Georgiou, T.K., Iván, B., Patrickios, C.S., Loizou, E.,

Thomann, Y., Tiller, J.C., “Synthesis and Characterization

of Anionic Amphiphilic Model Conetworks Based on

Methacrylic Acid and Methyl Methacrylate: Effects of

Composition and Architecture,” Macromol. 40 (6), 2192

(2007).

Kang, H.J., Dai, P., Campbell, B.J., Chupas, P.J., Rosenkranz,

S., Lee, P.L., Huang, Q., Li, S., Komiya, S., Ando, Y.,

“Microscopic Annealing Process and its Impact on

Superconductivity in T′-Structure Electron-Doped

Copper Oxides,” Nature Mater. 6 (3), 224 (2007).

Kenzelmann, M., Lawes, G., Harris, A.B., Gasparovic, G.,

Broholm, C., Ramirez, A.P., Jorge, G.A., Jaime, M., Park,

S., Huang, Q., Sharpiro, A.Y., Demianets, L.A., “Direct

Transition From a Disordered to a Multiferroic Phase

on a Triangular Lattice,” Phys. Rev. Lett. 98 (26), 267205

(2007). (chrns) 

K ̧pa, H., Kolesnik, S., Wiren, Z., Leao, J., Brown, C.M.,

Dabrowski, B., Furdyna, J.K., Giebultowicz, T.M.,

“Inelastic Neutron Scattering From Antiferromagnetically

Coupled Nearest-Neighbor Spin Pairs in Zn(Mn)O and

Zn(Mn)Te,” Physica B 385-386 (1), 388 (2006). (chrns) 

K ̧pa, H., Majkrzak, C.F., Sipatov, A.Y., Giebultowicz, T.M.,

“Ferromagnetic Semiconductor Superlattices Studied by

Polarized Neutron Reflectometry,” Physica B 397 (1-2),

36 (2007).

K ̧pa, H., Majkrzak, C.F., Sipatov, A.Y., Wiren, Z.Q.,

Giebultowicz, T.M., “Neutron Reflectivity Investigations of

EuS/PbS Superlattices Grown on (1 1 1) BaF2 Substrate,”

J. Magn. Magn. Mater. 310 (2), 2280 (2007).

Ketner, A.M., Kumar, R., Davies, T.S., Elder, P.W., Raghavan,

S.R., “A Simple Class of Photorheological Fluids:

Surfactant Solutions with Viscosity Tunable by Light,” J.

Amer. Chem. Soc. 129 (6), 1553 (2007).

Kim, M.S., Bennett, M.C., Sokolov, D.A., Aronson, M.C.,

Millican, J.N., Chan, J.Y., Huang, Q., Chen, Y., Lynn, J.W.,

“Synthesis and Study of the Heavy-Fermion Compound

Yb5Pt9,” Phys. Rev. B 74 (22), 224431 (2006).

Kim, S., Cho, J., Char, K., “Thermally Stable Antireflective

Coatings Based on Nanoporous Organosilicate Thin

Films,” Langmuir 23 (12), 6737 (2007). (chrns)

Kim, T., Jung, Y., Kim, M., Arif, M., Jacobson, D.L., Hussey,

D., Sim, C., Lee, S., Jeon, J., “The Visualization of Water

Distribution at the PEMFC Using the Neutron Imaging

Technique: Feasibility Test,” 2005 IEEE Nuclear Science

Symposium Conference Record, (October 2005) 2, 639

(2005).

Kim, T.-H., Choi, S.-M., Kline, S.R., “SANS Studies of

Polymerized Nano-Particles Using Nonionic/Cationic

Surfactant Mixture,” Physica B 385-386 (1), 787 (2006).

Kim, T.-H., Doe, C., Kline, S.R., Choi, S.-M., “WaterRedispersible Isolated Single-Walled Carbon Nanotubes

Fabricated by In Situ Polymerization of Micelles,” Adv.

Mater. 19 (7), 929 (2007). (chrns)

King Jr., H.E., Milner, S.T., Lin, M.Y., Singh, J.P., Mason, T.G., “Structure

and Rheology of Organoclay Suspensions,” Phys. Rev. E 75 (2),

021403 (2007). (chrns)

Kintzel Jr., E.J., Herwig, K.W., Kidder, M.K., Britt, P.F., Buchanan III,

A.C., Chaffee, A.L., “A Quasi-Elastic Neutron Scattering Study

of the Dynamics of Alkane and Ether Molecules Tethered to the

Surface of MCM-41,” Quasi-Elastic Neutron Scattering Conference

2006 (QENS 2006), edited by Sokol, P.E., Kaiser, H., Baxter, D.,

Pynn, R., Bossev, D., Leuschner, M., (Mater. Res. Soc., June 2006,

Bloomington, IN) 31 (2007). (chrns)

Kirby, B.J., Borchers, J.A., Rhyne, J.J., O’Donovan, K.V., te Velthuis,

S.G.E., Roy, S., Sanchez-Hanke, C., Wojtowicz, T., Liu, X., Lim,

W.L., Dobrowolska, M., Furdyna, J.K., “Magnetic and Chemical

Nonuniformity in Ga1-xMnxAs Films as Probed by Polarized

Neutron and X-Ray Reflectometry,” Phys. Rev. B 74 (24),

245304 (2006).

Kirby, B.J., Fitzsimmons, M.R., Borchers, J.A., Ge, Z., Liu, X., Furdyna,

J.K., “Pinned Spin Depth Profile of an Oxidized-Mn/Ga1-xMnxAs

Exchange Bias Bilayer – The Effects of Overannealing,” IEEE

Trans. Mag. 43 (6), 3016 (2007).

Kitchens, C.L., Bossev, D.P., Roberts, C.B., “Solvent Effects on AOT

Reverse Micelles in Liquid and Compressed Alkanes Investigated

by Neutron Spin-Echo Spectroscopy,” J. Phys. Chem. B 110 (41),

20392 (2006). (chrns)

Kline, S.R., “Reduction and Analysis of SANS and USANS Data Using

IGOR Pro,” J. Appl. Cryst. 39 (6), 895 (2006). (chrns)

Klupp, G., Matus, P., Quintavalle, D., Kiss, L.F., Kováts, É., Nemes, N.M.,

Kamarás, K., Pekker, S., Jánossy, A., “Phase Segregation on the

Nanoscale in Na2C60,” Phys. Rev. B 74 (19), 195402 (2006). (chrns)

Knott, R.B., Lin, M., Hanley, H.J.M., Muir, D., “Preliminary SANS

Studies of the Structure of Nickel Powders on the Nanoscale,”

Physica B 385-386 (2), 908 (2006).

Koga, T., Jerome, J., Rafailovich, M.H., Chu, B., Douglas, J., Satija, S.,

“Supercritical Fluid Processing of Polymer Thin Films: An X-Ray

Study of Molecular-Level Porosity,” Adv. Colloid Interface Sci. 128-

130, 217 (2006).

Kopetka, P., Williams, R.E., Rowe, J.M., “NIST Liquid Hydrogen Cold

Source,” NISTIR 7352 (2006).

Kropka, J.M., Putz, K.W., Pryamitsyn, V., Ganesan, V., Green, P.F.,

“Origin of Dynamical Properties in PMMA-C60 Nanocomposites,”

Macromol. 40 (15), 5424 (2007). (chrns)

Kucerka, N., Pencer, J., Sachs, J.N., Nagle, J.F., Katsaras, J., “Curvature

Effect on the Structure of Phospholipid Bilayers,” Langmuir 23

(3), 1292 (2007).

Kucklick, J.R., Krahn, M.M., Becker, P.R., Porter, B.J., Schantz, M.M.,

York, G.S., O’Hara, T.M., Wise, S.A., “Persistent Organic Pollutants

in Alaskan Ringed Seal (Phoca hispida) and Walrus (Odobenus 

rosmarus) Blubber,” J. Environ. Monit. 8 (8), 848 (2006).

Kumar, R.S., Cornelius, A.L., Somayazulu, M., Errandonea, D., Nicol,

M.F., Gardner, J., “High Pressure Structure of Tb2Ti2O7 Pyrochlore

at Cryogenic Temperatures,” Phys. Stat. Sol. B 244 (1), 266 (2007).

Kuntz, D.M., Walker, L.M., “Solution Behavior of Rod-Like

Polyelectrolyte-Surfactant Aggregates Polymerized From Wormlike

Micelles,” J. Phys. Chem. B 111 (23), 6417 (2007). (chrns)

î

e

e

70

e
Kurzman, J.A., Geselbracht, M.J., “Probing Octahedral Tilting in DionJacobson Layered Perovskites with Neutron Powder Diffraction

and Raman Spectroscopy,” Solid-State Chemistry of Inorganic

Materials VI – Symposium QQ, edited by Seshadri, R., Kolis, J.W.,

Mitzi, D.B., Rosseinsky, M.J., (Mater. Res. Soc. Symp., Warrendale,

PA, November 2007) 988, QQ08-06 (2007).

Lauss, B., Bowman, J.D., Carlini, R.D., Chupp, T.E., Chen, W., Corvig,

S., Dabaghyan, M., Desai, D., Freedman, S.J., Gentile, T.R.,

Gericke, M.T., Gillis, R.C., Greene, G.L., Hersman, F.W., Ino,

T., Ito, T., Jones, G.L., Kandes, M., Leuschner, M., Lozowski, B.,

Mahurin, R., Mason, M., Masuda, Y., Mei, J., Mitchell, G.S., Muto,

S., Nann, H., Page, S.A., Penttila, S.I., Ramsay, W.D., Santra, S.,

Seo, P.-N., Sharapov, E.I., Smith, T.B., Snow, W.M., Wilburn, W.S.,

Yuan, V., Zhu, H., “Precision Measurement of Parity Violation

in Polarized Cold Neutron Capture on the Proton: The NPDγ

Experiment,” Seventeenth International Conference on Particles

and Nuclei, edited by Barnes, P.D., Cooper, M.D., Eisenstein, R.A.,

van Hecke, H., Stephenson, G.J., (AIP, October 2005, Santa Fe,

NM) 842, 790 (2006).

Lavery, K.A., Vogt, B.D., Prabhu, V.M., Lin, E.K., Wu, W.-L., Satija, S.K.,

Choi, K.-W., “Exposure Dose Effects on the Reaction-Diffusion

Process in Model Extreme Ultraviolet Photoresists,” J. Vac. Sci.

Technol., B 24 (6), 3044 (2006).

Law, M., Gnaëpel-Herold, T., Luzin, V., Bowie, G., “Neutron Residual

Stress Measurements in Linepipe,” Physica B 385-386 (2), 900

(2006).

Law, M., Prask, H., Luzin, V., Gnaeupel-Herold, T., “Residual Stress

Measurements in Coil, Linepipe and Girth Welded Pipe,” Mater.

Sci. Eng. A 437 (1), 60 (2006).

Lazzeri, P., Vanzetti, L., Anderle, M., Bersani, M., Park, J.J., Lin, Z.,

Briber, R.M., Rubloff, G.W., Kim, H.C., Miller, R.D., “Thin-Film

Transformations and Volatile Products in the Formation of

Nanoporous Low-k Polymethylsilsesquioxane-Based Dielectric,”

J. Vac. Sci. Technol., B 23 (3), 908 (2005).

Lee, D., Walsh, J.D., Migliorini, M., Yu, P., Cai, T., Schwieters, C.D.,

Krueger, S., Strickland, D.K., Wang, Y.-X., “The Structure of

Receptor-Associated Protein (RAP),” Protein Sci., in press.

Lee, D., Walsh, J.D., Yu, P., Markus, M.A., Choli-Papadopoulou, T.,

Schwieters, C.D., Krueger, S., Draper, D.E., Wang, Y.-X., “The

Structure of Free L11 and Functional Dynamics of L11 in Free,

L11-rRNA(58 nt) Binary and L11-rRNA(58 nt)-Thiostrepton

Ternary Complexes,” J Mol. Biol. 367 (4), 1007 (2007). (chrns)

Lee, H.-J., Soles, C.L., Liu, D.-W., Bauer, B.J., Lin, E.K., Wu, W.-L.,

Gallagher, M., “Structural Characteristics of Methylsilsesquioxane

Based Porous Low-k Thin Films Fabricated with Increasing CrossLinked Particle Porogen Loading,” J. Appl. Phys. 100 (6), 064104

(2006).

Lee, J.-H., Kim, H.-S., Pate, B.D., Choi, S.-M., “Effects of Side-Chain

Length on the Magnetic Response of Discotic Metallomesogens,”

J. Appl. Cryst. 40, s68 (2007). (chrns)

Lee, S.-H., Gasparovic, G., Broholm, C., Matsuda, M., Chung, J.-H., Kim,

Y.J., Ueda, H., Xu, G., Zschack, P., Kakurai, K., Takagi, H., Ratcliff,

W., Kim, T.H., Cheong, S.-W., “Crystal Distortions in Geometrically

Frustrated ACr2O4 (A = Zn, Cd),” J. Phys.: Condens. Matter 19

(14), 145259 (2007). (chrns)

Lee, S.-H., Kikuchi, H., Qiu, Y., Lake, B., Huang, Q., Habicht, K., Kiefer,

K., “Quantum Spin Liquid States in the Two Dimensional Kagomé

Antiferromagnets ZnxCu4-x(OD)6Cl2,” Nature Mater., in press.

(chrns)

Lee, W., Ni, S., Deng, J., Kim, B.-S., Satija, S.K., Mather, P.T.,

Esker, A.R., “Telechelic Poly(Ethylene Glycol)-POSS

Amphiphiles at the Air/Water Interface,” Macromol. 40

(3), 682 (2007).

Lee, Y.S., Wagner, N.J., “Rheological Properties and SmallAngle Neutron Scattering of a Shear Thickening,

Nanoparticle Dispersion at High Shear Rates,” Ind. Eng.

Chem. Res. 45 (21), 7015 (2006). (chrns)

Lenhart, J.L., Fischer, D., Sambasivan, S., Lin, E.K., Wu, W.-L.,

Guerrero, D.J., Wang, Y., Puligadda, R., “Understanding

Deviations in Lithographic Patterns Near Interfaces:

Characterization of Bottom Anti-Reflective Coatings

(BARC) and the BARC-Resist Interface,” Appl. Surf. Sci.

253 (9), 4166 (2007).

Levin, I., Stennett, M.C., Miles, G.C., Woodward, D.I., West,

A.R., Reaney, I.M., “Coupling Between Octahedral

Tilting and Ferroelectric Order in Tetragonal Tungsten

Bronze-Structured Dielectrics,” Appl. Phys. Lett. 89

(12), 122908 (2006).

Li, D., O’Connor, B.H., Low, I.-M., van Riessen, A., Toby,

B.H., “Mineralogy of Al-Substituted Goethites,” Powder

Diffr. 21 (4), 289 (2006).

Li, J., Jiang, J., Li, C., Lin, M.Y., Schwarz, S.A., Rafailovich,

M.H., Sokolov, J., “Effect of Temperature on ShearInduced Anisotropic Structure in Polymer Clay

Hydrogels,” Macromol. Rapid Comm. 27 (20), 1787

(2006). (chrns)

Li, Q., Gray, K.E., Zheng, H., Claus, H., Rosenkranz, S.,

Nyborg Ancona, S., Osborn, R., Mitchell, J.F., Chen,

Y., Lynn, J.W., “Reentrant Orbital Order and the True

Ground State of LaSr2 Mn­2O­7,” Phys. Rev. Lett. 98 (

167201 (2007).

Li, Y.-C., Chen, K.-B., Chen, H.-L., Hsu, C.-S., Tsao, C.-

S., Chen, J.-H., Chen, S.-A., “Fractal Aggregates of

Conjugated Polymer in Solution State,” Langmuir

22 (26), 11009 (2006).

Lindstrom, R.M., “Toolkits for Nuclear Science: Data and

Spreadsheets,” J. Radional. Nucl. Chem. 270 (2), 335

(2006).

Lindstrom, R.M., Zeisler, R., Greenberg, R.R., “Accuracy and

Uncertainty in Radioactivity Measurement for NAA,” J.

Radioanal. Nucl. Chem. 271 (2), 311 (2007).

Liu, D., Zhang, Y., Chen, C.-C., Mou, C.-Y., Poole, P.H., Chen,

S.-H., “Observation of the Density Minimum in Deeply

Supercooled Confined Water,” Proceedings of the

National Academy of Sciences, edited by Stanley, H.E.,

(June 2007) 104 (23), 9570 (2007). (chrns)

Liu, L., Chen, S.-H., Faraone, A., Yen, C.-W., Mou, C.-Y.,

Kolesnikov, A.I., Mamontov, E., Leao, J., “Quasielastic

and Inelastic Neutron Scattering Investigation of

Fragile-to-Strong Crossover in Deeply Supercooled

Water Confined in Nanoporous Silica Matrices.” J. Phys.:

Condens. Matter 18 (36), S2261 (2006). (chrns)

Liu, Y., Brown, C.M., Blackburn, J.L., Neumann, D.A.,

Gennett, T., Simpson, L., Parilla, P., Dillon, A.C., Heben,

M.J., “Inelastic Neutron Scattering of H2 Adsorbed on

Boron Substituted Single Walled Carbon Nanotubes,” J.

Alloys Compd., in press.

NCNR 2007 ACCOMPLISHMENTS AND OPPORTUNITIES

71
Liu, Y., Brown, C.M., Neumann, D.A., Peterson, V.K., Kepert,

C.J., “Inelastic Neutron Scattering of H2 Adsorbed in

HKUST-1,” J. Alloys Compd., in press.

Livingston, R.A., Nemes, N.M., Neumann, D.A., “States of

Water in Hydrated Cement Paste: Powers and Brownyard

Revisited,” 12th International Congress of the Chemistry

of Cement, edited by Beaudoin, J., (ICCC, July 2007,

Montréal, Canada) 00297 (2007).

Lodge, T.P., Taribagil, R., Yoshida, T., Hillmyer, M.A., “SANS

Evidence for the Cross-Linking of Wormlike Micelles by

a Model Hydrophobically Modified Polymer,” Macromol.

40 (13), 4728 (2007).

Loizou, E., Weisser, J.T., Dundigalla, A., Porcar, L., Schmidt,

G., Wilker, J.J., “Structural Effects of Crosslinking a

Biopolymer Hydrogel Derived From Marine Mussel

Adhesive Protein,” Macromol. Biosci. 6 (9), 711 (2006).

Lu, L., Hancock, J.N., Chabot-Couture, G., Ishii, K., Vajk, O.P.,

Yu, G., Mizuki, J., Casa, D., Gog, T., Greven, M., “Incident

Energy and Polarization-Dependent Resonant Inelastic

X-Ray Scattering Study of La2CuO4,” Phys. Rev. B 74 (22),

224509 (2006).

Ludlow, D.J., Calebrese, C.M., Yu, S.H., Dannehy, C.S.,

Jacobson, D.L., Hussey, D.S., Arif, M., Jensen, M.K.,

Eisman, G.A., “PEM Fuel Cell Membrane Hydration

Measurement by Neutron Imaging,” J. Power Sources 162

(1), 271 (2006).

Lufaso, M.W., Schulze, W.A., Misture, S.T., Vanderah, T.A.,

“Crystal Structure, Magnetic, and Dielectric Properties of

Aurivillius-Type Bi3Fe0.5Nb1.5O9,” J. Solid State Chem., in

press.

Lufaso, M.W., Vanderah, T.A., Pazos, I.M., Levin, I., Roth,

R.S., Nino, J.C., Provenzano, V., Schenck, P.K., “Phase

Formation, Crystal Chemistry, and Properties in the

System Bi2O3-Fe2O3-Nb2O5,” J. Solid State Chem. 179

(12), 3900 (2006).

Lumsden, M.D., Nagler, S.E., Sales, B.C., Tennant, D.A.,

McMorrow, D.F., Lee, S.-H., Park, S., “Magnetic Excitation

Spectrum of the Square Lattice S=1/2 Heisenberg

Antiferromagnet K2V3O8,” Phys. Rev. B 74 (21), 214424

(2006). (chrns)

Lynn, J.W., Argyriou, D.N., Ren, Y., Chen, Y., Mukovskii,

Y.M., Shulyatev, D.A., “Order and Dynamics of Intrinsic

Nanoscale Inhomogeneities in Manganites,” Phys. Rev. B

76 (1), 014437 (2007).

Lynn, J.W., Chen, Y., Huang, Q., Goh, S.K., Williams, G.V.M.,

“Search for Magnetic Order in Superconducting

RuSr2Eu1.2Ce0.8Cu2O10,” Phys. Rev. B 76 (1), 014519

(2007).

Ma, M., Chernova, N.A., Toby, B.H., Zavalij, P.Y., Whittingham,

M.S., “Structural and Electrochemical Behavior of

LiMn0.4Ni0.4Co0.2­O2,” J. Power Sources 165 (2), 5

(2007).

Mackey, E.A., Cronise, M.P., Fales, C.N., Greenberg, R.R.,

Leigh, S.D., Long, S.E., Marlow, A.F., Murphy, K.E., Oflaz,

R., Sieber, J.R., Rearick, M.S., Wood, L.J., Yu, L.L., Wilson,

S.A., Briggs, P.H., Brown, Z.A., Budahn, J., Kane, P.F., Hall

Jr., W.L., “Development and Certification of the New SRM

695 Trace Elements in Multi-Nutrient Fertilizer,” Anal.

Bioanal. Chem. 387 (7), 2401 (2007).

Majkrzak, C.F., Cappelletti, R., “American Conference on Neutron

Scattering Deemed a Success,” Neutron News 15 (4), 4 (2004).

Malardier-Jugroot, C., Head-Gordon, T., “Separable Cooperative

and Localized Translational Motions of Water Confined by a

Chemically Heterogeneous Environment,” Phys. Chem. Chem.

Phys. 9 (16), 1962 (2007). (chrns)

Mamontov, E., “Mobility of Water on Oxide Surfaces Studied by QENS,”

Quasi-Elastic Neutron Scattering Conference 2006 (QENS 2006),

edited by Sokol, P.E., Kaiser, H., Baxter, D., Pynn, R., Bossev, D.,

Leuschner, M., (Mater. Res. Soc., June 2006, Bloomington, IN) 13

(2007). (chrns)

Mamontov, E., Cole, D.R., “Quasielastic Neutron Scattering Study of

Dynamics of CaCl2 Aqueous Solution Confined in Vycor Glass,”

Phys. Chem. Chem. Phys. 8 (42), 4908 (2006). (chrns)

Mamontov, E., Udovic, T.J., Rush, J.J., Isnard, O., “Dynamics of

Hydrogen in Pr2Fe17H4 and Pr2Fe17H5 Studied by Quasielastic

Neutron Scattering,” J. Alloys Compd. 422 (1-2), 149 (2006).

(chrns)

Mamontov, E., Vlcek, L., Wesolowski, D.J., Cummings, P.T., Wang,

W., Anovitz, L.M., Rosenqvist, J., Brown, C.M., Garcia Sakai,

V., “Dynamics and Structure of Hydration Water on Rutile

and Cassiterite Nanopowders Studied by Quasielastic Neutron

Scattering and Molecular Dynamics Simulations,” J. Phys. Chem. C

111 (11), 4328 (2007). (chrns)

Mason, T.G., Graves, S.M., Wilking, J.N., Lin, M.Y., “Effective Structure

Factor of Osmotically Deformed Nanoemulsions,” J. Phys. Chem.

B 110 (44), 22097 (2006).

Mason, T.G., Graves, S.M., Wilking, J.N., Lin, M.Y., “Extreme

Emulsification: Formation and Structure of Nanoemulsions,”

Condens. Matter Phys. 9 (1), 193 (2006).

Masuda, T., Zheludev, A., Manaka, H., Chung, J.-H., “IPA-CuCl3: A S=1⁄2

Ladder with Ferromagnetic Rungs,” Low Temperature Physics:

24th International Conference on Low Temperature Physics,

edited by Takano, Y., Hershfield, S.P., Hill, S.O., Hirschfeld,

P.J., Goldman, A.M., (AIP, August 2005, Orlando, FL) 850, 1031

(2006). (chrns)

Matsuda, M., “Magnetic Structure of a Frustrated Antiferromagnetic

Spinel CdCr2O4 Studied by Spherical Neutron Polarimetry,”

Physica B 397 (1-2), 7 (2007). (chrns)

Matsuda, M., Takeda, M., Nakamura, M., Kakurai, K., Oosawa, A.,

Lelièvre-Berna, E., Chung, J.-H., Ueda, H., Takagi, H., Lee,

S.-H., “Spiral Spin Structure in the Heisenberg Pyrochlore Magnet

CdCr2O4,” Phys. Rev. B 75 (10), 104415 (2007). (chrns)

Matsuda, M., Ueda, H., Kikkawa, A., Tanaka, Y., Katsumata, K., Narumi,

Y., Inami, T., Ueda, Y., Lee, S.-H., “Spin-Lattice Instability to a

Fractional Magnetization State in the Spinel HgCr2O4,” Nature

Phys. 3 (6), 397 (2007). (chrns)

Matsuura, M., Hirota, K., Gehring, P.M., Ye, Z.-G., Chen, W., Shirane,

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Ferroelectric Compound (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3

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May, W.E., Cavanaugh, R.R., Turk, G.C., Winchester, M., Travis, J.,

Smith, M.V., DeRose, P., Choquette, S.J., Kramer, G.W., Sieber,

J.R., Greenberg, R.R., Lindstrom, R.M., Lamaze, G., Zeisler, R.,

Schantz, M., Sander, L., Phinney, K.W., Welch, M., Vetter, T., Pratt,

K.W., Scott, J.H., Small, J., Wight, S., Stranick, S.J., “Chemical

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McGillivray, D.J., Valincius, G., Vanderah, D.J., Febo-Ayala, W.,

Woodward, J.T., Heinrich, F., Kasianowicz, J.J., Lösche, M.,

“Molecular-Scale Structural and Functional Characterization of

Sparsely Tethered Bilayer Lipid Membranes,” Biointerphases 2

(1), 21 (2007).

McQueen, T., Huang, Q., Lynn, J.W., Berger, R.F., Klimczuk, T., Ueland,

B.G., Schiffer, P., Cava, R.J., “Magnetic Structure and Properties of

the S=5/2 Triangular Antiferromagnet α-NaFeO2,” Phys. Rev. B 76

(2), 024420 (2007).

McQueeney, R.J., Yethiraj, M., Montfrooij, W., Gardner, J.S., Metcalf, P.,

Honig, J.M., “Possible Large Spin-Phonon Coupling in Magnetite,”

Physica B 385-386 (1), 75 (2006).

Mehta, R., Dadmun, M.D., “Small Angle Neutron Scattering Studies on

Miscible Blends of Poly(Styrene-Ran-Vinyl Phenol) with Liquid

Crystalline Polyurethane,” Macromol. 39 (25), 8799 (2006).

(chrns)

Miao, P., Odette, G.R., Gould, J., Bernath, J., Miller, R., Alinger, M.,

Zanis, C., “The Microstructure and Strength Properties of MA957

Nanostructured Ferritic Alloy Joints Produced by Friction Stir and

Electro-Spark Deposition Welding,” J. Nucl. Mater., in press.

Micherdzinska, A.M., Bass, C.D., Crawford, B.E., Dawkins, J.M., Findley,

T.D., Heckel, B.R., Horton, J.C., Huffman, P.R., Luo, D., Markoff,

D.M., Mumm, H.P., Nico, J.S., Sarsour, M., Snow, W.M., Swanson,

H.E., “Proposed Measurement of the Parity-Violating Neutron

Spin Rotation in 4He,” Seventeenth International Conference

on Particles and Nuclei, edited by Barnes, P.D., Cooper, M.D.,

Eisenstein, R.A., van Hecke, H., Stephenson, G.J., (AIP, October

2005, Santa Fe, NM) 842, 799 (2006).

Millon, L.E., Nieh, M.-P., Hutter, J.L., Wan, W., “SANS Characterization

of an Anisotropic Poly(Vinyl Alcohol) Hydrogel with Vascular

Applications,” Macromol. 40 (10), 3655 (2007). (chrns)

Mitchell, J.W., Carpenter, S., “Parts Per Billion Doping and

Characterization of Uranium Distribution in an Epoxy Polymer

Matrix,” Anal. Chem. 78 (19), 6955 (2006).

Mock, E.B., Zukoski, C.F., “Investigating Microstructure of

Concentrated Suspensions of Anisotropic Particles Under Shear

by Small Angle Neutron Scattering,” J. Rheol. 51 (3), 541 (2007).

(chrns)

Mont, A.D., Kienzle, P.A., Watson, S.M., Borchers, J.A., Eckert, J.,

Sparks, P., Moyerman, S., Carey, M.J., “Determination of Complex

Magnetic Structures From Polarized Neutron Reflectivity Data by

Flexible Modeling of Depth-Dependent Vector Magnetization,”

IEEE Trans. Mag. 43 (7), 3346 (2007).

Motoyama, E.M., Yu, G., Vishik, I.M., Vajk, O.P., Mang, P.K., Greven,

M., “Spin Correlations in the Electron-Doped High-TransitionTemperature Superconductor Nd2-xCexCu4±δ,” Nature 445 (7124)

186 (2007).

Moyer Jr., R.O., Antao, S.M., Toby, B.H., Morin, F.G., Gilson, D.F.R.,

“Neutron Powder Diffraction and Solid-State Deuterium

NMR Studies of Ca2RuD6 and the Stability of Transition Metal

Hexahydride Salts,” J. Alloys Compd., in press.

Moyerman, S.M., Gannett, W., Borchers, J.A., Doucet, M., Carey, M.J.,

Sparks, P.D., Eckert, J.C., “Ferromagnetic Relaxation in Spin

Valves with Picoscale Antiferromagnetic Layers,” IEEE Trans. Mag.

42 (10), 2630 (2006).

Nagao, M., Seto, H., Faraone, A., “Neutron Spin Echo

Measurements on the Dynamics of Surfactant

Membranes,” Quasi-Elastic Neutron Scattering

Conference 2006 (QENS2006), edited by Sokol, P.E.,

Kaiser, H., Baxter, D., Pynn, R., Bossev, D., Leuschner,

M., (Mater. Res. Soc., June 2006, Bloomington, IN) 101

(2007). (chrns)

Nagao, M., Seto, H., Shibayama, M., Takeda, T., “Pressure

Effect on Semi-Microscopic Structures in a Nonionic

Microemulsion,” Physica B 385-386 (1), 783 (2006).

Nagao, M., Seto, H., Yamada, N.L., “Interaction Between

Droplets in a Ternary Microemulsion Evaluated by the

Relative Form Factor Method,” Phys. Rev. E 75 (6),

061401 (2007).

Nakatsuji, S., Nambu, Y., Onuma, K., Jonas, S., Broholm,

C., Maeno, Y., “Coherent Behaviour without Magnetic

Order of the Triangular Lattice Antiferromagnet

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(2007).

Nemes, N.M., Neumann, D.A., Livingston, R.A., “States

of Water in Hydrated C3S (Tricalcium Silicate) as a

Function of Relative Humidity,” J. Mater. Res. 21 (10),

2561 (2006).

Nettesheim, F., Wagner, N.J., “Fast Dynamics of Wormlike

Micellar Solutions,” Langmuir 23 (10), 5267 (2007).

(chrns)

Nguyen, T.V., Lin, G., Ohn, H., Hussey, D., Jacobson, D.,

Arif, M., “Measurements of Two-Phase Flow Properties

of the Porous Media Used in PEM Fuel Cells,” 210th

Electrochemical Society Meeting: Proton Exchange

Membrane Fuel Cells 6, edited by Fuller, T., Bock,

C., Cleghorn, S., Gasteiger, H., Jarvi, T., Mathias,

M., Murthy, M., Nguyen, T., Ramani, V., Stuve, E.,

Zawodzinski, T., (October 2006, Cancun, Mexico) 3 (1),

415 (2006).

Nico, J.S., “Neutron Lifetime Measurements,” 9th Conference

CIPAN 2006: Intersections of Particle and Nuclear

Physics, edited by Liss, T., (AIP, May 2006, Rio Grande,

Puerto Rico) 870, 132 (2006).

Nico, J.S., Dewey, M.S., Gentile, T.R., Mumm, H.P.,

Thompson, A.K., Fisher, B.M., Kremsky, I., Wietfeldt,

F.E., Chupp, T.E., Cooper, R.L., Beise, E.J., Kiriluk, K.G.,

Byrne, J., Coakley, K.J., “Observation of the Radiative

Decay Mode of the Free Neutron,” Nature 444 (7122),

1059 (2006).

Nieh, M.-P., Pencer, J., Katsaras, J., Qi, X., “Spontaneously

Forming Ellipsoidal Phospholipid Unilamellar Vesicles

and Their Interactions with Helical Domains of Saposin

C,” Langmuir 22 (26), 11028 (2006).

Norman, A.I., Fei, Y., Ho, D.L., Greer, S.C., “Folding and

Unfolding of Polymer Helices in Solution,” Macromol.

40 (7), 2559 (2007). (chrns)

Okabe, S., Karino, T., Nagao, M., Watanabe, S., Shibayama,

M., “Current Status of the 32m Small-Angle Neutron

Scattering Instrument, SANS-U,” Nucl. Instrum.

Methods Phys. Res., Sect. A 572 (2), 853 (2007).

NCNR 2007 ACCOMPLISHMENTS AND OPPORTUNITIES

73
Owejan, J.P., Trabold, T.A., Gagliardo, J.J., Jacobson, D.L.,

Carter, R.N., Hussey, D.S., Arif, M., “Voltage Instability in

a Simulated Fuel Cell Stack Correlated to Cathode Water

Accumulation,” J. Power Sources, in press.

Owejan, J.P., Trabold, T.A., Jacobson, D.L., Baker, D.R.,

Hussey, D.S., Arif, M., “In Situ Investigation of Water

Transport in an Operating PEM Fuel Cell Using Neutron

Radiography: Part 2 - Transient Water Accumulation in

an Interdigitated Cathode Flow Field,” Int. J. Heat Mass

Transfer 49 (25-26), 4721 (2006).

Owen, T., Pynn, R., Hammouda, B., Butler, A., “MetalDependent Self-Assembly of a Microbial Surfactant,”

Langmuir, in press. (chrns)

Pan, A.C., Rappl, T.J., Chandler, D., Balsara, N.P., “Neutron

Scattering and Monte Carlo Determination of the

Variation of the Critical Nucleus Size with Quench

Depth,” J. Phys. Chem. B 110 (8), 3692 (2006).

Pan, G., Schaefer, D.W., “Morphology and Water-Barrier

Properties of Silane Films on Aluminum and Silicon,”

Thin Solid Films 503 (1-2), 259 (2006).

Pande, C.S., Imam, M.A., “Nucleation and Growth Kinetics in

High Strength Low Carbon Ferrous Alloys,” Mater. Sci.

Eng., A 457 (1-2), 69 (2007).

Paskevicius, M., Buckley, C.E., “Analysis of Polydisperse

Bubbles in the Aluminum-Hydrogen System Using a SizeDependent Contrast,” J. Appl. Cryst. 39 (5), 676 (2006).

(chrns)

Patel, A.J., Balsara, N.P., “Observing Nucleation Close to the

Binodal by Perturbing Metastable Polymer Blends,”

Macromol. 40 (5), 1675 (2007). (chrns)

Paul, R.L., “Determination of Sulfur in Steels by

Radiochemical Neutron Activation Analysis with Liquid

Scintillation Counting,” J. Radioanal. Nucl. Chem., in

press.

Peral, I., Íñiguez, J., “Amorphization Induced by Pressure:

Results for Zeolites and General Implications,” Phys. Rev.

Lett. 97 (22), 225502 (2006).

Peterson, V.K., Brown, C.M., Livingston, R.A., “Quasielastic

and Inelastic Neutron Scattering Study of the Hydration

of Monoclinic and Triclinic Tricalcium Silicate,” Chem.

Phys. 326 (2-3), 381 (2006).

Peterson, V.K., Garci Juenger, M.C., “Hydration of Tricalcium

Silicate: Effects of CaCl2 and Sucrose on Reaction

Kinetics and Product Formation,” Chem. Mater. 18 (24),

5798 (2006).

Peterson, V.K., Garci Juenger, M.C., “Time-Resolved

Quasielastic Neutron Scattering Study of the Hydration of

Tricalcium Silicate: Effects of CaCl2 and Sucrose,” Physica

B 385-386 (1), 222 (2006).

Peterson, V.K., Garci-Juenger, M.C., “Tricalcium Silicate

Hydration Studied Using Quasielastic Neutron Scattering:

Insights on the Effects of Sucrose,” 12th International

Congress of the Chemistry of Cement, edited by

Beaudoin, J., (ICCC, July 2007, Montréal, Canada) 00362

(2007).

Peterson, V.K., Liu, Y., Brown, C.M., Kepert, C.J., “Neutron

Powder Diffraction Study of D2 Sorption in Cu3(1,3,5-

Benzenetricarboxylate)2,” J. Amer. Chem Soc. 128 (49),

15578 (2006).

Peterson, V.K., Neumann, D.A., Livingston, R.A., “Hydration of

Cement: the Application of Quasielastic and Inelastic Neutron

Scattering,” Physica B 385-386 (1), 481 (2006).

Phelan, D., Louca, D., Kamazawa, K., Lee, S.-H., Ancona, S.N.,

Rosenkranz, S., Motome, Y., Hundley, M.F., Mitchell, J.F.,

Moritomo, Y., “Spin Incommensurability and Two Phase

Competition in Cobaltites,” Phys. Rev. Lett. 97 (23), 235501

(2006). (chrns)

Plomp, J., Barker, J.G., de Haan, V.O., Bouwman, W.G., van Well, A.A.,

“Neutron Refraction by Cylindrical Metal Wires,” Nucl. Instrum.

Methods Phys. Rev., Sect. A 574 (2), 324 (2007). (chrns)

Point, D., Davis, W.C., Christopher, S.J., Ellisor, M.B., Pugh, R.S., Becker,

P.R., Donard, O.F.X., Porter, B.J., Wise, S.A., “Development and

Application of an Ultratrace Method for Speciation of Organotin

Compounds in Cryogenically Archived and Homogenized

Biological Materials,” Anal. Bioanal. Chem. 387 (7), 2343 (2007).

Popelka-Filcoff, R.S., Craig, N., Glascock, M.D., Robertson, J.D.,

Aldenderfer, M., Speakman, R.J., “Instrumental Neutron

Activation Analysis of Ochre Artifacts From Jiskairumoko,

Peru,” Archaeological Chemistry: Analytical Techniques and

Archaeological Interpretation, edited by Glascock, M.D.,

Speakman, R.J., Popelka-Filcoff, R.S., (ACS Symp. Ser., March

2006, Atlanta, GA) 968, 480 (2007).

Popelka-Filcoff, R.S., Miksa, E.J., Robertson, J.D., Glascock, M.D.,

Wallace, H., “Elemental Analysis and Characterization of Ochre

Sources From Southern Arizona,” J. Archaeol. Sci., in press.

Popelka-Filcoff, R.S., Robertson, J.D., Glascock, M.D., Descantes, C.,

“Trace Element Characterization of Ochre From Geological

Sources,” J. Radioanal. Nucl. Chem. 272 (1), 17 (2007).

Poster, D.L., Kucklick, J.R., Schantz, M.M., Porter, B.J., Sander, L.C.,

Wise, S.A., “New Developments in Standard Reference Materials

(SRMs) for Environmental Forensics,” Environ. Forens. 8 (1-2),

181 (2007).

Pozzo, D.C., Walker, L.M., “Shear Orientation of Nanoparticle Arrays

Templated in a Thermoreversible Block Copolymer Micellar

Crystal,” Macromol., in press. (chrns)

Pozzo, D.C., Walker, L.M., “Small-Angle Neutron Scattering of Silica

Nanoparticles Templated in PEO-PPO-PEO Cubic Crystals,”

Colloids Surf., A 294 (1-3), 117 (2007). (chrns)

Prabhu, V.M., Vogt, B.D., Kang, S., Rao, A., Lin, E.K., Satija, S.K.,

Turnquest, K., “Direct Measurement of the In-Situ Developed

Latent Image: the Residual Swelling Fraction,” Advances in Resist

Materials and Processing Technology XXIV, edited by Lin, Q.,

(SPIE Conf. Proc., March 2007) 6519, 651910 (2007).

Prabhu, V.M., Vogt, B.D., Wu, W.-L., Douglas, J.F., Lin, E.K., Satija, S.K.,

Goldfarb, D.L., Ito, H., “Interfacial Structure of Photoresist Thin

Films in Developer Solutions,” Advances in Resist Technology and

Processing XXII, edited by Sturtevant, J.L., (SPIE Conf. Proc., May

2005) 5753, 292 (2005).

Prime, M.B., Gnäupel-Herold, T., Baumann, J.A., Lederich, R.J.,

Bowden, D.M., Sebring, R.J., “Residual Stress Management in a

Thick, Dissimilar Aluminum Alloy Friction Stir Weld,” Acta Mater.

54 (15), 4013 (2006).

Pushin, D.A., Arif, M., Jacobson, D.L., Doe, C.K., Cory, D.G.,

“Reciprocal Space Neutron Imaging,” Physica B 385-386 (2), 1402

(2006).

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Pushin, D.A., Cory, D.G., Arif, M., Jacobson, D.L., Huber, M.G.,

“Reciprocal Space Approaches to Neutron Imaging,” Appl. Phys.

Lett. 90 (22), 224104 (2007).

Quintanilla, J.A., Chen, J.T., Reidy, R.F., Allen, A.J., “Versatility and

Robustness of Gaussian Random Fields for Modelling Random

Media,” Modell. Simul. Mater. Sci. Eng. 15 (4), S337 (2007).

(chrns)

Rao, A., Kang, S., Vogt, B.D., Prabhu, V.M., Lin, E.K., Wu, W.-L.,

Muthukumar, M., “Effect of Deprotection Extent on Swelling and

Dissolution Regimes of Thin Polymer Films,” Langmuir 22 (24),

10009 (2006). (chrns)

Rathgeber, S., Monkenbusch, M., Hedrick, J.L., Trollsås, M., Gast,

A.P., “Starlike Dendrimers in Solutions: Structural Properties

and Internal Dynamics,” J. Chem. Phys. 125 (20), 204908 (2006).

(chrns)

Révay, Z., “Comparison of the Analytical Sensitivities for Non-1/v

Elements in Different Neutron Beams,” Nucl. Instrum. Methods

Phys. Res., Sect. B, in press.

Ridley, M.K., Hackley, V.A., Machesky, M.L., “Characterization and

Surface-Reactivity of Nanocrystalline Anatase in Aqueous

Solutions,” Langmuir 22 (26), 10972 (2006).

Rijssenbeek, J., Gao, Y., Hanson, J., Huang, Q., Jones, C., Toby, B.,

“Crystal Structure Determination and Reaction Pathway of AmideHydride Mixtures,” J. Alloys Compd., in press.

Roberts, J., Maddula, R., Clackdoyle, R., DiBella, E., Fu, Z., “The Effect

of Acquisition Interval and Spatial Resolution on Dynamic Cardiac

Imaging with a Stationary SPECT Camera,” Phys. Med. Biol., in

press.

Rodriguez, J.A., Moss, S.C., Robertson, J.L., Copley, J.R.D., Neumann,

D.A., Major, J., “Neutron Scattering Studies of Short-Range Order,

Atomic Displacements, and Effective Pair Interactions in a NullMatrix 62Ni0.52Pt0.48 Crystal,” Phys. Rev. B 74 (10), 104115 (2006).

(chrns)

Roh, J.-H., Curtis, J.E., Azzam, S., Novikov, V.N., Peral, I., Chowdhuri,

Z., Gregory, R.B., Sokolov, A.P., “Influence of Hydration on the

Dynamics of Lysozyme,” Biophys. J. 91 (7), 2573 (2006). (chrns)

Ruegg, M.L., Reynolds, B.J., Lin, M.Y., Lohse, D.J., Balsara, N.P.,

“Minimizing the Concentration of Diblock Copolymer Needed

to Organize Blends of Weakly Segregated Polymers by Tuning

Attractive and Repulsive Interactions,” Macromol. 40 (4), 1207

(2007).

Ruegg, M.L., Reynolds, B.J., Lin, M.Y., Lohse, D.J., Krishnamoorti, R.,

Balsara, N.P., “Effect of Pressure on a Multicomponent A/B/AC Polymer Blend with Attractive and Repulsive Interactions,”

Macromol. 40 (2), 355 (2007).

Ruiz-Hervias, J., Luzin, V., Prask, H., Gnaeupel-Herold, T., Elices, M.,

“Effect of Thermo-Mechanical Treatments on Residual Stresses

Measured by Neutron Diffraction in Cold-Drawn Steel Rods,”

Mater. Sci. Eng., A 435-436, 725 (2006).

Russo, D., “The Impact of Kosmotropes and Chaotropes on Bulk and

Hydration Shell Water Dynamics in a Model Peptide Solution,”

Chem. Phys., in press. (chrns)

Russo, D., Hura, G.L., Copley, J.R.D., “Effects of Hydration Water on

Protein Methyl Group Dynamics in Solution,” Phys. Rev. E 75 (4),

040902 (2007). (chrns)

Russo, P.L., Wiebe, C.R., Uemura, Y.J., Savici, A.T.,

MacDougall, G.J., Rodriguez, J., Luke, G.M., Kaneko,

N., Eisaki, H., Greven, M., Vajk, O.P., Ono, S., Ando,

Y., Fujita, K., Kojima, K.M., Uchida, S., “Muon Spin

Relaxation Study of Superconducting

Bi2Sr2-xLaxCuO6+δ,” Phys. Rev. B 75 (5), 054511 (2007).

Ryu, D.Y., Wang, J.-Y., Lavery, K.A., Drockenmuller, E., Satija,

S.K., Hawker, C.J., Russell, T.P., “Surface Modification

with Cross-Linked Random Copolymers: Minimum

Effective Thickness,” Macromol. 40 (12), 4296 (2007).

Santonicola, M.G., Yocum II, M.A., Lenhoff, A.M.,

Kaler, E.W., “Self-Assembly of Medium-Chain Alkyl

Monoglucosides in Ammonium Sulfate Solutions with

Poly(Ethylene Glycol),” Langmuir 23 (10), 5358 (2007).

(chrns)

Savici, A.T., Zaliznyak, I.A., Gu, G.D., Erwin, R., “Stripeless

Incommensurate Magnetism in Strongly Correlated

Oxide La1.5Sr0.5CoO4,” Phys. Rev. B 75 (18), 184443

(2007).

Sen, S., Xie, Y., Kumar, S.K., Yang, H., Bansal, A., Ho,

D.L., Hall, L., Hooper, J.B., Schweizer, K.S., “Chain

Conformations and Bound-Layer Correlations in

Polymer Nanocomposites,” Phys. Rev. Lett. 98 (12),

128302 (2007). (chrns)

Seo, P.-N., Coakley, K.J., Doyle, J.M., DuBose, F.H., Golub,

R., Korobkina, E., Lamoreaux, S.K., Mumm, H.P.,

O’Shaughnessy, C.M., Palmquist, G.R., Thompson, A.K.,

Yang, G.L., Yang, L., Huffman, P.R., “Progress Towards a

Precision Measurement of the Neutron Lifetime Using

Magnetically Trapped Ultracold Neutrons,” Seventeenth

International Conference on Particles and Nuclei,

edited by Barnes, P.D., Cooper, M.D., Eisenstein, R.A.,

van Hecke, H., Stephenson, G.J., (AIP, October 2005,

Santa Fe, NM) 842, 811 (2006).

Seo, Y.-S., Ahmad, F., Shin, K., Song, J.-M., Kim, J.-S.,

Rafailovich, M.H., Sokolov, J., Satija, S.K., “Interfacial

Behaviour of Randomly Charged Sulfonated Polystyrene

(PSS) at the Air/Water Interface,” Colloids Surf., A, in

press.

Seo, Y.-S., Satija, S., “No Intrinsic Depletion Layer on a

Polystyrene Thin Film at a Water Interface,” Langmuir

22 (17), 7113 (2006).

Sharpless, K.E., Anderson, D.L., Betz, J.M., Butler, T.A.,

Capar, S.G., Cheng, J., Fraser, C.A., Gardner, G., Gay,

M.L., Howell, D.W., Ihara, T., Khan, M.A., Lam, J.W.,

Long, S.E., McCooeye, M., Mackey, E.A., Mindak, W.R.,

Mitvalsky, S., Murphy, K.E., NguyenPho, A., Phinney,

K.W., Porter, B.J., Roman, M., Sander, L.C., Satterfield,

M.B., Scriver, C., Sturgeon, R., Thomas, J.B., Vocke Jr.,

R.D., Wise, S.A., Wood, L.J., Yang, L., Yen, J.H., Ziobro,

G.C., “Preparation and Characterization of a Suite of

Ephedra-containing Standard Reference Materials,” J.

AOAC Int. 89 (6), 1483 (2006).

Sheu, E.Y., “Small Angle Scattering and Asphaltenes,” J. Phys.:

Condens. Matter 18 (36), S2485 (2006).

Sieber, J.R., Mackey, E.A., Marlow, A.F., Paul, R., Martin, R.,

“Validation of an Alkali Reaction, Borate Fusion, X-Ray

Fluorescence Method for Silicon Metal,” Powder Diffr.

22 (2), 146 (2007).

NCNR 2007 ACCOMPLISHMENTS AND OPPORTUNITIES

75
Siegmund, O.H.W., Vallerga, J.V., Martin, A., Feller, B.,

Arif, M., Hussey, D.S., Jacobson, D.L., “A High Spatial

Resolution Event Counting Neutron Detector Using

Microchannel Plates and Cross Delay Line Readout,”

Nucl. Instrum. Methods Phys. Res., Sect. A, in press.

Siegmund, O.H., Vallerga, J.V., Tremsin, A.S., Mcphate, J.,

Feller, B., “High Spatial Resolution Neutron Sensing

Microchannel Plate Detectors,” Nucl. Instrum. Methods

Phys. Res., Sect. A 576 (1), 178 (2007).

Simons, D.S., Downing, R.G., Lamaze, G.P., Lindstrom, R.M.,

Greenberg, R.R., Paul, R.L., Schiller, S.B., Guthrie,

W.F., “Development of Certified Reference Materials

of Ion-Implanted Dopants in Silicon for Calibration of

Secondary Ion Mass Spectrometers,” J. Vac. Sci. Technol.,

B 25 (4), 1365 (2007).

Simons, D., Kim, K., Benbalagh, R., Bennett, J., Chew, A.,

Gehre, D., Hasegawa, T., Hitzman, C., Ko, J., Lindstrom,

R., MacDonald, B., Magee, C., Montgomery, N., Peres, P.,

Ronsheim, P., Yoshikawa, S., Schuhmacher, M., Stockwell,

W., Sykes, D., Tomita, M., Toujou, F., Won, J., “RoundRobin Study of Arsenic Implant Dose Measurement in

Silicon by SIMS,” Appl. Surf. Sci. 252 (19), 7232 (2006).

Singh, I., Shankaran, H., Beauharnois, M.E., Xiao, Z.,

Alexandridis, P., Neelamegham, S., “Solution Structure

of Human von Willebrand Factor Studied Using Small

Angle Neutron Scattering,” J. Biol. Chem. 281 (50),

38266 (2006). (chrns)

Sirota, E.B., Lin, M.Y., “Physical Behavior of Asphaltenes,”

Energy Fuels, in press.

Skripov, A.V., Buzlukov, A.L., Soloninin, A.V., Voronin, V.I.,

Berger, I.F., Udovic, T.J., Huang, Q., Rush, J.J.,

“Hydrogen Motion and Site Occupation in Ti2CoHx(Dx):

NMR and Neutron Scattering Studies,” Physica B 392

(1-2), 353 (2007).

Smith, G.S., Kuhl, T.L., Hamilton, W.A., Mulder, D.J., Satija,

S., “Structure of Confined Polymer Thin Films Subject to

Shear,” Physica B 385-386 (1), 700 (2006).

Snyder, M.A., Lee, J.A., Davis, T.M., Scriven, L.E., Tsapatsis, M.,

“Silica Nanoparticle Crystals and Ordered Coatings Using

Lys-Sil and a Novel Coating Device,” Langmuir, in press.

Sokolov, A.P., Roh, J.H., Mamontov, E., García Sakai, V.,

“Role of Hydration Water in Dynamics of Biological

Macromolecules,” Chem. Phys., in press. (chrns)

Stalick, J.K., Waterstrat, R.M., “The Zirconium-Platinum Phase

Diagram,” J. Alloys Compd. 430 (1-2), 123 (2007).

Stanley, C., Rau, D.C., “Preferential Hydration of DNA: the

Magnitude and Distance Dependence of Alcohol and

Polyol Interactions,” J. Biophys. 91 (3), 912 (2006).

Stone, M.B., Broholm, C., Reich, D.H., Schiffer, P.,

Tchernyshyov, O., Vorderwisch, P., Harrison, N., “FieldDriven Phase Transitions in a Quasi-Two-Dimensional

Quantum Antiferromagnet,” New J. Phys. 9 (31), 1

(2007).

Stone, M.B., Tian, W., Granroth, G.E., Lumsden, M.D., Chung,

J.-H., Mandrus, D.G., Nagler, S.E., “Spin Dynamics of the

Low-Dimensional Magnet (CH3)2NH2CuCl3,” Physica B

385-386 (1), 438 (2006). (chrns)

Sun, Y.-S., Jeng, U.-S., Huang, Y.-S., Liang, K.S., Lin, T.-L., Tsao, C.-S.,

“Complementary SAXS and SANS for Structural Characteristics

of a Polyurethethane Elastomer of Low Hard-Segment Content,”

Physica B 385-386 (1), 650 (2006).

Swallen, S.F., Kearns, K.L., Mapes, M.K., Kim, Y.S., McMahon, R.J.,

Ediger, M.D., Wu, T., Yu, L., Satija, S., “Organic Glasses with

Exceptional Thermodynamic and Kinetic Stability,” Science 315,

353 (2007).

Terech, P., Friol, S., “Rheometry of an Androstanol Steroid Derivative

Paramagnetic Organogel. Methodology for a Comparison with a

Fatty Acid Organogel,” Tetrahedron 63 (31), 7366 (2007). (chrn

Toby, B.H., “Classification and Use of Powder Diffraction Data,”

International Tables for Crystallography, Volume G: Definition

and Exchange of Crystallographic Data, edited by Hall, S.,

McMahon, B., (IUCr, Springer, 2006) G (3.3), 117 (2006).

Toby, B.H., “Powder Dictionary (pdCIF),” International Tables

for Crystallography, Volume G: Definition and Exchange of

Crystallographic Data, edited by Hall, S., McMahon, B., (IUCr,

Springer, 2006) G (4.2), 258 (2006).

Trabold, T.A., Owejan, J.P., Jacobson, D.L., Arif, M., Huffman, P.R., “In

Situ Investigation of Water Transport in an Operating PEM Fuel

Cell Using Neutron Radiography: Part 1 – Experimental Method

and Serpentine Flow Field Results,” Int. J. Heat Mass Transfer 49

(25-26), 4712 (2006).

Tremsin, A.S., Hussey, D.S., Downing, R.G., Feller, W.B., Mildner, D.F.R.,

Jacobson, D.L., Arif, M., Siegmund, O.H.W., “Neutron Collimation

with Microchannel Plates: Calibration of Existing Technology

and Near Future Possibilities,” IEEE Trans. Nucl. Sci. 54 (2), 362

(2007).

Triftaridou, A.I., Vamvakaki, M., Patrickios, C.S., “Cationic Amphiphilic

Model Networks Based on Symmetrical ABCBA Pentablock

Terpolymers: Synthesis, Characterization, and Modeling,”

Biomacromol. 8 (5), 1615 (2007). (chrns)

Triolo, R., Lo Celso, F., Benfante, V., Gorgoni, C., Barker, J., Butler, P.,

Ruffo, I., “Fingerprinting White Marbles of Archaeometric Interest

by Means of Combined SANS and USANS,” Nuovo Cimento C 30

(1), 129 (2006). (chrns)

Turner, S., Sieber, J.R., Vetter, T.W., Zeisler, R., Marlow, A.F., MorenoRamirez, M.G., Davis, M.E., Kennedy, G.J., Borghard, W.G., Yang,

S., Navrotsky, A., Toby, B.H., Kelly, J.F., Fletcher, R.A., Windsor,

E.S., Verkouteren, J.R., Leigh, S.D., “Characterization of Chemical

Properties, Unit Cell Parameters, and Particle Size Distribution

of Three Zeolite Reference Materials: RM 8850 – Zeolite Y, RM

8851 – Zeolite A and RM 8852 – Ammonium ZSM-5 Zeolite,”

Microporous Mesoporous Mater., in press.

Udovic, T.J., Zhou, W., Wu, H., Brown, C.M., Rush, J.J., Yildirim, T.,

Mamontov, E., Isnard, O., “Neutron Vibrational Spectroscopy of

the Pr2Fe17-Based Hydrides,” J. Alloys Compd., in press.

Vaknin, D., Bu, W., Satija, S.K., Travesset, A., “Ordering by Collapse:

Formation of Bilayer and Trilayer Crystals by Folding Langmuir

Monolayers,” Langmuir 23 (4), 1888 (2007).

Vanderah, T.A., Lufaso, M.W., Adler, A.U., Levin, I., Nino, J.C.,

Provenzano, V., Schenck, P.K., “Subsolidus Phase Equilibria and

Properties in the System Bi2O3:Mn2O3±x:Nb2O5,” J. Solid Stat

Chem. 179 (11), 3467 (2006).

Verruto, V.J., Kilpatrick, P.K., “Preferential Solvent Partitioning within

Asphaltenic Aggregates Dissolved in Binary Solvent Mixtures,”

Energy Fuels 21 (3), 1217 (2007). (chrns)

76
Viciu, L., Huang, Q., Morosan, E., Zandbergen, H.W., Greenbaum, N.I.,

McQueen, T., Cava, R.J., “Structure and Basic Magnetic Properties

of the Honeycomb Lattice Compounds Na2Co2TeO6 and

Na­3Co2SbO6,” J. Solid State Chem. 180 (3), 1060 (2007

Viciu, L., Zandbergen, H.W., Xu, Q., Huang, Q., Lee, M., Cava, R.J.,

“Structure and Magnetic Properties of the Orthorhombic n = 2

Ruddlesden-Popper Phases Sr3Co2O5+δ (δ = 0.91, 0.64 and 0.38),”

J. Solid State Chem. 179 (2), 500 (2006).

Vogt, B.D., Kang, S., Prabhu, V.M., Lin, E.K., Satija, S.K., Turnquest,

K., Wu, W.-L., “Measurements of the Reaction-Diffusion Front of

Model Chemically Amplified Photoresists with Varying Photoacid

Size,” Macromol. 39 (24), 8311 (2006).

Vogt, B.D., Kang, S., Prabhu, V.M., Rao, A., Lin, E.K., Wu, W.-L., Satija,

S.K., Turnquest, K., “Influence of Base Additives on the ReactionDiffusion Front of Model Chemically Amplified Photoresists,” J.

Vac. Sci. Technol., B 25 (1), 175 (2007).

Vogt, B.D., Soles, C.L., Prabhu, V.M., Satija, S.K., Lin, E.K., Wu, W.-L.,

“Water Distribution within Immersed Polymer Films,” Advances in

Resist Technology and Processing XXII, edited by Sturtevant, J.L.,

(SPIE Conf. Proc., May 2005) 5753, 31 (2005).

Wakimoto, S., Samara, G.A., Grubbs, R.K., Venturini, E.L., Boatner,

L.A., Xu, G., Shirane, G., Lee, S.-H., “Dielectric Properties and

Lattice Dynamics of Ca-Doped K0.95Li0.05TaO3,” Phys. Rev. B 74 (5),

054101 (2006). (chrns)

Wang, C., Araki, T., Watts, B., Harton, S., Koga, T., Basu, S., Ade, H.,

“Resonant Soft X-Ray Reflectivity of Organic Thin Films,” J. Vac.

Sci. Technol., A 25 (3), 575 (2007).

Wang, Y.C., Yang, H.F., Huang, Q., Duan, L.B., Lynn, J.W., Rao, G.H.,

“Magnetic and Crystal Structures of Polymorphic Pr­5Si2Ge2,” Phy

Rev. B, in press.

Wang, Z., Hertel, N.E., Lennox, A., “Calibration of the Borated Ion

Chamber at NIST Reactor Thermal Column,” Radiat. Prot.

Dosim., in press.

Whitby, C.P., Djerdjev, A.M., Beattie, J.K., Warr, G.G., “In Situ

Determination of the Size and Polydispersity of Concentrated

Emulsions,” Langmuir 23 (4), 1694 (2007). (chrns)

Whitten, A.E., Jacques, D.A., Hammouda, B., Hanley, T., King, G.F.,

Guss, J.M., Trewhella, J., Langley, D.B., “The Structure of the

KinA-Sda Complex Suggests an Allosteric Mechanism of Histidine

Kinase Inhibition,” J. Mol. Biol. 368 (2), 407 (2007). (chrns)

Wiebe, C.R., Janik, J.A., MacDougall, G.J., Luke, G.M., Garrett, J.D.,

Zhou, H.D., Jo, Y.-J., Balicas, L., Qiu, Y., Copley, J.R.D., Yamani, Z.,

Buyers, W.J.L., “Gapped Itinerant Spin Excitations Account for

Missing Entropy in the Hidden-Order State of URu2Si2.,” Nature

Phys. 3 (2), 96 (2007). (chrns)

Wietfeldt, F.E., Huber, M., Black, T.C., Kaiser, H., Arif, M., Jacobson,

D.L., Werner, S.A., “Measuring the Neutron’s Mean Square Charge

Radius Using Neutron Interferometry,” Physica B 385-386 (2),

1374 (2006).

Wilson, K.S., Allen, A.J., Washburn, N.R., Antonucci, J.M., “Interphase

Effects in Dental Nanocomposites Investigated by Small-Angle

Neutron Scattering,” J. Biomed. Mater. Res. 81 (1), 113 (2007).

(chrns)

Wilson, S.D., Li, S., Dai, P., Bao, W., Chung, J.-H., Kang, H.J., Lee, S.-

H., Komiya, S., Ando, Y., Si, Q., “Evolution of Low-Energy Spin

Dynamics in the Electron-Doped High-Transition-Temperature

Superconductor Pr0.88LaCe0.12CuO4-δ,” Phys. Rev. B 74 (14),

144514 (2006). (chrns)

Wilson, S.D., Li, S., Woo, H., Dai, P., Mook, H.A., Frost, C.D.,

Komiya, S., Ando, Y., “High-Energy Spin Excitations in

the Electron-Doped Superconductor Pr0.88LaCe0.12CuO4-δ

with Tc = 12 K,” Phys. Rev. Lett. 96 (15), 157001 (2006).

(chrns)

Wilson, S.D., Li, S., Zhao, J., Mu, G., Wen, H.-H., Lynn, J.W.,

Freeman, P.G., Regnault, L.-P., Habicht, K., Dai, P.,

“Nature of the Quantum Spin Correlations Through

the Superconducting-Normal Phase Transition in

Electron-Doped Superconducting Pr0.88LaCe0.12­CuO4

Proceedings of the National Academy of Sciences, in

press.

Wiren, Z.Q., Kepa, H., Brown, C.M., Leao, J., Kolesnik,

S., Dabrowski, B., Furdyna, J.K., Giebultowicz,

T.M., “Studies of Intrinsic Exchange Interactions

in Zn(Mn)O, Zn(Mn)S and Zn(Mn)Te at 4

kbar by Inelastic Neutron Scattering,” Physics of

Semiconductors: 28th International Conference on

the Physics of Semiconductors, edited by Jantsch, W.,

Schaffler, F., (AIP, July 2006, Vienna, Austria) 893, 1197

(2007). (chrns)

Woodward, R.C., Heeris, J., St. Pierre, T.G., Saunders, M.,

Gilbert, E.P., Rutnakornpituk, M., Zhang, Q., Riffle, J.S.,

“A Comparison of Methods for the Measurement of the

Particle-Size Distribution of Magnetic Nanoparticles,” J.

Appl. Cryst. 40, s495 (2007). (chrn

Wu, H., Hartman, M.R., Udovic, T.J., Rush, J.J., Zhou, W.,

Bowman Jr., R.C., Vajo, J.J., “Structure of the Novel

Ternary Hydrides Li4Tt2D (Tt = Si and Ge),” Acta

Crystallogr., Sect. B: Struct. Sci. B63, 63 (2007).

Wu, H., Zhou, W., Udovic, T.J., Rush, J.J., “Hydrogen Storage

in a Novel Destabilized Hydride System, Ca2SiHx: Effects

of Amorphization,” Chem. Mater.

19 (2), 329 (2007).

Wu, H., Zhou, W., Udovic, T.J., Rush, J.J., “Structure and

Hydrogenation Properties of the Ternary Alloys

Ca2-xMgxSi (0 ≤ x ≤ 1),” J. Alloys Compd., in press.

Wu, H., Zhou, W., Udovic, T.J., Rush, J.J., Yildirim, T.,

“Structure and Hydrogen Bonding in CaSiD1+x: Issues

About Covalent Bonding,” Phys. Rev. B 74 (22), 224101

(2006).

Wu, H., Zhou, W., Udovic, T.J., Rush, J.J., Yildirim, T.,

“Structure and Vibrational Spectra of Calcium Hydride

and Deuteride,” J. Alloy. Compd. 436 (1-2), 51 (2007).

Wu, H., Zhou, W., Udovic, T.J., Rush, J.J., Yildirim, T.,

Huang, Q., Bowman Jr., R.C., “Structure and Interstitial

Deuterium Sites of β-phase ZrNi Deuteride,” Phys. Rev.

B 75 (6), 064105 (2007).

Wu, H., Zhou, W., Yildirim, T., “Hydrogen Storage in a

Prototypical Zeolitic Imidazolate Framework-8,” J. Amer.

Chem. Soc. 129 (17), 5314 (2007).

Wu, S.Y., Li, W.-H., Yang, C.C., Lynn, J.W., Liu, R.S.,

“Magnetic Ordering of Mn and Ru in (La0.52Ba0.48)

(Mn0.51Ru0.49)O3,” Physica Status Solidi B 244 (6),

2233 (2007).

NCNR 2007 ACCOMPLISHMENTS AND OPPORTUNITIES

77
Wu, W.-L., Prabhu, V.M., Lin, E.K., “Identifying Materials

Limits of Chemically Amplified Photoresists,” Advances

in Resist Materials and Proceedings Technology XXVI,

edited by Lin, Q., (SPIE Conf. Proc., April 2007) 6519,

651902 (2007).

Xiao, Y.G., Huang, Q., Ouyang, Z.W., Lynn, J.W., Liang, J.K.,

Rao, G.H., “Crystal and Magnetic Structure of Laves

Phase Compound NdCo2 in the Temperature Range

Between 9 and 300 K,” J. Alloys. Compd. 420 (1-2), 29

(2006).

Xu, G., Broholm, C., Soh, Y.-A., Aeppli, G., DiTusa, J.F., Cheng,

Y., Kenzelmann, M., Frost, C.D., Ito, T., Oka, K., Takagi,

H., “Mesoscopic Phase Coherence in a Quantum Spin

Fluid,” Science, in press.

Xu, G., Gehring, P.M., Shirane, G., “Coexistence and

Competition of Local- and Long-Range Polar Orders in

a Ferroelectric Relaxor,” Phys. Rev. B 74 (10), 104110

(2006).

Yamaura, K., Huang, Q., Akaishi, M., Takayama-Muromachi,

E., “Superconductivity in the Hexagonal-Layered

Molybdenum Carbide η-Mo3C2,” Phys. Rev. B 74 (18),

184510 (2006).

Yamaura, K., Huang, Q., Zhang, L., Takada, K., Baba, Y.,

Nagai, T., Matsui, Y., Kosuda, K., Takayama-Muromachi,

E., “Magnetic Properties of the Calcium Ferrite-Type

Li0.92Mn2O4,” J. Magn. Magn. Mater. 310 (2), 1578 (2007).

Yamaura, K., Huang, Q., Zhang, L., Takada, K., Baba, Y., Nagai,

T., Matsui, Y., Kosuda, K., Takayama-Muromachi, E., “PostSpinel Transition and Magnetic Properties of LiMn2O4,”

Phys. Stat. Sol. B 244 (1), 285 (2007).

Yang, C.C., Chung, M.K., Li, W.-H., Chan, T.S., Liu, R.S.,

Lien, Y.H., Huang, C.Y., Chan, Y.Y., Yao, Y.D., Lynn, J.W.,

“Magnetic Instability and Oxygen Deficiency in Na-Doped

TbMnO3,” Phys. Rev. B 74 (9), 094409 (2006).

Yang, C.C., Chung, M.K., Wu, S.Y., Li, W.-H., Yao, Y.D., Lynn,

J.W., Chan, T.S., Liu, R.S., “Magnetic Order and Spin

Fluctuations in Ni-Rich Li0.9Ni1.1O2,” Physica B

385-386 (1), 432 (2006).

Yang, Z., Wong-Ng, W., Cook, L.P., Kaduk, J.A., Huang, Q.Z.,

“X-Ray and Neutron Powder Diffraction Studies of

(Ba1-xSrx)Y2CuO5,” Powder Diffr. 21 (3), 200 (2006).

Ye, F., Lorenz, B., Huang, Q., Wang, Y.Q., Sun, Y.Y.,

Chu, C.W., Fernandez-Baca, J.A., Dai, P., Mook,

H.A., “Incommensurate Magnetic Structure in the

Orthorhombic Perovskite ErMnO­3­,” Phys. Rev

in press.

Yi, Z., Bossev, D.P., “The Effect of the Unsaturated Double

Bond on the Bending Elasticity of Lipid Membranes

Studied by Neutron Spin Echo,” Quasi-Elastic Neutron

Scattering Conference 2006 (QENS2006), edited by

Sokol, P.E., Kaiser, H., Baxter, D., Pynn, R., Bossev,

D., Leuschner, M., (Mater. Res. Soc., June 2006,

Bloomington, IN) 123 (2007). (chrns)

Zambrano, E., Kotlarchyk, M., Langner, M., Faraone, A.,

“Isomeric and Concentration Effects of C4-Cosurfactants

on Four-Component Microemulsions Investigated by

Neutron Spin-Echo and Small-Angle Scattering,” J. Phys.:

Condens. Matter 18 (36), S2451 (2006). (chrn

Zank, J., Reynolds, P.A., Jackson, A.J., Baranyai, K.J., Perriman, A.W.,

Barker, J.G., Kim, M.-H., White, J.W., “Aggregation in a High

Internal Phase Emulsion Observed by SANS and USANS,” Physica

B 385-386 (1), 776 (2006). (chrns)

Zarestky, J.L., Moze, O., Lynn, J.W., Chen, Y., Lograsso, T.A., Schlagel,

D.L., “Spin-Wave Dispersion in Magnetostrictive Fe-Ga Alloys:

Inelastic Neutron Scattering Measurements,” Phys. Rev. B 75 (5),

052406 (2007).

Zeisler, R., “Standard Sediment Supplied for Solid Sampling,” Trends

Anal. Chem. 25 (8), vi (2006).

Zeisler, R., Murphy, K.E., Becker, D.A., Davis, W.C., Kelly, W.R., Long,

S.E., Sieber, J.R., “Standard Reference Materials® (SRMs) for

Measurement of Inorganic Environmental Contaminants,” Anal

Bioanal. Chem. 386 (4), 1137 (2006).

Zhang, Q., Liu, G.Y., Rao, G.H., “Determination of Antisite Defects in

Double Perovskite Sr2FeMoO6 by Diffraction Method: Simulation

Studies,” Solid State Commun. 138 (6), 294 (2006).

Zhang, Q., Rao, G.H., Huang, Q., Feng, X.M., Ouyang, Z.W., Liu, G.Y.,

Toby, B.H., Liang, J.K., “Selective Substitution of Vanadium for

Molybdenum in Sr2(Fe1-xVx)MoO6 Double Perovskites,” J. Solid

State Chem. 179 (8), 2458 (2006).

Zhao, L., Robinson, L., Paul, R.L., Greenberg, R.R., Miao, S.L.,

“Application of Cold Neutron Prompt-Gamma Activation Analysis

in Environmental Studies of Aquatic Plants,” J. Radioanal. Nucl.

Chem. 271 (3), 777 (2007).

Zhao, P., Dai, L., Cullen, J., Wuttig, M., “Magnetic and Elastic Properties

of Ni49.0Mn23.5­Ga27.5 Premartensite,” Met. Mater. Trans. A 38A (4

745 (2007).

Zhao, W., Golding, T.D., Littler, C.L., Dinan, J.H., Dura, J.A., Lindstrom,

R.M., “Diffusion of Selenium in Liquid-Phase Epitaxy-Grown

Hg0.78Cd0.22Te,” J. Electron. Mater., in press.

Zhao, X., Yu, G., Cho, Y.-C., Chabot-Couture, G., Barišié, N., Bourges,

P., Kaneko, N., Li, Y., Lu, L., Motoyama, E.M., Vajk, O.P., Greven,

M., “Crystal Growth and Characterization of the Model HighTemperature Superconductor HgBa2CuO4+δ,” Adv. Mater. 18 (24),

3243 (2006).

Zheludev, A., Garlea, V.O., Masuda, T., Manaka, H., Regnault, L.-P.,

Ressouche, E., Grenier, B., Chung, J.-H., Qiu, Y., Habicht, K.,

Kiefer, K., Boehm, M., “Dynamics of Quantum Spin Liquid and

Spin Solid Phases in IPA-CuCl3 Under Field,” Phys. Rev. B, in

press. (chrns)

Zhou, H.D., Wiebe, C.R., Jo, Y.J., Balicas, L., Qiu, Y., Copley, J.R.D.,

Ehlers, G., Fouquet, P., Gardner, J.S., “The Origin of Persistent

Spin Dynamics and Residual Entropy in the Stuffed Spin Ice

Ho2.3Ti1.7O7-δ,” J. Phys.: Condens. Matter, in press. (chrns)

Zhou, W., Yildirim, T., “Lattice Dynamics of Metal-Organic Frameworks:

Neutron Inelastic Scattering and First-Principles Calculations,”

Phys. Rev. B 74 (18), 180301 (2006).

Zhou, W., Yildirim, T., Durgun, E., Ciraci, S., “Hydrogen Absorption

Properties of Metal-Ethylene Complexes,” Phys. Rev. B, in press.

Zou, F., Furno, F., Fox, T., Schmalle, H.W., Berke, H., Eckert, J.,

Chowdhury, Z., Burger, P., “trans-W(Cmesityl)(dmpe)­2

Revealing a Highly Polar W-H Bond and H-Mobility in Liquid and

Solid State,” J. Amer. Chem. Soc. 129 (22), 7195 (2007). (chrns)

78
NCNR 2007 ACCOMPLISHMENTS AND OPPORTUNITIES

Instruments and Contacts

Instruments and Contacts: (name, tel. 301-975-xxxx, email)

High Resolution Powder Diffractometer (BT-1):

•	 Judy Stalick, 6223, judith.stalick@nist.gov

•	 Qing Huang, 6164, qing.huang@nist.gov

•	 Mark Green, 4297, mark.green@nist.gov

•	 Sarah Poulton, 8491, sarah.poulton@nist.gov

Residual Stress Diffractometer (BT-8):

•	 Thomas Gnaeupel-Herold, 5380, thomas.gnaeupelherold@nist.gov

30-m SANS Instrument (NG-7):

•	 Lionel Porcar, 5049, lionel.porcar@nist.gov

•	 Mark Laver, 2000, mark.laver@nist.gov

•	 Paul Butler, 2028, paul.butler@nist.gov

•	 Jeff Krzywon, 6650, jkrzywon@nist.gov

•	 John Barker, 6732, barker@nist.gov

30-m SANS Instrument (NG-3) (CHRNS):

•	 Boualem Hammouda, 3961, hammouda@nist.gov

•	 Steve Kline, 6243, steven.kline@nist.gov

•	 Susan Krueger, 6734, susan.krueger@nist.gov

•	 Cedric Gagnon, 2020, cedric.gagnon@nist.gov

•	 John Barker, 6732, barker@nist.gov

USANS, Perfect Crystal SANS (BT-5) (CHRNS):

•	 Andrew Jackson, 3146, andrew.jackson@nist.gov

•	 Paul Butler, 2028, paul.butler@nist.gov

•	 John Barker, 6732, barker@nist.gov

Reflectometer, Vertical Sample, Polarized Beam Option (NG-1):

•	 Brian Kirby, 8395, brian.kirby@nist.gov

•	 Julie Borchers, 6597, julie.borchers@nist.gov

•	 Chuck Majkrzak, 5251, cmajkrzak@nist.gov

AND/R, Advanced Neutron Diffractometer/Reflectometer 

(NG-1):

•	 Ella Mihailescu, 8327, ella.mihailescu@nist.gov

•	 Joe Dura, 6251, joseph.dura@nist.gov

Reflectometer, Horizontal Sample (NG-7):

•	 Sushil Satija, 5250, satija@nist.gov

•	 Bulent Akgun, 6469, bulent.akgun@nist.gov

Double-focusing Triple Axis Spectrometer (BT-7)

•	 Ying Chen, 6442, ying.chen@nist.gov

•	 Jiying Li, 4570, jiying.li@nist.gov

•	 Jeff Lynn, 6246, jeff.lynn@nist.gov

Triple-axis Spectrometer (BT-9):

•	 William Ratcliff, 4316, william.ratcliff@nist.gov

•	 Ross Erwin, 6245, rerwin@nist.gov

•	 Jeff Lynn, 6246, jeff.lynn@nist.gov

SPINS, Spin-polarized Triple-axis Spectrometer (NG-5) (CHRNS):

•	 Hye-Jung Kang, 4863, hye.kang@nist.gov

FANS, Filter-analyzer Neutron Spectrometer (BT-4):

•	 Terry Udovic, 6241, udovic@nist.gov

•	 Juscelino Leao, 8867, juscelino.leao@nist.gov

DCS, Disk-chopper Time-of-flight Spectrometer (NG-4) (CHRNS):

•	 John Copley, 5133, jcopley@nist.gov

•	 Yiming Qiu, 3274, yiming.qiu@nist.gov

•	 Craig Brown, 5134, craig.brown@nist.gov

HFBS, High-flux Backscattering Spectrometer (NG-2) (CHRNS):

•	 Antonio Faraone, 5254, antonio.faraone@nist.gov

•	 Tim Jenkins, 8396, timothy.jenkins@nist.gov

NSE, Neutron Spin Echo Spectrometer (NG-5) (CHRNS):

•	 Antonio Faraone, 5254, antonio.faraone@nist.gov

•	 Jason Gardner, 8391, jason.gardner@nist.gov

•	 Michi Nagao, 5505, michihiro.nagao@nist.gov

Cold Prompt-gamma Neutron Activation Analysis (NG-7):

•	 Rick Paul, 6287, rpaul@nist.gov

Thermal Prompt-gamma Neutron Activation Analysis (VT-5): 

•	 Liz Mackey, 5149, liz.mackey@nist.gov

Other Activation Analysis Facilities:

•	 Greg Downing, 3782, gregory.downing@nist.gov

Cold Neutron Depth Profiling (NG-1):

•	 Greg Downing, 3782, gregory.downing@nist.gov

Neutron Imaging Station (BT-2):

•	 Dave Jacobson, 6207, david.jacobson@nist.gov

•	 Dan Hussey, 6465, daniel.hussey@nist.gov

•	 Muhammad Arif, 6303, muhammad.arif@nist.gov

Neutron Interferometer (NG-7):

•	 Muhammad Arif, 6303, muhammad.arif@nist.gov

•	 Dave Jacobson, 6207, david.jacobson@nist.gov

•	 Dan Hussey, 6465, daniel.hussey@nist.gov

Fundamental Neutron Physics Station (NG-6): 

•	 NG-6M: Scott Dewey, 4843, mdewey@nist.gov

•	 NG-6U: Pieter Mumm, 8355, pieter.mumm@nist.gov

•	 NG-6: Jeff Nico, 4663, nico@nist.gov

Theory and Modeling:

•	 Norm Berk, 6224, nfb@nist.gov

•	 Joseph Curtis, 3959, joseph.curtis@nist.gov

•	 Taner Yildirim, 6228, taner@nist.gov

Sample Environment: 

•	 Juscelino Leao, 8867, juscelino.leao@nist.gov

•	 Dan Dender, 6225, dender@nist.gov

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