ON THE COVER

The inset shows an exploded view of welded aluminum components of the second-generation liquid hydrogen cold source to be installed during 2001. The

cold source, which slows down thermal neutrons, is the round object located

right-middle. Surrounding it is a vacuum jacket located just to the right and left of the cold source. The outer layer, exploded top and bottom and to the left,

is the vacuum shroud that is also shown standing vertically on the front cover. Cold neutrons emerge from the cap shown at the left into 8 guides carrying them to beam instruments. (See layout on p. 2.)
NCNR 2000

NIST

CENTER FOR

NEUTRON

RESEARCH

ACCOMPLISHMENTS

AND

OPPORTUNITIES

NIST Special Publication 962

J. Michael Rowe, Director

Ronald L. Cappelletti, Editor Linda K. Clutter, Assistant Editor

February 2001

U.S. DEPARTMENT OF COMMERCE

Donald L. Evans, Secretary

Technology Administration Karen H. Brown, Acting Under Secretary of Commerce for Technology

National Institute of Standards and Technology

Karen H. Brown, Acting Director
DISCLAIMER

Certain commercial equipment, instruments, or materials are identified in this report to foster understanding. Such identification does not imply recommendation or endorsement by the National Institute of Standards and

Technology, nor does it imply that the materials or equipment identified are necessarily the best available for the purpose.

National Institute of Standards and Technology Special Publication 962

Natl. Inst. Stand. Technol. Spec. Publ. 962, 76 pages (February 2001) CODEN: NSPUE2

U.S. GOVERNMENT PRINTING OFFICE - WASHINGTON: 2001

For Sale by the Superintendent of Documents, U.S. Government Printing Office

Washington, DC 20402-9325

II
CONTENTS

FOREWORD iv INTRODUCTION 1 NCNR LAYOUT 2 NCNR IMAGES 2000 4 RESEARCH HIGHLIGHTS PHASE-CONTRAST IMAGING WITH NEUTRONS 6 FILTER-ANALYZER NEUTRON SPECTROMETER (FANS) 8 THE NCNR DISK CHOPPER TIME-OF-FLIGHT SPECTROMETER (DCS) 10 ULTRA-HIGH RESOLUTION SMALL-ANGLE NEUTRON SCATTERING (USANS) 12 LIGAND DYNAMICS IN Mn[N(CN)2]2.PYRAZINE 14 PROBING DISORDER IN CONFINED METHYL IODIDE 16 PRESSURE-INDUCED INTERLINKING OF CARBON NANOTUBES: COMPUTATIONS 18 DYNAMICS CHANGES IN THE MOLTEN GLOBULE-NATIVE FOLDING STEP 20 SOFT PHONON ANOMALIES IN RELAXOR FERROELECTRICS 22

LITHOSILICATES; A NEW FAMILY OF MICROPOROUS MATERIALS 24 QUANTIFICATION OF PHASE FRACTION AND AMORPHOUS CONTENT 26 DIFFRACTION ELASTIC CONSTANTS FOR ARBITRARY SPECIMEN AND CRYSTAL SYMMETRIES 28 DIRECT OBSERVATION OF SUPERHEATING AND SUPERCOOLING OF VORTEX MATTER 30 SANS MEASUREMENTS OF NANOSCALE LITHOGRAPHIC FEATURES 32 ASYMMETRIC MAGNETIZATION REVERSAL IN EXCHANGE-BIASED HETEROSTRUCTURES 34 THE ROLE OF THE CRP/CAMP PROTEIN COMPLEX IN DNA TRANSCRIPTION 36 POLYMER THIN FILMS UNDER SUPERCRITICAL CO, 38 COLD NEUTRON DEPTH PROFILING OF LITHIUM BATTERY MATERIALS 40 SERVING THE SCIENTIFIC AND TECHNOLOGICAL COMMUNITIES 42 THE NCNR USER PROGRAM 42 THE CENTER FOR HIGH RESOLUTION NEUTRON SCATTERING 42

SIXTH ANNUAL SUMMER SCHOOL 42 COLLABORATIONS 42 INDEPENDENT PROGRAMS 42 REACTOR OPERATION AND ENGINEERING 46 INSTRUMENTATION DEVELOPMENTS 47 RESEARCH TITLES 50 MATERIALS SCIENCE/CRYSTALLOGRAPHY 50 FORMERS 52 COMPLEX FLUIDS 53 CONDENSED MATTER PHYSICS 53 BIOMOLECULAR SCIENCE 56 CHEMICAL PHYSICS OF MATERIALS 57 INSTRUMENTATION 58 NEUTRON PHYSICS 58 MATERIALS ANALYSIS 60

AFFILIATIONS 61 PUBLICATIONS 62 INSTRUMENTS AND CONTACTS 72 CONTACTS Inside Back Cover

NiST CENTER FOR NEUTRON RESEARCH iii
FOREWORD

Once again, it is a pleasure to be able to reflect on the accomplishments of the NIST Center for Neutron Research over the

past year. The reactor shim control arms were replaced during a planned shutdown early in 2000. As a result, the reactor was scheduled to operate for 212 days during the reporting period, and did

operate 198 days, or 93 % of the scheduled time, as a consequence

of one unplanned maintenance shutdown. Construction was begun on

the new cooling tower which will not only provide needed capability

for the next 25 years, but will also reduce the plume visibility during

cold weather. The cold source availability for the period was 98 %;

i.e., the cold source held the reactor from operation 4 days during the

year. The second-generation liquid hydrogen cold source passed all

required pressure tests, and the final assembly is now being prepared

for insertion into the reactor in 2001. Finally, steady progress has been made in preparing for a license renewal application to the Nuclear Regulatory Commission, in order to extend the period of

operation beyond 2004. Three high-resolution inelastic scattering instruments, the High Flux Backscattering Spectrometer, the Disk Chopper time-offlight Spectrometer, and the Neutron Spin Echo spectrometer (highhghted in the 1999 report), are now being offered to users who

can tolerate the quirks inherent in getting a new instrument on-line. USANS, the perfect crystal small angle scattering spectrometer (part

of the NSF/NIST CHRNS), is installed at the reactor and available

for proposals; the first phase of the high intensity Filter Analyzer Neutron Spectrometer is operating with high intensity and good

backgrounds; and the design and manufacture of new thermal neutron spectrometers is underway. (USANS, DCS, and FANS are highlighted in this report.) This simultaneous development program has

put severe strains on our resources, but we can now look forward

to many years of benefit from the results. During the past year, a

proposal was made to the National Science Foundation (NSF) to

allow joint NIST/NSF operation of the three high-resolution instruments, and to construct a new cold neutron triple axis spectrometer.

The final disposition of this application is not yet available, but the

external reviews are complete, a site visit has taken place, and the NSF is now considering the appropriate action. If this proposal is

funded, then we will be able to operate these new inelastic scattering

instruments properly in a full user mode.

Finally, as always, the results are seen in the output of the

researchers who use the facility. As has become our practice, we

are presenting highlights of this work in the following chapters of

this report. I think that all can agree that the results truly speak for

themselves.

iv
INTRODUCTION TO

THE NIST CENTER FOR

NEUTRON RESEARCH (NCNR)

Modem technological society is dependent upon increasingly

sophisticated use of materials, many of whose attributes are

dictated by their sub-microscopic structural and dynamical properties. A wide range of scientific techniques, of which the many types of scattering (for example, x-rays, light, electrons, neutrons) are arguably the most important, provide knowledge of these properties.

Of these probes, neutrons are perhaps least famiUar, but they provide

important advantages for many types of measurements.

Neutrons, as prepared for use at modem sources, are moving

at speeds comparable to those of atoms moving at room temperature,

thus providing the ability to probe dynamical behavior. At the same

time, neutrons are well matched to measurements at length scales ranging from the distances between atoms to the size of biological

or polymer macromolecules. Neutrons are sensitive to the magnetic

properties of atoms and molecules, allowing study of the underlying

magnetic properties of materials. They also scatter quite differently

from normal hydrogen atoms than they do from heavy hydrogen

V (deuterium), allowing selective study of individual regions of molecular systems. Finally, neutrons interact only weakly with materials,

providing the opportunity to study samples in different environments more easily (at high pressures, in shear, in reaction vessels, etc.), and

making them a non-destmctive probe. These favorable properties are

offset by the relative weakness of the best neutron sources compared

to x-ray or electron sources, and by the relatively large facilities

required to produce neutrons. As a result, major neutron sources

are operated as national user facilities to which researchers come

from all over the United States (and abroad) to perform small-scale

science using the special measurement capabilities provided.

In addition to scattering measurements, neutrons can be used

to probe the atomic composition of materials by means of capture

and resultant radioactive decay. The characteristics of the decay act

as "fingerprints" for particular atomic nuclei, allowing studies of

environmental samples for pollutants (e.g., heavy metals), characterization of Standard Reference Materials, and many other essential measurements. While the scattering and capture users of neutrons

are little concemed with understanding the inherent properties of the

neutron, there are important areas in physics that can be explored

by carefully measuring fundamental neutron behavior. Examples

include the lifetime of the free neutron, an important quantity in the

theory of astrophysics; the beta decay process of the neutron, the

details of which are stringent tests of nuclear theory; and the effects

of various external influences such as gravity or magnetic fields on

neutrons. The NCNR utilizes neutrons produced by the 20 MW NIST

Research Reactor to provide facilities, including the Nation's only

internationally competitive cold neutron facility, for all of the above

types of measurements to a national user community. There are approximately 35 stations in the reactor and its associated beams

that can provide neutrons for experiments. At the present time 27

of these are in active use, of which 6 provide high neutron flux

positions in the reactor for irradiation, and 21 are beam facilities. A schematic layout of the beam facilities and brief descriptions of

available instmmentation are given below. More complete descriptions can be found at http://www.ncnr.nist.gov.

These facilities are operated both to serve NIST mission needs and as a national facility, with many different modes of access. Some

instrumentation was built years ago, and is not suited to general

user access; however, time is available for collaborative research. NIST has recently built new instrumentation (see the highlights in

this report on FANS, DCS, and USANS), and reserves 1/3 of available time for mission needs with the balance available to general

users. In other cases, instrumentation was built and is operated by

Participating Research Teams (PRT); PRT members have access

to 75 % of available time, with the balance available to general

users. In a special case, NIST and the National Science Foundation

established the Center for High Resolution Neutron Scattering at the NCNR, with a 30 m Small Angle Scattering (SANS) instrument,

a cold neutron triple axis spectrometer, and the thermal neutron

perfect crystal SANS commissioned this year. For these facilities, most time is available for general users. While most access is for

research, whose results are freely available to the general public,

proprietary research can be performed under full cost recovery. Each

year, approximately 1600 researchers (persons who participated in

experiments at the facility, but did not necessarily come here) from

all areas of the country, from industry, academe, and government use

the facility for measurements not otherwise possible. The research

covers a broad spectmm of disciphnes, including chemistry, physics,

biology, materials science, and engineering.

NIST CENTER FOR NEUTRON RESEARCH 1
NIST CENTER FOR NEUTRON RESEARCH LAYOUT

11

1 A Cold Neutron Depth Profiling instrument (not stiown) for quantitative profiling of subsurface innpurities currently at

tfiis site will be moved to another position. Shown is a proposed Triple Axis Cold Neutron Crystal Spectrometer

. 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.

2 BT-7 Triple Axis Spectrometer

with fixed incident energy for measurements of excitations and structure.

3 BT-8 Residual Stress Diffractometer optimized for depth profiling of residual

stress in large components.

4 BT-g Triple Axis Crystal

Spectrometer for measure- ments of excitations and structure.

5 Thermal Column A very well- thermalized beam of neutrons used for radiography, tomography, dosimetry and other experiments.

6 BT-1 Powder Diffractometer Powder diffractometer with 32

detectors; incident wavelengths

of 0.208 nm, 0.154 nm, and

0.159 nm, with highest resolution of 5d/d-8x10-r

BT-2 Triple Axis Crystal

Spectrometer with polarized

beam capability for measure- ment of magnetic dynamics and

structure. BT-4 Filter Analyzer

Spectrometer with cooled

Be/Graphite filter analyzer for chemical spectroscopy. BT-5 Perfect Crystal

Diffractometer SANS small angle neutron scattering instru- ment for microstructure on

the 10" nm length scale sponsored by the National Science Foundation and NIST, part of the Center for High Resolution Neutron Scattering (CHRNS).

10 NG-7 Horizontal Sample

Reflectometer allows

reflectivity measurements of free surfaces, liquid vapor

interfaces, as well as polymer

coatings.

11 Neutron Interferometry and

Optics Station with perfect

silicon interferometer; vibration

isolation system provides

exceptional phase stability and

fringe visibility. 12 Spin Polarized Triple Axis

Spectrometer (SPINS) using

cold neutrons with position

sensitive detector capability for high resolution studies, part of CHRNS.

2
21 20

15

13 Spin Echo Spectrometer offer- ing neV energy resolution, based upon Julich design,

sponsored by NIST, Julich and

ExxonMobil. 14 Prompt Gamma Activation Analysis cold neutron fluxes allow detection limit for H of

1 |ig to 10 p.g. Focused beams

are available for profiling. 15NG-7 30 m SANS for microstructure measurements sponsored by NIST, ExxonMobil, and

the University of Minnesota. 16 Neutron Pliysics Station a cola neutron beam 150 mm x 60 mm, available for fundamental

neutron physics experiments.

17 Fermi CtiopperTOF

Spectrometer a hybrid time-offlight spectrometer for inelastic scattering with incident wavelengths between 0.23 nm and

0.61 nm chosen by focusing

pyrolytic graphite crystals. A

simple Fermi chopper pulses

the beam. 18Disl( Ctiopper TOP

Spectrometer versatile fimeof-flight spectrometer, with beam pulsing and monochromatization effected by 7 disk choppers. Used for studies

of dynamics in condensed matter, including macromolecular

systems.

19NG-3 30 m SANS for microstructure measurements sponsored by the National Science Foundation and NIST; part of CHRNS.

20 Bacl(scattering Spectrometer:

high intensity inelastic scattering instrument with energy

resolution < 1 laeV, for studies

of motion in molecular and

biological systems.

21 8 m SANS for polymer characterization, sponsored by NIST

Polymers Division.

22 Vertical Sample

Reflectometers: instruments

for measuring reflectivities down to lO^to determine subsurface structure, with polarization analysis capability. No. 23

is a proposed instru-ment opti- mized for biological measurements.

NIST CENTER FOR NEUTRON RESEARCH 3
NCNR IMAGES 2000

Right: NCNR, cross-country skier's view. Below: Susliil Satija (NCNR) empliasizes a

point about reflectometry to participants in the 6th annual summer school on neutron

scattering held June 5-9, 2000.

Above: Jeremy Cook (NCNR) at the control

station of the Disk Chopper Spectrometer, which is highlighted in this issue. Left: Uta Dieregsweiler and Judith Wolk (U. Kiiln) measuring scattering from aerosols at the NG-7 30 m SANS.

Right: Rob Dimeo (NCNR) examines the

cryostat jacket Inside the chamber of the backscattering spectrometer. Arrayed on Debye-Scherrer rings behind him are Si (111) analyzer crystals.

4
Above: R. St. John Manley (McGill U.) and

NIST Polymer Division's David VanderHart and John Barnes discuss the significance

of the diffraction pattern at the NG-1 8 m

SANS. Right: Qingzhen Huang (U. Md.), Jeff Lynn (NCNR), and Eduardo da Silva-Granado

(U. Md.) strike

a pose while measuring

a magnetic structure at the BT-2 triple axis spectrometer.

NIST CENTER FOR NEUTRON RESEARCH 5
PHASE-CONTRAST IMAGING WITH NEUTRONS

Horizontal

scale 1 m

source

2D detector

position 1

Sample 1

Cold neutron beam

Neutrons from point y

Contact image

2D detector

position 2

Phase contrast image

FIGURE 1. Experimental layout.

In-line phase-contrast images have been observed with many

forms of radiation. Here we demonstrate that such images can be observed very simply with neutrons as well. Measurement of

the phase of a neutron wave conventionally requires a delicate

setup, carefully reducing interference-destroying vibrations of the

parts through which the beam passes. Here we describe an alternative method that only requires measurements of intensity to extract

phase infoiTnation, and thus bypasses the need for the precise setup

used in a conventional interferometric measurement. A schematic of the setup used for the present experiment

is shown in Fig. 1 . To give them the required transverse coherence,

monochromatic neutrons pass through a pinhole onto the sample. A

2-D CCD-type neutron camera then records the transmitted beam

intensity through the sample at some distance from it (plane 2 in

Fig. 1.) This downstream image is called the "phase-contrast image"

because it is enhanced by Fresnel diffraction, since interference due to phase differences corresponding to edge effects has had a chance to develop. The radiographic image recorded immediately

after the sample (plane 1 in Fig. 1) is called the "contact image,"

and essentially contains a shadow of the object.

The contact and phase-contrast images of the bullet-shaped

lead sinker, aligned with its axis perpendicular to the beam, taken

with a 0.433 nm beam at the NCNR interferometer beam line NG-7

are shown in Figs. 2a and 2b. These are direct images, corrected

only for the empty beam profile. In the normal radiograph (Fig. 2a)

the extent and internal details of the sample structure are not clearly

visible because of very low scattering and absorption. However, in

Fig. 2b interference has enhanced the image intensity contrast at the

edges of the sample and at boundaries within the imperfections at

the tip, rendering them clearly visible. Contact and phase contrast images of a wasp are shown in Figs. 2c and 2d, respectively. Notice

that in the phase-contrast image all the delicate and thin organs of

the wasp, e.g., antennae, leg segments, and wings, become visible.

Since this method is so simple, many applications investigating

internal features not otherwise visible are now possible.

Turning attention now to extracting phase information, after

the beam has passed through the sample, particularly for an object

offering little absorption or scattering, refractive variations within

the sample still cause the beam's phase to be modulated. As a result,

the radiation intensity transverse to the direction of propagation

is redistributed. By measuring these intensity changes alone one

can retrieve the phase density profile of the sample without using

an interferometer. The mathematical basis for this phase retrieval

FIGURE 2. (a) contact and (b) phase contrast images of a lead sinker shown

between them, (c) contact and (d) phase contrast images of a wasp.
D.L. Jacobson, M. Arif and S.A. Werner

Physics Laboratory

Ionizing Radiation Division

National Institute of Standards and Technology

Gaithersburg, MD 20899-8461

B.E. Allman, P.J. McMahon, K.A. Nugent, and D. Paganin

School of Physics The University of Melbourne

Victoria 3010, Australia

technique is based on the quantum mechanical analogue of the socalled "Transport of Intensity Equation (TIE)" of a wave

\/lir[, <:)exp(i0(r^, z))exp(/27Cz//l), with irradiance, /(r^, z) and

phase (f){r[, z) transverse to the beam [1, 2]:

27t dlirl, 0) A dz = -V,.[/(r^.O)V,(^(r^,0)] (1).

The TIE allows one to make a quantitative determination of the phase because the intensity of the propagated wave in a

given transverse plane downstream is dependent on the intensity and

phase upstream [3]. This technique is well developed for x-rays and

electrons. Very beautiful experiments have been performed using both of these radiation types [4,5,6]. We recently carried out a series of experiments [7], for the

first time with neutrons, to measure the phase modulated intensity

changes caused by a sample and to quantify the observed phase

profile using this technique. The experiments were performed at NG-7 and also at NG-0. NG-0 is a curved neutron guide providing

a polychromatic neutron beam with the Maxwellian peak centered around 0.432 nm. At the NG-7 guide a PG(002) crystal was used to

extract a beam in the range of 0.235 nm to 0.475 nm.

Both contact and phase-contrast images were recorded in

order to obtain the derivative on the left side of Equation (1). The

phase-contrast image was taken with the CCD placed 1.5 m to

1.8 m from the sample. The images from the CCD are downloaded

to a computer and the centroids of the neutron events are determined by hardware processing, achieving a best-case resolution of about 60 [xm.

Figure 3a shows an image constructed from such an analysis of the lead sinker (of Fig. 2) whose longitudinal axis is nearly

aligned with the incident beam. In Fig. 3b is plotted a profile of

the retrieved phase along AB (blue curve). This profile was obtained through Fourier processing of the data. The predicted phase profile

(dotted curve) determined from the sample geometry and orientation

is in excellent quantitative agreement with the experimental data. This phase retrieval technique works with a polychromatic

beam and is not constrained by low flux. We plan to extend both of

these types of measurements using polarized and very cold neutrons

to study magnetic domain structures, interface boundaries and density variations in multi-layer thin films. We also plan to carry out tomographic measurements in the near future. REFERENCES

[I] M.R. league, J.Opt.Soc.Am. 73, 1434(1983).

[2] T. E. Gureyev, A. Roberts, and K. A. Nugent, J. Opt. Soc. Am. A 12, 1942 (1995).

[3] D. Paganin and K.A. Nugent, Phys. Rev. Lett. 80, 2586 (1998).

[4] A. Barty, K. A. Nugent, D. Paganin, and A. Roberts, Opt. Lett. 23, 817 (1998).

[5] B. E. Allman, R J. McMahon, J. B. Tiller, K. A. Nugent, D. Paganin. A. Barty, L

McNulty, S. R Frigo, S. Wang, and C.C. Retsch, J.Opt. Soc. Am A 17, 1732 (2000).

[6] K. A. Nugent, T. E. Gureyev, D. Cookson, D. Paganin, and Z. Barnea, Phys. Rev.

Lett. 77, 2961 (1996).

[7] B. E. Allman, P. J. McMahon, K. A. Nugent, D. Paganin. D. L. Jacobson. M. Arif, and S. A. Werner, Nature 408, 158 (2000).

2,400

FIGURE 3. a) reconstructed image of lead sinker along beam direction; b) measured (blue) and computed (dotted) phase

variations along line AB in a). NiST CENTER FOR NEUTRON RESEARCH
FILTER-ANALYZER NEUTRON SPECTROMETER (FANS)

Neutron vibrational spectroscopy (NVS) is an invaluable technique for probing vibrational dynamics. In particular, the typical range of energies accessible with reactor-based neutrons spans

the region of important lattice and molecular vibrations. Moreover,

the unique nature of the neutron-nucleus interaction permits the

observation of all vibrational modes in an NVS experiment, not just

those that satisfy appropriate symmetry-based selection rules as in photon spectroscopies. NVS is particularly useful for characterizing

hydrogenous materials since the incoherent scattering cross section

for hydrogen is much larger than for virtually all the other elements. Over the past twenty years, neutron vibrational spectra have

been collected for a broad array of both hydrogenous and non- hydrogenous systems utilizing a first-generation Filter-Analyzer Neutron Spectrometer (FANS) located at BT-4. Although this instru- ment possessed an excellent signal/noise ratio, the measured scattering intensities were limited by a relatively small detector solid

angle. Moreover, the BT-4 beam time was typically shared with a

triple-axis instrument. A second-generation FANS is currently being

constructed at BT-4 in two phases in order to obtain a dedicated

FANS spectrometer with an enhanced measurement sensitivity of

about two orders of magnitude. This instrument will ultimately overcome the classic objections to NVS, namely the requirement

for much larger samples and longer counting times than are typical of infrared and Raman spectroscopies. Phase I of this second-generation instrument (FANS-I) is now complete, yielding a twenty-fold

increase in sensitivity with another factor of at least five anticipated

upon completion of phase II.

Figure I illustrates the FANS layout. Using either a Cu(220)

or pyrolitic graphite (PG) (002) monochromator covers an accessible

FIGURE 2. Comparison of the larger phase-l and original FANS detector banks.

Beam Stop

Detectors

Shielding FANS-I configuration

Original configuration

oo

o

35 40 45 50 55 60 65 70 75

Neutron Energy Loss (meV)

FIGURE 1. Schematic diagram of the final configuration of FANS. Presently

installed phase I includes the filters to the right of the beam.

FIGURE 3. Comparison of the neutron vibrational spectrum for triethylene diamine (CjHjjjNj measured with FANS-I vs. that measured with the original configuration.

8 RESEARCH HIGHLiQHTS
D. A. Neumann and T. J. Udovic P. Papanek

NIST Center for Neutron Researcti NIST Center for Neutron Researchi National Institute of Standards and Technology National Institute of Standards and Technology

Gaithersburg, MD 20899-8562 Gaithersburg, MD 20899-8562

and

Department of IVlaterials Science and Engineering

University of Pennsylvania

Philadelphia, PA 19104

energy range of ^ 5 me\' to 250 meV with options for precollimations of 60'. 40', or 20' and postcollimations of 40', 20', or 10'. The intensity improvement of the phase-I instrument is due to the

twenty-fold increase in detector solid angle provided by a much

larger detector bank (see Fig. 2). The accompanying analyzer filter

consists of a Be-PG-Be layered arrangement cooled with hquid

nitrogen to enhance transmission of the low energy neutrons. Such

a low-bandpass filter provides a best resolution at the lowest energy

transfers of 1.1 meV FWHM.

The first measurements during the spring of 2000 confirmed

the magnitude of the expected gains. For example, Fig. 3 displays

the low-temperature neutron vibrational spectrum for triethylene

diamine measured using the new FANS-I configuration compared

with that measured using the original configuration under identical beam coUimations and measurement times. This gain in intensity is accompanied by a somewhat improved signal/noise ratio. The enhanced capabilities of the FANS-I instrument have

already been demonstrated for a variety of materials including protonic conductors, organic solids, metal hydrides, carbon nanotubes,

and metal oxides. These experiments confirmed substantial reductions in required sample size and/or measurement time. For examFIGURE 4. Temperature dependence of the NV spectrum of RbHCSOJg s^lSeOJg^g. (Data collected by T. Yildirim, NCNR.)

M. L. Klein A. K. Cheetham

Department of Chemistry IVlaterials Department

University of Pennsylvania University of California at Santa Barbara

Philadelphia, PA 19103 Santa Barbara, CA 93106

J. E. Fischer

Department of Materials Science and Engineering

University of Pennsylvania

Philadelphia, PA 19104

pie, Fig. 4 displays the temperature dependence of the NV spectrum

for RbH(S04)Q g|(Se04)o a protonic conductor oxide with lattice

protons that become mobile at temperatures less than 473 K.

Vibrational spectra were collected with FANS-I at nine different

temperatures in less than one day, a feat not possible using the

original instrument. It proved particularly interesting that the energy

of the mode near 100 meV decreases while that of the mode near 83 meV increases with increases in temperature concomitant with rapid

decreases in both peak intensities. Indeed, these proton-related features largely disappear at temperatures as low as 200 K, indicating

that there is significant proton motion even at this low temperature.

Figure 5 shows the FANS-I spectrum for solid 3-nitrophenol

[HOCCgHJNO,] compared with a GAUSSIAN calculation for the

isolated molecule. This spectrum exemplifies the overall quality and

high-resolution capabilities enabled by the marked improvement in

sensitivity. There is fair agreement between calculation and experi- ment for many features in the vibrational density of states, although

it is clear that significant intermolecular hydrogen bonding interactions in the solid cause strong perturbations in the OH wagging

mode predicted near 45 meV for the isolated molecule.

20 40 60 80 100 120 140 160

Neutron Energy Loss (meV)

FIGURE 5. NV spectrum for solid 3-nitrophenol [HOiCeHJNOj] at 10 K compared

with a GAUSSIAN calculation (b3lyp/6-316*) for the isolated molecule.

(Data collected by T. Heilweil, NIST Physics Laboratory, and C. M. Brown, U. Md.and NCNR.)

NIST CENTER FOR NEUTRON RESEARCH 9
THE NCNR DISK CHOPPER TIME-OF-FLIGHT

SPECTROMETER (DCS)

The recently commissioned Disk Cliopper Spectrometer (DCS)

is a versatile state-of-the-art instrument that is primarily intend- ed for studies of diffusional processes and low energy excitations in

materials. It has no equal in North America and is fully competitive

with comparable instruments in Europe.

The spectrometer is shown schematically in Fig. 1 . Following

a tapered offset guide assembly ("neutron optical filter") that removes almost all of the 7-rays and high energy neutrons from

the reactor beam [1], seven phased disk choppers supply monochromatic bursts of neutrons at the sample position. Three parallel banks

of 6 atmosphere ""He detectors, of 400 mm active length, are placed

4010 mm from the sample position, and ^ 90 % of the space between the sample and the detectors is argon-filled. Each of the 913

rectangular cross section detectors subtends 0.5° in the scattering

plane. The central bank provides continuous angular coverage from

-30° to -5° and from 5° to 140°. The overall detector coverage is ^ 0.65 sr, double that of the INS spectrometer at the Institut Laue

Langevin, Grenoble. Presently fitted with a 50 mm long room

temperature beryllium filter, the instrument operates at wavelengths

greater than ^ 4.1 A. The beryllium will shortly be replaced with an assembly of cold oriented graphite, 100 mm in length, permitting measurements down to =^ 2.3 A. (Wavelengths near 3.33 A and 6.67 A will be unavailable.) The first two and last two choppers are fitted

with three slots of different widths, enabling a choice among three

"resolution modes" at a given wavelength and master chopper speed.

The neutron current density at the sample and the energy resolution width at the detectors are shown in Figs. 2 and 3 respectively.

In designing and building the DCS, great care has been taken to

ensure that distances and detector locations are accurately known.

The stability of the chopper phasing results in a resolution hneshape

with a sharp leading edge. The sample area is easily accessed at beam level and from above. The data acquisition system has been

carefully designed and is extremely reUable. We plan to modify it

so that crude pulse height spectra can be extracted. The software

is user-friendly and will be improved as time permits. Planned

improvements, apart from the crystal filter replacement, include removal of the two innermost reflecting plates within the guides

after the first chopper; this will increase the flux with little reduction

in versatility. With the new cold source and these optics improve- ments we anticipate a threefold improvement in flux within the next

year. The first officially approved experiment using the DCS was

a comparative study [2] of native bovine -lactalbumin (BLA) and

-lactalbumin in a "molten globular" state (MBLA); the latter state

is partially folded and compact, with native-like secondary structure

but lacking the side-chain packing that characterizes the native state. Molten globules play an important role in understanding protein

folding mechanisms, and molten globules also participate in important cellular functions. The DCS measurements (Fig. 4) confirm and

extend previous results [3, and see also the article by Z. Bu et al. on

Confinement

Building (C100)

Cold source j

0.25

Neutron Guide Hall (G1 00)

Guide width

30mm

Local shutter and

Crystal filter

26.8m

Choppers

Sample

position

Detectors

I I at 4.0m

I I

9.0m

I I

I I 1.5m

FIGURE 1. A schematic plan view of the DCS.

10 RESEARCH HIGHLIGHTS
John Copley Jeremy Cook Felix Altorfer NIST Center for Neutron Research NIST Center for Neutron Research Paul Scherrer Institut National Institute of Standards and Technology National Institute of Standards and Technology CH-5232 Villigen PSI Gaithersburg. MD 20899-8562 Gaithersburg, MD 20899-8562 Switzerland and

University of Maryland

College Parl(, MD 20742

p. 20 of this report] obtained with the Fermi chopper spectrometer

(PCS); the unproved energy resolution of the DCS adds confidence

to the earlier results, especially for BLA. The structural differences between BLA and MBLA are reflected in the dynamics on time

scales of order 10 ps to 100 ps. whereas complementary measure10^

E

o

.10'

CO

^10^

10^

• Low resolution mode

. Medium resolution mode

High resolution mode

4 6 8 Wavelength (A) 10 12

FIGURE 2. The neutron current density at the sample position with all choppers

spinning at 20 000 rpm. Measured values are shown for the three "resolution modes" of the instrument.

ments have shown that the high frequency dynamics are virtually

unchanged.

The moniker "boson peak" has of late been associated with

an excess feature that shows up in the vibrational density of states

of many materials, generally in the Debye region, between 1 meV

and 10 meV. While the molecular origin of the peak is unclear,

its characteristic energy suggests that it is a collective excitation between the low energy acoustic modes and localized high energy

optic modes (representing local bond vibrations, librations, bendings, etc.). In a recent experiment [4] the thermal softening of the boson peak was studied in detail in a polyester carbonate copolymer

that had already been extensively studied using the FCS and the NCNR backscattering spectrometer. The DCS is particularly well

suited for such a study because of the large solid angle of detectors and the large beam size. The analysis of the data is in progress. Other materials recently studied using the DCS include car- bon nanotubes and superionic proton conductors. REFERENCES

[1] J.R.D. Copley, J. Neutron Res. 2, 95 (1994).

[2] Z. Bu et ai, private communication.

[3] Z. Bu, D. A. Neumann, S.-H. Lee, C. M. Brown, D. M. Engelman, and C. C. Han,

J. Mol. Biol. 301, 525 (2000).

[4] C. Soles et al. private communication.

300

200

100

0

>BLAatFCS

BLA at DCS

MBLA at DCS

* ^ T \ ^_ ^

6 i o It-^ o

Oq "o

I I I . I

: L

Wavelength (A)

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4 .0

FIGURE 3. Calculated resolution widths (full widths at half maximum height)

for the three "resolution modes" of the instrument. Some experimental widths

are also shown.

FIGURE 4. The Q dependence of the full-width at half maximum height of the

quasielastic Lorentzian peak for native bovine a-lactalbumin (BLA) and for molten globular bovine a-lactalbumin (MBLA) in 8M urea [2]. Results [3] for BLA from the Fermi chopper spectrometer (FCS) are shown for comparison.

NIST CENTER FOR NEUTRON RESEARCH
ULTRA-HIGH RESOLUTION SMALL-ANGLE

NEUTRON SCATTERING (USANS)

A

perfect crystal diffractometer (PCD), shown in Fig.l, for ultrahigh resolution small-angle neutron scattering (USANS) measurements is now in operation at the thermal neutron beam port,

BT-5. The PCD increases the maximum size of features accessible

with the NCNR's 30 m long, pinhole collimation SANS instruments by nearly two orders of magnitude, from 10- nm to 10* nm. The PCD is a Bonse-Hart type instrument with large triplebounce, channel-cut Si (220) crystals as monochromator and analyzer. The perfect crystals provide high angular resolution while

the multiple reflections suppress the "wings" of the beam profile, improving the signal-to-noise ratio to values comparable to that

obtained with pinhole instruments. This technique, widely utilized

for x-rays for many years, has only recently been successfully adapted for neutrons [1] as dynamical diffraction effects arising from the deep penetration of neutrons in thick perfect ciystals have become

better understood. Neutrons can, in effect, propagate through a thick

crystal, and then reflect from the back-face of the crystal. The

geometry of this second diffraction path allows part of the beam to bypass the second and third reflections. The design of the NCNR's

PCD [2] successfully eliminates the single reflection path by adding

shielding along the middle of the long face of each crystal between

the first and third reflections (see inset in

Fig. 2). The additional shielding reduces the wings in the rocking curve by two orders

of magnitude, resulting in a signal-to-noise

ratio of 10' at a minimum scattering vector Q = 0.0005 nm '. Figure 2 shows typical

rocking curves with and without shielding

of the deleterious back-face reflection. The beam flux obtained

for smaller samples is 3000 cm -s ', while the maximum intensity

obtained is 15 000 s-' when using the maximum 3x5 cm- beam

size. The mainly fast neutron flat background («= 0.15 s ') found at

large angles is independent of beam size. The beam intensity will

increase somewhat when the present perfect crystals are replaced by

ones with a wider channel, and a gap in the middle of the long face,

in order to increase the beam width to 4 cm with no contamination

from single back-face reflections. The measurement range of the PCD overlaps that of the NCNR's 30 m SANS instruments. Together they probe structure

in materials over four orders of magnitude, from =«1 nm to 10"*

nm. Combined measurements on these instruments will enable fuller

characterization of hierarchical and highly anisotropic microstructures in materials, for example in fiber or clay impregnated nanocomposites. The PCD is part of the NIST/NSF Center for High

Resolution Neutron Scattering (CHRNS) with up to two-thirds of

the available beam time to be allocated by the NCNR's Program

Advisory Committee to scientists and engineers who submit proposals for peer review. The PCD USANS instrument can accept any ancilliary samFIGURE 1. NCNR's Derek Ho (top) and John Barker load a sample at the PCD. The triple-bounce analyzer is visible in the center foreground of the picture.

12 RESEARCH HIGHLIGHTS
J. G. Barker and C. J. Glinka

NIST Center for Neutron Researcti National Institute of Standards and Technology

Gaithersburg, MD 20889-8562

10"

- 10

a

S£ 10'

1 10' o

o

10-^ r

10"

-3x10"' -2x10"' -1x10"' 0 Q (A-^:1x10"' 2x10-' 3x10"'

FIGURE 2. Rocking curves measured for tlie PCD USANS instrument. The diamond symbols are data taken before adding

shielding to block back-face reflections from the triple-bounce, channel-cut monochromator and analyzer crystals. The

circle symbols are data taken after adding such shielding. The dash-dot curve is the theoretical profile for a pair of triple-bounce perfect crystals. The solid line is the weighted sum of the theoretical profiles for 3x3 and 1x1 rocking

curves, with weighting factors of 0.998 and 0.002, respectively. The inset shows a schematic diagram of a channel-cut

crystal with the shielding needed to remove the single reflection path from the back-face of the crystal.

% 10'

aa

§ 10'

10

/Rg=920A !

; Porod: '

: X m=:-3

30 m SANS

^ \ res. limit

1

1 li 10" 10- 10- Q (AFIGURE 3. First USANS measurement obtained using new PCD instrument. The

sample is a 2.5 cm thick commercially obtained poly(tetrafluoroethylene) plate. Scattering is predominately from residual sub-micron size pores 0.2 % by volume) that survive the extrusion processing of the material.

pie environment equipment that is used on the 30 m SANS instruments. Larger liquid sample cells and a dedicated two-position heating block (30 °C to 400 °C) are currently being designed to utilize

the larger available beam size. The first USANS measurement was made in May 2000 on

a commercially obtained poly(tetrafluoroethylene) plate. The slit- smeared data are shown in Fig. 3. The data easily overlap the accessible Q-rmge the 30 m SANS instruments. Examples of material

systems studied so far are: pigment aggregation in paint, clay aggregation structures in various solutions and polymer melts, pores in

copper, hydrides in uranium, and large scale structures in controlled

pore glasses.

REFERENCES

[1] M. Agamalian, G.D. Wignall, R. Triolo, J. Appl. Cryst. 30, 345 (1997).

[2] A.R. Drews, J.G. Barker, C.J. Glinka, M. Agamalian, Physica B 241-243, 189 (1998).

NIST CENTER FOR NEUTRON RESEARCH 13
LIGAND DYNAMICS IN Mn[N(CN)2]2-PYRAZINE

One of the major themes of solid state chemistry is the develop- ment of new molecular architectures with novel chemical and

physical properties for applications such as chemical separation,

catalysis, and magnetic devices. Compounds consisting of transition

metal ions linked together by polydentate organic ligands are of

particular interest because their properties can be tailored by judicious choice of the components. For example, changing the transition metal can alter both the bonding motif and magnetic properties

of these systems. The properties of these materials can also be

controlled by introducing ancillary 7i-conjugated ligands such as

pyrazine (pyz), 4,4'-bipyridine and 2,2'-bipyridine. These molecular

building blocks not only affect the spatial separation of the transition metal cations and the dimensionality of the crystal, but also modulate the superexchange interactions. For instance, of the many

Mn[N(CN)2], L materials examined to date, only L - pyrazine exhibits long-range magnetic order above 2 K. The structure of Mn[N(CN)2]2.pyz can be described as an

inter-penetrating ReO^-like network with axially elongated Mn^*

octahedral and edges made-up of |i-bonded [N(CN)2]" anions and

neutral pyrazine ligands (Fig. 1) [1]. Upon heating above = 200

K, Rietveld refinements of neutron powder diffraction (NPD) data

indicate a marked increase in the Debye-Waller factor for the midnitrogen in the cyanamide ligand and a concomitant appearance of thermal diffuse scattering. Further heating to = 400 K results in a phase transition to an unknown structure. While the structural and magnetic behaviors of these materials have been rather well characterized, very little information has been obtained concerning the interactions that underlie the interesting bonding motifs. Due to its unique sensitivity to hydrogen and

the possibility of covering a wide range of timescales, neutron

spectroscopy is particularly well suited to probe ligand dynamics

that directly reflect the bonding interactions. Quasielastic neutron

scattering (QENS) provides information on the geometry and timescale of diffusive motions. For "localized" motions, the geometry is embodied in the elastic incoherent structure factor (EISF); the ratio

of the elastic scattering to the total scattered intensity. For all temperatures studied, a quasielastic signal due to the paramagnetic Mn-+ ions and the dynamics of the cyanamide ligand

FIGURE 1 . Crystal structure of Mii[N(CN)2]2-pyz showing the two Independent,

interpenetrating ReOj-IIke lattices. The hydrogen atoms of the pyrazine ring have been omitted, while the Mn, C, and N atoms are depicted as red, black, and blue spheres, respectively.

FIGURE 2. The experimental EISF (black circles) for Mn[N(CNy2-pyz at 425 K, has been corrected (blue circles) for coherent and paramagnetic quasielastic

scattering. The solid red line is a fit to the corrected data with a 2-fold jump

model that results in a proton jump distance of 4.17(1) A. For comparison, the expected EISF for proton diffusion on a circle is also shown (red dashed line).

14 RESEARCH HIGHLIGHTS
C. M. Brown

University Of Maryland

College Park, MD 20742

and NIST Center for Neutron Researcti National Institute of Standards and Teclinology

Gaittiersburg, MD 20899-8562

J. L. Manson

Material Science Division Argonne National Laboratory Argonne, IL 60439

D. A. Neumann

NIST Center for Neutron Research

National Institute of Standards and Tectinology

Gaithersburg, MD 20899-8562

J. W. Lynn

NIST Center for Neutron Research

National Institute of Standards and Technology

Gaithersburg, MD 20899-8562

J. S. Miller

Department of Chemistry

University Of Utah

Salt Lake City, UT 84112

was observed. However, above = 425 K, the quasielastic signal in

the pyrazine compound is significantly larger. Figure 2 shows the ^-dependence of the EISF for the protonated compound and the same data after subtracting the measured quasielastic scattering from

a deuterated material. These data are very well described by a twofold proton jump model where the only variable parameter, the jump

distance, is found to be 4.17(1) A, consistent with the analysis of the NPD data which gives the D-D distance across the pyrazine ring as = 4.16(2) A. Further, the width of the quasielastic peak is constant

over the entire 2-range, as expected for a simple, localized jump

motion (the correlation time is = 70 ps at 425 K). Thus, the pyrazine

Ugands must be performing 7i-jumps about the axis defined by the

coordinating nitrogens.

The phonon density of states for Mn[N(CN)2]2.pyz at selected

temperatures covering all structural phases is shown in Fig. 3. In

addition to the general broadening and softening of the spectral

features with temperature, the intense peak assigned to the libration

of the pyrazine ring at = 11.2 meV is strongly attenuated and,

assuming a two-fold cosine potential, suggests an activation energy

of = 1.2 eV. Because this activation energy is much larger than k^T

at the temperature where one observes fially dynamic pyrazines (425

K) and the quasielastic scattering appears abruptly at the structural

transition, the transition must result in a greatly reduced rotational

barrier. Unfortunately, the activation energy for this process was

not measurable due the proximity of the material's decomposition

temperature.

Vibrational spectra at higher energy transfers were recorded on the FANS spectrometer (Fig. 4). Our calculations agree well with

observation and show that the spectrum is dominated by the normal

modes of the hydrogen containing pyrazine. Current investigations

are aimed at understanding how the transition metal affects the dynamics of the ligands.

REFERENCES

[1] J. L. Manson, Q.-Z. Huang, J. W. Lynn, H.-J. Koo, M.-H. Whangbo, R. Bateman,

T. Otsulca, N. Wada, D. N. Argyriou, and J. S. Miller. Submitted to Journal of the American Chemical Society.

0.07 -

0.06 -

0.05 -

i>

CD 0.04 -

0.03 -

0.02 -

0.01 -

0.00*

20.0 30.0 40.0 Energy Transfer (meV)

2000.0

1500.0

oo

1000.0

500.0

0.0

FANS

Pyz fragment, LDA 631 G*

N(CN)2 frag. LDA 631 G*

25.0 50.0 75.0 100.0 125.0 150.0 Energy Transfer (meV)

FIGURE 3. Temperature dependence of the vibrational density of states of Mn[N(CN)j2-pyz measured on the FCS spectrometer at a wavelength of 4.8 A.

FIGURE 4. The vibrational spectrum (blue) of Mn[N(CN)2]2-pyz (10 K) measured on

the upgraded FANS spectrometer. Shown in red and green are the calculated

contributions from chemically simplified, isolated fragments of [Ca-pyz-Ca]'>^ and [Ca-NCNCN-Ca]'', respectively.

NiST CENTER FOR NEUTRON RESEARCH 15
PROBING DISORDER IN CONFINED METHYL IODIDE

The presence of structural disorder in many materials can have a

dramatic effect on macroscopic properties. Typically, structural

disorder is described in terms of molecular spatial distributions determined from diffraction measurements. A complementary view

is to quantify disorder by determining the distribution of potential

energies experienced by the molecules. For a highly ordered system

the distribution is sharp while it is broad for a disordered system.

To explore this approach, high-resolution neutron inelastic scattering

has been used to examine the low-energy rotational dynamics of

simple symmetric top molecules confined to extremely tiny pores.

In effect, the porous substrate furnishes a static impurity distributed

throughout the molecular solid that can be thought of as disorder quenched into the molecular matrix. The modification to the rotational spectrum of the confined molecules measured using neutron

scattering can then be related to the distribution of potential energies. This measurement technique, known as rotational tunneling

spectroscopy [1], is extremely sensitive to the environment experienced by the molecules. By modeling the observed spectra one can

quantitatively extract the potential energy distribution.

Rotational tunneling spectroscopy is rooted firmly in quantum

mechanics. In a simple picture the potential barrier to reorientation

Stochastic

reorientation

FIGURE 1 . Potential energy model for a CH, rotor showing the three types of low energy motions observable with neutrons. Note that each circle located in a potential minimum represents one of three particular orientations of the CH,

methyl group of the CH3I molecule depicted on the right.

that, to a good approximation, has three minima determines the motion of a methyl group (a pyramid with a base of three hydrogen

atoms having a carbon atom at its apex seen in Fig. 1). In the limit of a small barrier to reorientation, the methyl group can undergo

nearly free rotation about the C-I axis. In the limit of a very

high barrier, the methyl group can oscillate (librate) within minima.

When the temperature is high enough to provide sufficient kinetic

energy, the molecule can reorient stochastically by jumping over the

barrier, a process known as rotational diffusion. Some molecules

such as methyl iodide (CH3I) possess finite barriers in which the

rules of quantum mechanics allow the methyl group to reorient

via tunneling through the barrier. A schematic illustration of these

processes in terms of the potential energy is shown in Fig. 1. Measurements of the rotational tunneling of methyl iodide (CH3I) confined to a porous glass with a very narrow pore size

distribution (diam = 58 A) were performed using the NIST backscattering spectrometer very well suited to such measurements due to

its excellent energy resolution: bE (FWHM) < 1 |J.eV. Measurements

were carried out for the bulk soUd, partially filled pores, and completely filled pores. Spectra taken at 5 K are shown in Fig. 2.

-10 -5 0 5 10

E(|xeV)

FIGURE 2. Tunneling spectra for the bulk CH3I (solid red line), partially filled pores (blue squares), and completely filled pores (black circles). Bulk-like peaks (red arrows) indicate strong order while the broad peaks (blue arrows)

indicate that disorder is present.

16 RESEARCH HIGHLIGHTS
R.M.Dimeo and D.A.Neumann

NIST Center for Neutron Research

National Institute of Standards and Tecfinology

Gaittiersburg, MD 20899-8562

FIGURE 3. Origin of tlie asymmetric lineshape observed in confined CH3I. A FIGURE 4. The barrier beigbt probability density extracted from full pore tunnel- symmetric distribution of potential barriers yields an asymmetric tunneling ing spectra at 5 K. lineshape.

The bulk CH3I spectrum shows two sharp side peaks whose

positions are related to the frequency at which the methyl group

(CH3) tunnels between three equivalent orientations. The location of

these peaks is directly related to the potential barrier height hindering reorientation. These peaks at ± 2.5 p.eV correspond to a potential

barrier of 42 meV. When the pores are partially filled (50 %) a broad

set of peaks appear at ± 4 (ieV. In addition to these broad peaks, a broad featureless scattering intensity appears underneath the welldefined peaks over the entire dynamic range. When the pores are completely filled the broad peaks at ± 4 |ieV increase in intensity

and a new set of peaks at ± 2.5 [leV appear. We interpret these

different peaks as due to the presence of varying amounts of order in

the molecular structure of the confined CH3I. The narrow peaks that occur in the bulk and the full-pore spectra point to the similarity

of the potentials experienced by the molecules as expected when

there is structural order. The broad peaks at ± 4 |j.eV correspond to methyl groups under the influence of a distribution of potential barriers. The very broad scattering feature underlying both the full-pore

and partially-filled samples is attributed to very strongly disordered methyl groups. Based on the filling dependence of the two broad

scattering components, these are attributed to molecules near the

glass surface while the narrow peaks at ± 2.5 jieV are due to molecules located near the center of the pore. To quantify the disorder, we performed numerical calculations

of the effects of a distribution of potential barriers on the tunneling

hneshape. In Fig. 3 we plot the variation of the potential barrier as a

function of tunneling energy. For a broad but symmetric distribution

of barrier heights, the tunnehng lineshape is clearly asymmetric.

Finally, using a relationship between the tunneling energy and barrier height we may extract the probability density for a particular

barrier height, P{V^). The result for the full pore spectra corrected

for instrumental resolution is shown in Fig. 4. Thus neutron inelastic scattering measurements of the rotational tunnehng spectrum offer a means of quantifying the disorder

of the energy landscape in this system of molecules in a confined

geometry. A further challenge is to correlate the energy and structural descriptions of disorder. REFERENCES

[1] W. Press. Single-Particle Rotations in Molecular Crystals, Springer-Verlag, Berlin. Heidelberg, New York, (1981).

NIST CENTER FOR NEUTRON RESEARCH 17
PRESSURE-INDUCED INTERLINKING OF CARBON

NANOTUBES: COMPUTATIONS

Carbon nanotubes, originally discovered as byproducts of fuller- ene synthesis, are now considered to be the building blocks

of future nanoscale electronic and mechanical devices. It is therefore desirable to have a good understanding of their electronic and mechanical properties and the interrelations between them. In

particular, single wall carbon nanotubes (SWNT) provide a system

where the electronic properties can be controlled by the structure

of the nanotubes and by various deformations of their geometries

[1,2]. The physical properties can also be altered by intertube interactions between nanotubes packed in hexagonal lattices, as so-called

"nanoropes."

The intertube interactions in nanoropes can be probed by

applying external pressure to vary the intertube distance. For fullerenes, such high pressure studies have yielded many interesting

results including new compounds such as the pressure-induced polymeric phases of C^,. It is, therefore, of interest to inquire if similar

covalent-bonding can occur between the nanotubes in a rope. This

could have important consequences for nanoscale device applications and composite materials that require strong mechanical properties since nanoropes consisting of inter-linked SWNT will be significantly stronger than nanoropes composed of van der Waals (vdW)

packed nanotubes. We investigated possible new pressure-induced ground state

structures for (n,0) nanotube ropes from first-principles total energy

calculations using the pseudopotential method within the generalized gradient approximation (GGA) [1]. For simplicity, we model

the nanoropes as a hexagonal lattice of nanotubes with one nanotube per unit cell. The pressure dependence of the lattices of nanotubes was determined by calculating the total energy as a function

of nanotube separation (i.e., a and b) while the other parameters,

including atom positions, c, and 7 are optimized. We observe that

(7,0) nanotubes become elliptically distorted with applied pressure

(i.e., decreasing nanotube-nanotube distance). At a critical pressure, we observe a structural phase transformation from the vdW nanotube lattice (as shown in Fig. la) to a new lattice in which the nanotubes are interlinked along the [110] direction, where the strain

of the nanotube is largest (Fig. lb). The covalent bonding between

nanotubes is therefore the result of curvature-induced re-hybridization of the carbon orbitals. The same structural transformation was

observed for the other (n,0) nanoropes. To quantitatively study the bonding mechanism, we calculated

the total energies of the different phases as a function of the lattice

constant (i.e., applied pressure). The result for (7,0) nanotubes is summarized in Fig. 2. The energies of the vdW and the one-dimensional interlinked phases cross each other at about a = 9.0 A with

an energy barrier of only 46 meV/unitcell (552 K). The pressure

required to attain this lattice constant is only about 0.3 GPa for

the vdW phase, indicating that polymerization of vdW (7,0) nanoFIGURE 1. Optimized structures of the vdW (7,0) (a), and one- dimensional interlinked (7,0) (b) nanotube lattices. The interlinked structure shown in (b) has lower energy than vdW packed (7,0) nanotubes shown in (a).

18 RESEARCH HIGHLIGHTS
T. Yildirim NIST Center for Neutron Researcti National Institute of Standards and Technology

Gaitfiersburg, MD 20899-8562

0. Gulseren

NIST Center for Neutron Researcfi National Institute of Standards and Technology

Gaithersburg, MD 20899-8562

and

Department of Materials Science and Engineering

University of Pennsylvania

Philadelphia, PA 19104

Lattice constant (A)

FIGURE 2. Planer lattice constant variation of the total energy of (7,0) nanotube

ropes in three different phases. Inset shows the view of the structures along

c-axis. The zero of energy was taken to be the energy of vdW packing of the nanotubes.

ropes could occur at modest pressures and temperatures. Once the

interlinked phase is reached, the energy barrier required to break the bonds and obtain free nanotubes is about 0.7 eV (25 meV/atom),

which is comparable to that of ID polymerized Qg molecules

(20 meV/atom).

Figure 2 also shows that another interlinked phase of (7,0) nanotubes becomes the ground state for lattice parameter smaller

o than 8.0 A. In this new phase the nanotubes are interlinked along

both a- and b-axes (see Fig. 3a). This 2-D interUnked structure is

about four times stiffer than the 1-D interlinked phase and sixteen

times stiffer than the vdW nanoropes. We observe that applying even higher pressures yields more

complicated and denser phases for many of the nanoropes studied

here (see Fig. 3). For (9,0) nanoropes, we find that the nanotubes

are interlinked along three directions forming a hexagonal network. The length of the intertube bond, d^.(- = 1.644 A, is significandy

elongated for a sp^ C-C bond. The two dimensional interlinked phase of (7,0) nanotubes is further transformed to a denser structure

at 30 Gpa with a band gap of 2 eV (Fig. 3c). By comparison, (6,6) nanotubes do not form an interlinked structure up to a pressure

of 60 GPa. Rather the nanotubes are hexagonally distorted such

that the local structure of the nanotube faces is similar to that in

FIGURE 3. Various high density phases of carbon nanotubes. (a) Twodimensional interlinked structure of (5,0) nanotubes, consisting of rectangularly distorted nanotubes interlinked on a 2-D network, (b) A hexagonal network

of (9,0) nanotubes, (c) A very dense structure of (7,0) nanotubes obtained under 30 GPa pressure, (d) The optimized structure of (6,6) nanotubes under P= 53

GPa.

graphite sheets (Fig. 3d). Furthermore, releasing the pressure yields

the original structure, indicating that the distortion is purely elastic. The structural changes clearly have strong effects on the electronic

properties [2] and therefore should be detected in the pressure dependence of various transport properties of nanoropes. The new pressure-induced, high density phases [1] reported

here may provide a way of synthesizing novel carbon base materials

with interesting physical properties. For example interlinking of the nanotubes may improve the mechanical performance of composites

based on these materials. The change in the band gap of a SWNT

with applied pressure can be exploited to realize various quantum

devices on a single nanotube with variable and reversible electronic

properties [2]. It will be an experimental challenge to confirm the

structures predicted here. A difference-INS spectrum of two identical samples, one treated with pressure and the other not, may give some evidence for the new phases.

REFERENCES

[1] T. Yildirim, 0. Gulseren, C. Kilic, and S. Ciraci, Phys. Rev. B 62, 12648 (2000).

[2] C. Kilic, S. Ciraci, 0. Gulseren, and T. Yildirim, Phys. Rev. B 62, R 16345 (2000).

NiST CENTER FOR NEUTRON RESEARCH 19
DYNAMICS CHANGES IN THE

MOLTEN GLOBULE-NATIVE FOLDING STEP

The function of a protein depends critically on its ability to

adopt a specific structure. Remarkably, a protein can fold efficiently to this native state from the many unfolded states on physiological time scales. Understanding how this process occurs is one

of the great challenges in biology. Proteins can also form partially

folded, collapsed states under both equilibrium and non-equilibrium

conditions [1,2]. Such partially folded proteins resemble the intermediate states along the protein folding pathway, and thus play an

important role in understanding the mechanisms of protein folding. Moreover these partially folded proteins have also been shown to

participate in important cell functions. A molten globule is a compact, partially folded protein that

has native-like secondary structure and backbone folding topology,

but lacks the extensive, specific side-chain packing interactions of

the native structure [3]. Structural studies have shown that the sidechains in a molten globule can adopt a greater variety of conformations than in a native protein. The ability of the side chains to form

the tight and specific interactions typical of a native protein, is the

essential final step in the protein folding pathway. This packing

process is considered to be energetically more difficult than forming

the collapsed, disordered folding intermediates. However, little is known about the dynamics of this mostly folded state.

In order to understand the changes in protein dynamics that

occur in the final stages of folding, we have used incoherent

quasielastic neutron scattering (IQNS) to probe the differences in

the dynamics between the native state and the almost completely

folded, molten globule state of the protein, bovine a-lactalbumin

in solution [4]. Because hydrogen scatters neutrons much more

strongly than deuterium, the exchangeable protons were deuterated and DjO was used as the solvent. The scattering from the protein is

then dominated by the non-exchangeable protons in the side-chains.

Figure 1 shows the measured scattering function, S( Q, (o), of bovine

a-lactalbumin (BLA) and its molten globules (MBLA), as a function

of the energy transfer ho)d\. a momentum transfer 2 = 1-08 A '. The broader quasielastic peak of MBLA indicates that the side-chain

protons within the molten globules move significantly faster than

those in the native protein, which reflects the lack of the specific

side chain interactions in MBLA compared to BLA.

In addition to the time scale, IQNS yields information on

the geometry of the observed motion through the ^-dependence of

S{Q, 0)). We have analyzed the g-dependence for BLA and MBLA

_ 0.05

CO i 0.00^

CD"-0.05

0.8

0.6

:- 0.4-

C/3

0.2

0.0-^

-0.4 -0.2 0.0 0.2 Energy (meV)

0.4

MBLA at Q-1.08 A0.0&

-0.2 0.0 0.2 Energy (meV)

FIGURE 1. The quasielastic neutron scattering spectra, S(Q, w) of BLA and

IVIBLA (In arbitrary units), measured as a function of the energy transfer fia> at Q = 1.08 k \ The solid lines are fits to the data while the dashed lines show the two components described in the text.

20 RESEARCH HIGHLIGHTS
Zimei Bu and Charles C. Han

NIST Polymers Division

National Institute of Standards and Technology

Gaittiersburg, MD 20899-8542

Dan A. Neumann, Seung-Hun Lee, and Craig M. Brown

NIST Center for Neutron Researcfi National Institute of Standards and Tectinology

Gaittiersburg, MD 20899-8562

Donald M. Engelman

Department of Molecular Bioptiysics and Biochemistry

Yale University New Haven, CT 06520-8114

using a model where some of the protons diffuse within a spherical

cavity, while others are fixed on the = 70 ps time scale of these measurements. This is intended to capture the physical picture of

side chain motion within a constrained volume imposed by the backbone topology of the protein. Within this model, the scattering

consists of two components, a 5-function and a Lorenztian, each broadened with the experimental resolution = 60 |ieV. Typical fits

for individual spectra are shown in Fig. 1.

Figure 2 shows the half-width at half-maximum Fof the

Lorenztian component of the scattering as a function of Q-. The

initial linear region indicates that on longer length scales (small Q),

the protons undergo spatially-restricted diffusive motions, while the

crossover to a consant width at higher Q reflects the granularity

of the motion at these shorter, atomic length scales. The elastic

incoherent structure factor, which gives the time-averaged spatial

distribution of the protons, is formed by dividing the intenstity of

the elastic (8-function) component by the total integrated intensity

measured at each Q. The EISF is shown as a function of Q in Fig.

3. The soUd lines show fits to the EISF expected for diffusion within

a sphere, showing that the length scale of the motion increases by

about 25 % as the side chains become disordered. This is in contrast

with the usual situation where slower motions tend to cover larger

length scales. The fact that the EISF plateaus at a higher value for BLA than MBLA indicates that more of the side chain protons are immobilized in the protein's native state. The mean square amplitude <j/^> of the high-frequency vibrational modes can be obtainted from the ^-dependence of the total

scattering intensity through the Debye-Waller factor. The values

of <U'> extracted in this way are indistinguishable for BLA and

MBLA, which suggests that chemical bond vibrational motions do

not change significantly in the final stage of protein folding.

Overall, these results demonstrate that the side chains in molten globules are significantly more mobile than those in the native

protein, and explore a larger length scale in a shorter time. This

indicates that the specific side chain interactions responsible for the

final step in protein folding both localize and slow the motions of

the side chains. REFERENCES

[1] K. A. Dill, Biochemistry 29, 7133 (1990).

[2] D. Shortle, FASEB J. 10, 27 (1996).

[3] O. B. Ptitsyn, Adv. Protein. Chem. 47, 83 (1995).

[4] Z. M. Bu, D. A. Neumann, S.-H. Lee, C. M. Brown, D. M. Engelman, and C. C. Han,

J. Mol. Biol. 301, 525 (2000).

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

CO

1.0

0.8

0.6-

0.4-

0.2

fit BLA with one sphere: Rbla= 4.1 ±0.1 A

fit MBLA with one sphere: Rmbla= 5-4±0.1A

hi:

0.0 0.4 0.8 1.2 1.6 2.0 Q {K')

FIGURE 2. The half-width at half-maximum F of the quasielastic Lorentzian peak as a function of the momentum transfer Q^, () is for BLA and (O) is for MBLA. The r vs. Q plot reflects the length dependence of the decay rate of the self-correlation function and is a measure of the mobility of the protons

within the protein.

FIGURE 3. The elastic incoherent structure factor (EISF) of () BLA and

(o) MBLA. The lines are fits to the EISF expected for diffusion within a

sphere. The fits show that the length scale of the motion in MBLA is about 25 % larger than in BLA.

NiST CENTER FOR NEUTRON RESEARCH 21
SOFT PHONON ANOMALIES IN RELAXOR

FERROELECTRICS

Our current phonon studies of ferroelectrics at the NCNR are

part of a systematic investigation of ABO3 perovskite oxides

that exhibit exceptionally high piezoelectric responses. Two solid

solutions, (Pb[Zn,/3Nb2/3]03),.XPbTi03), (PZN-jPT) and (PbZrOj),.^

(PbTiOj)^ (PZT) have been extensively investigated in recent years. A common feature of these two systems is the morphotropic phase

boundary (MPB), which separates the tetragonal and rhombohedral

regions of the T-x phase diagram. The maximum piezoelectric activity is located on the rhombohedral side of the MPB for both systems. PZN-jcPT, however, can sustain ultrahigh strain levels, with < 1 % hysteretic loss, fully one order of magnitude larger than

those attainable with conventional PZT-based piezoelectric ceramics. These two remarkable properties suggest that PZN-xPT holds great promise for the next generation of solid-state transducers. '

The compositions of the perovskite B-sites of PZN-xPT and

PZT differ in a key respect. Whereas an isovalent mixture of Zr*+ and Ti''+ ions occupies the PZT B-site, a more disparate group of

heterovalent Zn-+, Ti^*, and Nb'* ions shares the PZN-xPT B-site.

This creates intense quenched random electric fields that are thought

to produce the so-called relaxor phase, which is characterized by a

diffuse phase transition and a broad and strongly dispersive peak in

the dielectric susceptibility. Despite years of research, the physics of

this diffuse phase transition is still not well understood. In prototypical ferroelectric systems such as PbTi03, it is well known that

the softening of a zone-center transverse optic (TO) phonon drives

the transition from a cubic paraelectric phase to a tetragonal ferroelectric phase. In relaxor compounds such as pure PZN, however,

the mixed-valence character of the B-site sharply breaks the translational symmetry, resulting in much more complex lattice dynamics.

In fact, no definitive evidence for a soft mode has been found in

these relaxor systems.

Motivated by these results, we have examined the lattice dynamics of the polar TO phonon mode in a high quality single

crystal of PZN-8 %PT, for which the measured value of the piezoelectric coefficient J33 is a maximum. Figure 1 shows neutron scattering data taken on PZN-8 %PT in its cubic phase at 500 K

50 K above r.) [1]. The maximum scattered neutron intensity

has been plotted as a function of energy transfer h(0 and momentum

transfer q along the syrrmietry directions [110] and [001]. The

lowest-energy data points trace out a normal TA phonon branch

along both [110] and [001]. What is striking, however, is that Fig.

1 shows no evidence of a zone center TO mode at all. Instead,

the data suggest a precipitous drop of the TO branch into the TA

branch, somewhat resembling a waterfall. This anomalous feature is

highlighted by the shaded regions in Fig. 1, and stands in marked

contrast to the behavior of PbTi03 where the same TO phonon

branch intercepts the ^coaxis at a finite energy. To clarify the nature of this unusual observation, we show a

constant-^ scan at h(0 = 6 meV in Fig. 2 along with a constant-|2

scan in the insert [1]. Both scans were taken at 500 K near the (220)

Bragg peak, and along the [001] direction. The small horizontal

PZN-8 %PT

-0.3 -0.2 -0.1

(h,h,4) (rlu)

0.2 0.4

(2,2,0 (rlu)

FIGURE 1 . Solid dots represent positions of peak scattered neutron intensity taken from constant-Q and constant-f scans at 500 K. Vertical (horizontal) bars represent phonon FWHM linewldths. Solid lines indicate TA and TO phonon

dispersions.

22 RESEARCH HIGHLIGHTS
p. M. Gehring S.-E. Park G. Shirane

NIST Center tor Neutron Research, Materials Research Laboratory Physics Department

National Institute of Standards and Technology The Pennsylvania State University Brookhaven National Laboratory

Gaithersburg, MD 20899-8562 University Park, PA 16802 Upton, NY 11973

bar shown under the left peak of the constant-f scan represents

the instrumental FWHM ^-resolution. We see immediately that the

constant-Q scan shows no evidence of any well-defined phonon

peak, most likely because the phonons near the zone center are overdamped. However, the constant-f scan indicates the presence of

a ridge of scattering intensity at ^=0.13 r.l.u., or about 0.2 A '.

Thus, the sharp drop in TO branch that appears to take place in

Fig. 1 does not correspond to a real dispersion. Rather, it simply

indicates a region of (^a},^)-space in which the phonon scattering

cross section is enhanced. The question remains why does this happen?

In 1983 Bums and Dacol proposed a seminal model for the

disorder intrinsic to relaxor ferroelectrics [3]. Using measurements

PZI\I-8%PT

450

400

350

E 300

o 250

200

150

100

400 r

300 - E

200 - CO

Cour 100 -

-I—I—I—I—1—I-

••tt

0 5 10 15 20 E (meV)

of the optic index of refraction on a variety of samples, including

single crystals of PZN, they demonstrated that a randomly oriented

local polarization develops at a well-defined temperature several hundred degrees above the transition temperature T^. The origin

of this local polarization, not present in normal ferroelectrics above

T^, was conjectured to arise from the formation of polarized microregions (PMR) of the crystal that are richer in Nb5+ than the average chemical formula. The presence of such randomly oriented PMR above in PZN-8 %PT should effectively impede the propagation of polar

phonon modes whose wavelength exceeds the size of the PMR.

The observation that the phonon scattering cross section is dramatically affected = 0.2 A ' from the zone center gives a measure of

the dynamic size of these polarized domains. If the length scale

associated with the anomalous "waterfall" is of order 271/^, this would correspond to 3 1 A, or about 7 to 8 unit cells, a size that

is consistent with Bums and Dacol's conjecture. We have recently

been able to model this behavior quite well for PZN using a simple

coupled-mode that assumes a highly ^-dependent linewidth r(q)

that increases sharply for q < 0.2 A ' [2]. Hence we speculate that

the striking anomalies in the TO phonon branch shown in Fig. 1 (the same branch that goes soft at the zone center at 7"^, in PbTiO,) for q <

0.2 A-' are directly caused by these PMR which serve to dampen the zone center TO phonon modes. If true, then this unusual behavior

should be observed in other related relaxor systems. Direct evidence

for this has already been observed at room temperature in neutron

scattering measurements on PMN (M = Mg) [4]. REFERENCES

[1] p. M. Gehring, S.-E. Park, and G. Shirane, Phys. Rev. Lett. 84, 5216 (2000).

[2] P M. Gehring, S.-E. Park, and G. Shirane, to be submitted to Phys. Rev. B.

[3] G. Bums and F. H. Dacol, Phys. Rev. B 28, 2527 (1983); ibid. Solid State Commun.

48, 853, (1983).

[4] P. M. Gehring, S. B. Vakhrushev, and G. Shirane, in Proceedings of the Fundamental

Physics of Ferroelectrics 2000 Winter Workshop, Aspen, 2000, edited by R. E. Cohen

(American Institute of Physics, 2000), p. 3 14.

.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.

(2,2,^) (r.l.u.)

FIGURE 2. Constant-Escan measured along [001] at 6 meV at 500 K near the

(220) Bragg peak. Solid line is a fit to a double Gaussian function of C,. No peak

is discernible in the constant- Q scan shown in the insert.

NiST CENTER FOR NEUTRON RESEARCH 23
LITHOSILICATES: A NEW FAMILY OF

MICROPOROUS MATERIALS

j jMMMhenever you have a novel structure you usually get novel WW properties." Edith M. Flanigen [1] (First winner of the

International Zeolite Association lifetime contribution and achieve- ment award).

Zeolites and related microporous materials contain regularly

spaced molecule-sized pores and are fascinating examples of molecular engineering. More than just aesthetically inspiring, as can be

seen in Fig. 1, these materials represent billions of dollars in commerce, as they have widespread industrial applications: Materials of

this type are used as catalysts to produce gasoline and pharmaceuticals. For medical and industrial purposes, they are employed to separate N,, 0,, and other gases. Formulated in household detergents,

they remove the calcium ions that make water "hard," replacing

environmentally unfriendly phosphates. Zeolites and related microporous materials are also employed to sequester radioactive ions

for bioremediation. Many new applications are being investigated

in areas such as selective membranes, batteries, and fuel cells.

Properly used, the term

zeolite should be restricted to

naturally occurring aluminosilicates. However, related micro- porous materials (herein called

zeolitic) have been synthesized,

where elements such as B, Be,

Cr, Fe, Ga, Ge, Mn, P, Ti, and

Zn substitute for tetrahedrally

bonded Si or Al. These atoms

have roughly the same bonding

configurations, so they tend to

adopt the same framework connectivities as aluminosilicates and thus have the same pore

structures. Further, since each

tetrahedral (T) atom is linked by

four oxygen atoms, the framework must have a generalized chemical lorniula [7D2],.^'"[r'02]/

where the charge on each tetrahedral unit {m or n) is typically zero

or - 1 . Additional extra-framework cations, such as H+, Na+, Li+, or

Ca-+, are then needed to balance changes. The number and nature of

these cations is significant as cations are often the chemically active

site for interactions with guest species, or their presence may affect

the framework properties. Thus, they may dictate the catalytic or

sorptive properties of the material. Empirically, the most negatively

charged zeolitic frameworks that have been found, e.g., those that have the largest number of extra-framework cations, are materials

with formula M+[SiOJ[A10,] '. Pauling's rules, restated in the zeolite field as Lowenstein's rule, dicate that the ratio of Al:Si cannot exceed unity, limiting the cation fraction to 1/7 the total number

of atoms. A new class of materials that have Li incorporated as a

tetrahedral framework species has recently been discovered [2,3].

FIGURE 1. The RUB-29 framework. Tetrahedral SI and LI atoms are shown as solid yellow and blue spheres, respectively at

their approximate covalent radius (1 A). Framework 0 atoms are shown as transparent red spheres at their approximate Van der Waals radius (1 .4 A). Extra-framework species are omitted for clarity.

24 RESEARCH HIGHLIGHTS
So-Hyun Park

Department of Geosciences -

State University of New Yorl< at Stony Brook

Stony Brool< NY 11790-2100

and NIST Center for Neutron Researcti National Institute of Standards and Technology

Gaithersburg, MD 20899-8562

John B. Parise, Maiming Liu, and Clare P. Grey

Chemistry Department and Department of Geosciences

State University of New York at Stony Brook

Stony Brook, NY 11790-2100 Hermann Gies

Institut fur Geologie, Mineralogie, Geophysik

Ruhr-Universitat-Bochum Bochum, D-44801, Germany

Brian H. Toby

NIST Center for Neutron Research

National Institute of Standards and Technology

Gaithersburg, MD 20899-8562

These materials, called microporous lithosilicates, are novel for two reasons. One is that [LiO^] tetrahedra appear more flexible

than other [7DJ tetrahedra. This means that hthosilicates can bond in configurations that are too strained to exist for other silicates. Thus, lithosilicates offer the promise of new famihes of

pore structures. Second, the general formula for these materials is

M^/lSiOjli.JLiO^]^^', so that hthosilicates have the potential to be more negatively charged than aluminosiUcates, if the Li:Si ratio

exceeds 1:4. A team of NCNR scientists and collaborators has recently

completed the first complete structural characterization of a microporous lithosilicate, RUB-29. To determine the framework geometry,

synchrotron diffraction measurements were performed at the NSLS

using an extraordinarily small single crystal — with dimensions 10

|im X 10 |im X 2 (im. (For comparison, human hair is typically

50 \im to 100 ^im thick.) With 35 symmetry-unique atoms comprising the framework, RUB-29 is one of the most complex zeolitic

structures. Powder neutron diffraction at NIST was then used to

better determine the siting of the framework Li atoms, as well as

four additional extra-framework Li atoms and seven other extra- framework species. The RUB-29 framework is shown in Fig. 1. The structural studies of RUB-29 demonstrate two novel

structural building blocks, a Li,Si-spiro-3,5 and a Li,Si-spiro-5 unit

(see Fig. 2). It should be noted that both these building units contain

"three-rings" where three T atoms, in this case one Li and two Si

atoms, are bonded in a cyclic structure. This three-ring structural

entity is highly strained in silicates; only one silicate example has

ever been found.

In RUB-29. only 1 in 5 T atoms are Li, so the total framework

charge is comparable to 1:1 aluminosilicates. However, RUB-29

appears to be stable under conditions where these high-aluminum

zeoUtes tend to degrade. Further, there is promise that new lithosilicate materials can be synthesized with even higher Li:Si ratios. Another interesting property exhibited by RUB-29 is that the

Li atoms, both in framework and non-framework sites, appear to move on an NMR timescale at temperatures as low as 250 °C. Much

more work is needed to learn about conduction in this material, but

it may hold promise for ionic conduction applications, such as in

batteries. REFERENCES

[1] S. Borman, R. Dagani, R. L. Rawls, and R S. Zurer, Chemical & Engineering News,

January 12, 1998.

[2] S.-H. Park, R Daniels, and H. Gies, Microporous Mater. 37, 129 (2000).

[3] S.-H. Park, et al. Journal of the American Chemical Society (2000), in press.

FIGURE 2. Li,Si-spiro-3,5 (left) and Li,Si-splro-5 (right). Small red circles indicate the centers of [SlOJ-tetrahedra, and big blue circles are those of [LiOJ-tetrahedra. The 0 atoms that bridge each pair of Si and Li atoms have been omitted to improve clarity.

NIST CENTER FOR NEUTRON RESE 25
QUANTIFICATION OF PHASE FRACTION AND

AMORPHOUS CONTENT

While many methods can be used to determine the elemental composition of a material, diffraction is one of the few

techniques that is also sensitive to the physical arrangement of atoms and molecules in the solid state. Even phases with the same

chemical composition, such as graphite and diamond, have different

diffraction patterns, dictated by the particular structure of each substance. The diffraction pattern from a mixture is the weighted sum

of the patterns from each phase that is present, making it possible

for quantitative phase composition to be determined. Prior to the

application of Rietveld refinement techniques to the problem of

quantitative phase analysis, these measurements required difficult

calibrations and were often imprecise. However, Rietveld analysis

involves the fitting of the entire diffraction pattern of each component phase based upon a structural model of the material and no

standards or prior calibration is required. It should be noted though

that even Rietveld analysis could not be used direcdy to quantify

materials with unknown structures or amorphous phases, since such

materials cannot be modeled crystallographically. An example where

quantitative phase analysis explains the inevitable failure of ceramic

thermal barrier coatings was presented in the 1998 NCNR Annual

Report.

NIST participation in a round robin on determination of

quantitative phase abundance, sponsored by the International Union

of Crystallography Commission on Powder Diffraction, provided

an excellent opportunity to demonstrate the high quality of data

obtained using the 32-detector NCNR high-resolution powder diffractometer at BT-1. The NCNR implementation of the Rietveld

technique for phase quantification was found to give excellent agree- ment with the nominal compositions. In addition, a new method for determining the amorphous phase content of a mixed-phase sample

without sample adulteration was validated. Data were collected using a Cu(31 1) monochromator

{X = 1.5402 A) and 15' incident collimation, and were then processed in the usual procedure to obtain a pseudo-single detector data

set. The phase fractions were determined using standard Rietveld

refinement techniques, including full refinement of crystallographic

and instrumental parameters, as implemented by the GSAS suite

of programs. Results for a sample consisting of nearly equal mass

fractions of AljO,, CaF,, and ZnO, along with values reported by

the other round-robin participants, are given in Table 1 ; the results obtained at NIST for all other samples are reported in Table 2 along with the nominal phase content. It can be seen from Table

Table 1. Mass fractions (%) of three-phase mixture reported by round robin

participants. The ranges are reported for 111 x-ray determinations, 7 neutron

determinations, and 4 synchrotron determinations. Standard uncertainties are reported in parentheses for the XRF (x-ray fluorescence, 3 determinations as

reported by the organizers) and NIST results (determined from the least-squares

refinement).

Phase Weighed XRF x-ray Neutron Synchrotron NIST

AI2O3 31.4 31.7(1) 22-49 29-32 31-35 31.7(1)

CaFj 34.4 33.9(1) 19-42 32-39 34-35 33.9(1)

ZnO 34.2 34.0(1) 25-42 32-35 29-35 34.4(1)

1 that neutron data give significantly more accurate results than

synchrotron or laboratory x-ray data, and that the results obtained at NIST are exceedingly good. The high accuracy of these results can be attributed to the intrinsic Gaussian fine shape of the reactor

neutron source, as well at to the lack of microabsorption and preferred orientation effects that frequently plague x-ray data but are normally negligible with neutron data. The data presented in Table

2 further confirm this conclusion, in that the results for sample 2

(preferred orientation), sample 3 (amorphous content) and sample 4

(microabsorption) all agree well with the nominal phase content. The determination of amorphous content in a crystalline sample has traditionally involved integration of the area under the broad

amorphous hump, giving the relative intensity compared with that of

the Bragg scattering. However, in multiphase samples this technique

is impractical. An alternative approach is to add a known quantity of

a material as an internal intensity standard. The unique properties of neutron diffraction suggested an

alternative approach. Since absorption is negligible for most elements, and since the entire sample is irradiated in the neutron beam,

a strategy based on absolute scattering intensities using an external

standard was devised.

In the Rietveld technique, the mass of each crystalline phase,

Wj, is proportional to the product of the scale factor for that phase,

5-, and the molecular weight of the unit cell contents (Z-M) where Zis the number of formula units per unit cell and M. is the molecular

weight. Thus for a crystalline multiphase sample of mass w^, {w^ = X W-) the relation °c X^iZ-Mj is true. The proportionality constant

can be determined using mass w^^^ of a completely crystalline known

standard under identical data collection conditions, so the relation

^c^^std = (^^'^i^i^iVC'^std^^std^std) be used. If the sample mass, w^,

26 RESEARCH HIGHLIGHTS
J. K. Stalickand B. H. Toby

NIST Center for Neutron Research

National Institute of Standards and Technology

Gaithersburg, MD 20899-8562

Table 2. Comparison of nominal phase composition (%) with that obtained

at NIST. The weighed and XRF values were provided by the round

robin organizers. Standard uncertainties for the NIST results are given in parentheses.

Sample Component Mass fraction Mass fraction Mass fraction weighed XRF NIST

1a AI2O3 1.2 1.2 1.3(1)

L.ar2 0^ Q 94.0 94.1 94.0(0) ZnO 4.0 4.1 3.9(1)

1b AI203 94.3 94.7 94.4(3)

A 0

4.0 4.0 4.2(1) ZnO 1.4 1.4 1.4(1)

1c AI2O3 5.0 5.1 4.9(1) CaFj 1.4 1.3 1.4(1) 7nn 30.0

Id AI2O3 13.5 13.8 13.7(1) CaF, 53.6 53.0 53.0(2) ZnO 32.9 33.0 33.3(1)

1e AI2O3 55.1 55.8 55.4(2) CaFj 29.6 29.4 29.2(1) ZnO 15.3 15.3 15.4(1)

If AI2O3 27.1 27.3 26.7(1) CaF2 17.7 17.4 17.5(1) ZnO 55.2 54.9 55.8(2)

2 AI2O3 21.3 20.9 21.9(4) CaFj 22.5 24.1 22.0(4) ZnO 19.9 19.5 19.1(6) Mg(0H)2 36.3 36.1 37.0(3)

3 Amorphous 29.5 27.1 32.3(6)

AI2O3 30.8 31.1 30.7(6) CaF^ 20.1 19.9 18.7(3) ZnO 19.7 19.6 18.3(3)

4 AI2O, 50.5 50.4 50.5(3)

FSjO', 19.6 19.6 20.3(2) ZrSiO, 29.9 29.5 29.3(4)

also contains an amorphous component, w\, then since = -

and the amorphous fraction/^ = m>\ I w^, then

/a=1

•

Using the GSAS suite of programs, the values for 5) may

be obtained from the product of the overall scale factor and the

"phase fraction," or by fixing the overall scale factor to 1.0 so that

the refined "phase fractions" are in fact the Rietveld scale factors

for each phase.

In order to make sure that data on the unknown and standard

materials were collected under identical conditions the automated

sample changer was used, the sample volume was reduced to ensure

complete sample irradiation, and identical data collection parameters were employed. In this way, data on any number of unknowns

could be compared to a single standard sample since no changes were made to the experimental conditions. An additional benefit was

that no adulteration or mixing of the samples was necessary. This

technique was used with several single-phase samples in order to compare the crystallinity of potential standards as well as of the unknown samples. In fact, the round robin organizers subsequently

sent samples of each of the unmixed phases to NIST for analysis.

The results obtained for the round robin sample with amorphous

content gave excellent agreement with the mass fractions determined

by weighing (see Table 2); the slightly higher amorphous content

obtained using the neutron Rietveld technique is explained by the

presence of a small amount (1 % to 2 %) of amorphous material in

the component crystalline phases.

This external standard technique to determine amorphous content could also be used to determine the mass fraction of a crystalline phase with an unknown structure. For both applications, however, obtaining the best results depends upon obtaining the best diffraction data. The unique capabilities of the NCNR high-resolution

diffractometer at BT-1 make this possible; these are summarized

below. FEATURES OF THE BT<1 DIFFRACTOMETER

Automatic six-carousel locking sample changer (vanadium sample

cans), ideal sample size: 10 cm\

Maximum beam size: 15 mm width by 50 mm height.

Coliimations: 15' or 7' before monochromator, 20' before

sample [30' for Si(531)], 7' before detectors.

Detectors: 32 ^He-filled detectors at 5° intervals; 13° scan

range covering 2^ from 0° to 167°. Monochromators:

Monochromator In-pile Monochromator Relative Flux Wavelength Typical

crystal and Collimation Bragg (neutrons s' (A) run times

Bragg plane angle (') Intensities cm-') (h)

Ge(311) 15 75 3.34 700 000 2.0784 0.5-5

Ge(311) 7 75 1.84 400 000 2.0795

Cu(311) 15 90 1.00 400 000 1.5401 3-12

Cu(311) 7 90 0.59 200 000 1.5405

Si(531) 15 120 0.47 200 000 1.5903 6-24

Si(531) 7 120 0.33 100 000 1.5904

NIST CENTER FOR NEUTRON RESEARCH 27
DIFFRACTION ELASTIC CONSTANTS FOR ARBITRARY

SPECIMEN AND CRYSTAL SYMMETRIES

Accurate determination of residual stresses by means of diffraction relies on the knowledge of the elastic constants that

translate lattice strain into macro-stress. Because of the difference between the elastic behavior of the aggregate and that of a single

crystallite, the straightforward relationship between strain and stress

as mediated by single crystal or polycrystal elastic constants no

longer holds. Instead, the relationship between lattice strain and

macro-stress is mediated by diffraction elastic constants (DEC).

Very recently, we proposed a theory that allows a transparent

calculation of DEC. This theory applies for almost the entire range

of polycrystalline elasticity, including that for aggregates of arbitrary

phase composition and arbitrary symmetry, both of the aggregate

and of the constituents [1]. Results show that for a particular crystallographic plane (hkl) and an arbitrary anisotropic material there are

usually six independent DEC. These DEC depend on the orientation

of the scattering vector, on the grain shape, and on the elastic

constants both of the crystallites and of the aggregate. Figure 1 shows Young's modulus vs. the orientation parameter for different

crystallographic planes (hkl) of two plasma-sprayed coatings with

different types of anisotropy. Calculated DEC for comparison to measurement were not previously available.

Figure 1 also illustrates the difference between the anisotropy

of the aggregate and that of the crystallites that comprise the

aggregate. The slope of vs. F depends mostly on the ratio

FIGURE 1. Young's modulus vs. orientation parameter for a metallic nickel coating and a ceramic YSZ (Zr02-t-8%Y203) coating deposited by plasma spraying. 200 -

Solid lines indicate calculated values, points are measured values.

FIGURE 2 . Central section of the representation surface for Young's modulus

in a nickel coating and a yttria stabilized zirconia coating. The length of the radius vector for a certain tilt angle is equal to Young's modulus

in units of GPa. These values were calculated from hkl-dependent elastic constants measured by neutron diffraction. The z-direction is perpendicular to the surface of the coating. All in-plane directions are equivalent due to the

transversal-isotropic elastic symmetry of sprayed coatings.

28 RESEARCH HIGHLIGHTS
Thomas Gnaupel-Herold

NIST Center for Neutron Research

National Institute of Standards and Tecfinology

Gaittiersburg, MD 20899-8562

and

University of Maryland

College Park, MD 20742

H. J. Prask

NIST Center for Neutron Researcti National Institute of Standards and Tectinology

Gaittiersburg, MD 20899-8562

2Cj4/(C|,-Cp) which is > 1 for nickel and < 1 for YSZ. The

aggregates exhibit generally transversal isotropic elastic symmetry

but again with a different anisotropy in the metallic coating

(C|[/C33< 1) and in the ceramic coating {CJC^^> 1). This anisot- ropy causes a substantial difference between normal and

perpendicular to the coating surface. While the data in Fig. 1 still depend on the crystallographic

plane {hkl) they can also be used to estimate the overall elastic

constants of the aggregates that, in turn, yield the directional dependence of the mechanical value of Young's modulus. This distribution forms a surface with rotational symmetry around the coating surface normal vector as illustrated by a central section shown in Fig. 2.

9 % interlamellar voids + 25 % vertical cracl<s, c/a=5 200

190

180

170 160

150

140

130

120

110

100

1 —YSZ: E normal to surface

—YSZ: E parallel to surface ^

1 \

- o o

-o 6 o« _ 0

1 1 1 1

The elastic anisotropy of sprayed coatings has its roots in

their microstructure. In the complete absence of preferred crystallite

orientation, the responsible factor is the porosity and alignment of elongated voids and cracks resulting from the spray process. These

voids can be treated as another phase with very low elastic moduli.

This way it is possible estimate the overall elastic constants if the

distribution of pore shapes and volume fractions are known.

In the case that the aggregate constants are akeady known,

the reverse approach of estimating a pore distribution can offer some

insight into the properties of different coatings. Figs. 3a and b show

where the best agreement was found for plasma sprayed metallic and ceramic coatings. The main difference is that the pore structure of the ceramic coating is dominated by interlamellar (horizontal)

voids, while the concentrations of horizontal voids and vertical

cracks are more balanced in the metallic coating.

REFERENCES

[1]. T. Gnaupel-Herold, J. Matejicek, and H.J. Prask, "Mechanical Properties of Plasma

Sprayed Coatings - Measured by Diffraction," to be published in Proc. of the 9th

Int. MetaUiirgical Conf. Metal 2000. Ostrava. Czech Republic, May 16-18, 2000;

T. Gnaupel-Herold, and H.J. Prask, "Diffraction Elastic Constants for Arbitrary Specimen and Crystal Symmetries: Theory and Practical Consequences," in Proc. of

the 6th Int. Conf. on Residual Stresses (ICRS-6), (lOM Communications Ltd., UK,

2000), pp. 243-250.

1 3 5 7 9 aspect ratio c/a of vertical cracks

11

6 % interlamellar voids (a/c=3)+ 4 % vertical cracks — Ni: E normal to surface — Ni: E parallel to surface

3 5 7 9 aspect ratio c/a of vertical cracks

FIGURE 3. Young's modulus for the YSZ coating (a) and for the nickel coating (b) vs. the pore aspect ratio. The vertical lines at aspect ratio of 10 indicate where

the best agreement is found with experimental results.

NIST CENTER FOR NEUTRON RESEARCH 29
DIRECT OBSERVATION OF SUPERHEATING AND

SUPERCOOLING OF VORTEX MATTER

Acurrent question of fundamental interest concerns whether a

vortex solid-Hquid transition exists in type-II superconductors

[1]. In addition to providing a possible model system for melting

and freezing, vortex matter offers unprecedented opportunities to

study the effects of quenched disorder on phase transitions. The

peak effect, where the critical current exhibits a peak rather than

decreasing monotonically with increasing temperature, has been

found to occur at the same temperature as a magnetization jump,

which suggests a melting of the vortex lattice. However, there has been no direct structural evidence indicating whether there is indeed

an underlying phase transition, and if so, whether it is solid-to-solid,

solid-to-liquid, or even liquid-to-liquid in origin. Moreover, since quenched disorder is known to have important consequences for phase transitions, whether a solid-liquid transition can occur when

random pinning is effective has broad implications in condensed

matter physics. Here we report the first observation of a striking history

dependence of the structure function of vortex matter in the peak

effect regime in a Nb single crystal, using SANS combined with

simultaneous magnetic susceptibility measurements [2]. Metastable

supercooled vortex liquid and superheated vortex solid phases have

been observed, providing direct structural evidence for a first-order

vortex solid-liquid transition associated with the peak effect. Measurements were performed on a Nb single crystal, with

the incident neutron beam nominally along the cylindrical axis which coincides with the three-fold symmetric <111> crystallographic direction. A superconducting magnet applies a dc magnetic

field along the same direction. The peak-effect regime is determined

in situ by measuring the characteristic dip in the temperature dependence of the real-part of the ac magnetic susceptibility as shown

in Fig. 1(a) for H = 3.75 kOe [2]. The pronounced diamagnetic dip

in %'(T) of the ac susceptibility corresponds to a strong peak effect

in the critical current. The onset, the peak, and the end of the peak

effect are denoted by T^{H), T^{H), and T^^{H), respectively. Figure

1(b) shows the window of the experiment. For each {T,H), we measure the SANS patterns for different

thermal paths. At sufficiently low temperatures the SANS images

show sharp Bragg peaks with six-fold symmetry, independently of

the thermal history. An example is shown in the inset of Fig. 1(b)

for H = 3.75 kOe and T = 3.50 K. However, the vortex pattern

starts to show striking history dependence as the peak-effect regime

is approached. We define the field-cooled (FC) state as when the

sample is cooled to the target temperature in a magnetic field, while

the zero-field-cooled (ZFC) state is reached by cooling the sample in

zero field to the target temperature and then increasing the magnetic

field to the desired value. For a field-cooled-warming (FC-W) state,

the system is cooled in-field to a low temperature ( = 2 K), then warmed back to the final temperature. For the FC path, the vortex patterns show nearly isotropic

rings for T^<T < T^, ^nd broad Bragg spots for T < T^. In contrast,

for the ZFC and the FC-W paths, sharp Bragg spots are observed

for all temperatures up to T^^ Shown in the top panel of Fig. 2 are

0.1

0

-0.1

^-0.2

-0.3 \-

-0.4

-0.5

0 2 4 6 8 1 0 T (K) H=3.75 kOe

T (K)

FIGURE 1. Peak effect and [H-Tj phase diagram of Nb. a) ac magnetic susceptibility for //dc = 3.75 kOe (field-cooled). H^^=3.3 Oe and 1 kHz. Inset: global N-r phase diagram for the Nb crystal used in this study, (b) Expanded view of the //-r phase diagram (shaded box in a). Two observed SANS Images of the

field-cooled vortex states are shown.

30 RESEARCH HIGHLIGHTS
X. S. Ling, S. R. Park, and

B. A. McClain

Department of Ptiysics Brown University Providence, Rl 02912

S.-M. Choi

NIST Center tor Neutron Research

National Institute ot Standards and Tectinology

Gaittiersburg, MD 20899-8562

and

University ot Maryland

College Park, MD 20742

D. C. DenderandJ. W. Lynn

NIST Center tor Neutron Research

National Institute of Standards and Technology

Gaithersburg, MD 20899-8562

the ZFC and FC images at (3.75 kOe, 4.40 K), which is just below

1^(3.75 IcOe) = 4.50 K. The images in the mid panel are for (4.00

kOe. 4.40 K), which is 0.10 K above rp(4.0 kOe) = 4.30 K. The

intensities at the radial maximum for the mid panel SANS data

are plotted in the lower panel. The sharp Bragg spots for the ZFC

state indicate a vortex lattice with long-range-order (LRO), while the

very broad spots for the FC state signify a disordered phase with

short-range-order.

The observed hysteresis suggests a first-order vortex solid- hquid (or glass) transition. A controversial issue is the location

60 120 180 240

e(deg.)

FIGURE 2. History-dependent SANS patterns at 4.40 K. The SANS images of the ZFC and FC vortex states for H= 3.75 kOe (top panel: below the onset of the peak effect) and //= 4.00 kOe (mid panel: near the upper end of the peak-effect

regime). The thick arrows indicate how the SANS images evolve after applying

a small ac magnetic field. The lower panel shows the intensity data at the

radial maximum as a function of the azimuthal angle for the ZFC and FC SANS

data(H=4k0e).

of the underlying equilibrium phase transition to the position of

the peak effect. One interpretation places the conjectured vortex

solid-liquid transition at T^, consistent with the recent experi- ments in YBCO. Another widely held view is based on the classical Lindemann criterion which would place T,,, at T^iW for Nb, provided the vortex-lattice elastic moduli remain well-behaved. In this

scenario, the FC disordered phase seen here (as well as in [3,4])

is a supercooled liquid and the thermodynamic ground state is an

ordered solid across the entire peak-effect regime. The third scenario

places at or below the onset of the peak effect. To experimentally determine the ground state and approxi- mate value of T^, the susceptibility coil was used to shake the vortex

assembly, using SANS to observe how the vortex structure evolves. The data show that above the Bragg peaks start to disappear

within the first 10- sec of the shaking experiment, demonstrating

that the equilibrium state is disordered. Similiarly, the FC disordered

states for T < Tp are metastable and the ordered ZFC state is the ground state, opposite to that for T > T^. In the T<T^ regime,

though, the metastabihty is obviously stronger since a much larger

ac field is needed to change the metastable state. We conclude that for T>T^ the ordered ZFC vortex lattice

is a superheated state and the ground state of the vortex system

is a disordered vortex Uquid, while for T<T^ the ground state is

a vortex Bragg solid and the disordered FC state is a supercooled

vortex liquid. A thermodynamic phase transition must therefore have

taken place, with ~ T^. These results also imply the absence

of superheating in conventional transport experiments with a large

drive current, which solves a longstanding puzzle in which the

history dependence of the nonlinear resistance always vanishes at

TJ^H)\ only with extremely low drive currents may one then observe

the subtle effects of superheating in transport. REFERENCES

[1] For a review, see G. Blatter, Rev. Mod. Pliys. 66, 1 125 (1994).

[2] X.S. Ling and J.I. Budniclt, in Magnetic Susceptibility of Superconductors and Other

Spin Systems, R.A. Hein, et al, eds. (Plenum Press, 1991), p.377.

[3] J.W. Lynn, et at.. Phys. Rev. Lett. 72, 3413 (1994).

[4] RL. Gammel, et al. Phys. Rev. Lett, 80, 833 (1998).

NIST CENTER FOR NEUTRON RESEARCH 31
SANS MEASUREMENTS OF NANOSCALE

LITHOGRAPHIC FEATURES

The continued growth of the semiconductor industry depends on advances in Uthographic processes and materials to enable

the economical production of smaller device features. Precise measurement of the size and quality of lithographically prepared features is critical as their sizes continue to decrease, with dimensions

approaching 100 nm. Cuixent microscopy-based techniques such as

scanning electron microscopy (SEM) and atomic force microscopy

(AI^) often require special modifications to enable the measure- ment of either the critical dimensions or feature resolution parameters. More importantly, these techniques become extremely challenging as feature sizes continue to decrease.

In this highlight, we demonstrate the powerful use of smallangle neutron scattering (SANS) to quickly, non-destructively, and

quantitatively characterize both the size and profile of lithographically prepared structures as prepared on a silicon wafer substrate

[1]. Until recently, SANS instruments were unable to measure lithographic feature sizes (sizes greater than 300 nm) and neutron beam

fluxes were insufficient to measure scattering from thin film structures. Today, with new focusing optics, the high intensity NCNR

instruments allow routine SANS measurements of smaller lithographic features [2]. Other important advantages for the use of SANS to measure lithographic structures include a) the measure- ment of structures on silicon, because single crystal silicon wafers

are generally transparent to neutrons, b) a measurement metric statistically averaged over an area of several square centimeters, and c)

less stringent SANS instrument requirements as lithographic structures decrease in size. As an example, periodic, equally spaced, parallel line patterns

with a nominal size of 150 nm were prepared on a silicon single

crystal wafer using standard 248 nm optical lithography, and placed

directly in and normal to the neutron beam. Quantitative measure- ments of the size and average profile of these lines are extracted from the scattering data. SEM micrographs of these structures are shown in Fig. 1. The SANS measurements were performed on the NG-7 30

m SANS line under ambient atmospheric conditions at the NCNR.

Newly developed neutron focusing optics consisting of 28 biconcave

MgFj lenses were used to access small enough angles to resolve

feature sizes up to 300 nm, a previously inaccessible length scale

for SANS. In this configuration, the SANS data provide quantitative

information about the line repeat distance and the quality of the line

structure. The 2-D scattering data from the structures displayed in Fig. 1

are shown in Fig. 2. The line structures are aligned with the vertical

FIGURE 1 . Top-down and side view scanning electron micrographs of the

lithographically prepared lines used in the SANS measurement. The lines are nominally 150 nm wide and 0.62 pm in height.

32 RESEARCH HIGHLIGHTS
Wen-li Wu and Eric K. Lin Polymers Division

National Institute of Standards and Tectinology

Gaittiersburg, MD 20899-8541

Qingliuang Lin and IVIarie Angelopolous

IBM

T. J. Watson Researcii Center Yorktown Heigtits, NY 10598

axis of the detector. Six orders of diffraction peaks are immediately

observed in the horizontal axis of the detector because of the highly

periodic pattern of the fabricated hnes. By linearly fitting the peak

position plotted as a function of the diffraction order index, the

feature repeat distance for the structure in Fig. 1 is determined to

be (3031 ±9) A. A more detailed analysis provides a quantitative determination

of the average profile of the line structures, including a measure

of the line-edge roughness (LER). We model the periodic Une pattern as a convolution of a periodic delta function with the average

cross-section of a line. In Fig. 3, the scattering intensity of a given

diffraction peak is plotted as a function of the position of the peak.

The solid line is the best theoretical fit to the experimental data and

corresponds to a measure of the LER of (213 ± 13) A. Also in Fig.

3, the second and fourth order diffraction peaks are visible and less

intense than the first and third diffraction peaks. The measurable

intensity of the even order diffraction peaks indicates that the line

feature size is slightly less than one half the overall repeat distance. The model fit results in a line feature size of (1350 ± 60) A.

The average line structural size and cross-section were deter- mined in a configuration where the sample was placed perpendicular

to the incident neutron beam. More three-dimensional information

about the average line structure can be obtained by tilting the line

pattern with respect to the incident beam. Varying projections of

the line profile onto the detector plane provide an elegant method

to deduce more specific structural information. In additional, the formalism to extend the SANS theoretical framework to arbitrary

shapes is well established and will be applied in the future. With

these advances, SANS may be used to identify resolution limits

in new nanofabrication processes and materials and to serve as an

important metrology tool in understanding the physical processes

that control the resolution of these methods. REFERENCES

[1] W, L Wu, E. K. Lin, Q. Lin, and M. Angelopolous, J. Appl. Phys., 88. (2000)

(in press).

[2] S.-IVI. Choi, J. G. Barker, C. J. Glinka, Y. T. Cheng, and P. L. Gammel, J. Appl. Cryst. 33, 793 (2000). For a brief description of the lens system, see the highlight in NCNR

1999 Accomplishments and Opportunities, NIST SP 944, p. 14.

FIGURE 2. Two-dimensional SANS pattern from the sample shown in Fig. 1. Six orders of diffraction are observed due to the high resolution of the lithographi

cally prepared pattern.

NiST CENTER FOR NEUTRON RESEARCH 33
ASYMMETRIC MAGNETIZATION REVERSAL IN

EXCHANGE-BIASED HETEROSTRUCTURES

Exchange bias refers to a shift of the ferromagnetic hysteresis

loop along the field axis, by an amount (see Fig. 1 for

an example.) The bias is a consequence of an exchange interaction

across the interface between dissimilarly ordered magnetic materials, e.g. a ferromagnet and an antiferromagnet (AF). This exchange

interaction induces a unidirectional anisotropy as the AF material

is cooled through its Neel temperature, [1,2]. Exchange bias is

an example of a bulk property whose fundamental origin is attributed to physical processes occurring at the nanometer length-scale.

This phenomenon is not simply a scientific curiosity; it underpins

present-day magnetic recording technology.

FIGURE 1. Magnetization versus applied magnetic field. Exchange bias is the

shift of the ferromagnetic hysteresis loop (in this case to negative H ) from

being centered at //= 0. Measurements displayed in Figs. 2 and 3 were taken,

respectively, near the coercive fields at (a) and (b). Large exchange bias is correlated with asymmetry in the magnetization reversal processes, as noted

in those figure captions.

Read-write heads used with magnetically stored data are based on giant magnetoresistance (GMR) sensors. These sensors

consist of layers of ferromagnetic thin films separated by nonferromagnetic ones. When the the magnetizations in the ferromagnetic layers are all oriented the same way, conduction electrons

pass through them relatively easily, but when the electcons must

cross from films having one orientation to another they encounter more resistance through magnetic scattering. GMR arises when an

external field can change the relative orientations of the magnetization in the films easily. To keep the layers from all reorienting

together in the presence of an external field, some of them must be

pinned. One way to accomplish pinning is exchange biasing.

Despite its technological importance, theoretical models are unable to convincingly explain observations of exchange bias (e.g.

positive exchange bias), and phenomena associated with it. Even

in the simplest experimental systems such as Fe on TMF^ where

TM = Mn or Fe, the asymmetric reversal of magnetization and the

unusual temperature dependence of coercivity are not well understood. Using polarized neutron reflectometry, we recently examined

the magnetization reversal processes of a ferromagnetic Fe film exchange-coupled to twinned AF (TMF^) films as a function of magnetic field [3]. Neutron scattering measurements typical of those from a sample exhibiting large exchange bias are shown in the Figs.

2 and 3 for fields at coercivity on either side of the loop. Spin-flip

(SF) scattering observed on the left hand side of the loop indicates

magnetization reversal via magnetization rotation. Lack of SF scattering on the right hand side is consistent with domain nucleation

(with opposite magnetization) and growth. These two fundamentally

different (asymmetric) reversal processes have distinct neutron scattering signatures. The ability to discern so easily between these

processes sets neutron scattering apart from magnetometry.

Comparisons of measurements like those in the Figs. 2 and

3 taken from many samples, including single crystalline and polycrystalline AF films, lead to the following picture: In the case of samples with twinned AF's, which exhibit large exchange bias, "45°

exchange coupling" is energetically favorable as each AF domain

independently tends to perpendicular coupling but is frustrated due to

34 RESEARCH HIGHLIGHTS
M.R. Fitzsimmons, A. Hoffmann, and C. Leighton and I. K. Schuller

P.C. Yashar Department of Ptiysics Los Alamos National Laboratory University of California - San Diego

Los Alamos, NM 87545 LaJolla, CA 92093-0319

J- Nogues C.F. Majkrzak and J.A. Dura

Departament de Fisica NIST Center for Neutron Research

Universitat Autonoma de Barcelona National Institute of Standards and Technology 08193 Bellaterra, Spain Gaithersburg, MD 20899-8562

• ++

•

• SF

# I

0.1 0.2 0.3 0.4 0.5 0.6 Q[nm-i]

FIGURE 2. Reflectivity of scattered neutrons experiencing no flip in spin

(H- and - -) and for which the spin is flipped (SF) versus Q. These data were

taken at the coercive field on the (a) side of the loop in Fig. 1. The spin-flip scattering observed in this region indicates magnetization reversal through

rotation.

0.1 0.2 0.3 0.4 0.5 0.6 Q[nm-i]

FIGURE 3. Reflectivity of scattered neutrons experiencing no flip in spin

()-+ and - -) versus 0. These data were taken at the coercive field on the

(b) side of the loop in Fig. 1 . No spin-flip scattering was observed, indicatmg

magnetization reversal via domain nucleation and growth.

the twinned microstructure. Furthermore, field cooHng provides an additional unidirectional asymmetry. Therefore, field reduction from positive saturation results in magnetization rotation rather than domain nucleation. This is due to the intrinsic unidirectionality that

hinders formation of domains with magnetization anti-parallel to

the cooling field direction. As the field is reduced from negative

saturation, formation of domains with magnetization parallel to the

initial cooling direction is favored. Hence reversal occurs by domain

nucleation and propagation. For the case of samples with single crystalline (untwinned)

AF's, frustration is lacking; consequently, there is no anisotropy axis

parallel to the cooling field with which unidirectional anisotropy can

be established. In this case, magnetization rotation is always favored

(as evidenced by SF scattering on both sides of the ferromagnetic

hysteresis loop). We note the exchange bias for the single crystal

sample is always small. A clear correlation was observed: samples

with an asymmetric magnetization reversal process exhibit large

exchange bias, while those with symmetric magnetization reversal

process exhibit small exchange bias. By identifying the mechanisms involved in the asymmetry

favoring large exchange biasing in this system, these and related

neutron reflectivity studies point out a direction for the design of

next generation GMR sensors having substantial improvements in magnetic field sensitivity.

This work was supported by the U.S. Department of

Energy, BES-DMS under Contract No. W-7405-Eng-36, grant

DE-FG03-87ER-45332, and funds from the University of California

Collaborative University and Laboratory Assisted Research. REFERENCES

[1] W.H. Meil^lejohn and CP. Bean, Pliys. Rev. 105, 904 (1957).

[2] J, Nogues and Ivan K. Schuller, J. Magn. Magn. Mat. 192, 203 (1998).

[3] M. R. Fitzsimmons, R Yashar, C. Leighton, Ivan K. Schuller, J. Nogues, C.F.

IVIajkrzak, and J.A. Dura, Phys. Rev. Lett. 84, 3986 (2000).

NiST CENTER FOR NEUTRON RESEARCH 35
THE ROLE OF THE GRP/CAMP

PROTEIN COMPLEX IN DNA TRANSCRIPTION

DNA molecules direct the synthesis of specific RNA and protein

molecules. In the early stages of protein synthesis, specific

regions of the DNA (genes) are copied into short strands of RNA

that retain all of the genetic information of the DNA sequence from

which they were copied. The process by which RNA molecules are

synthesized from the coding regions of DNA is known as DNA

transcription. The RNA polymerase enzyme, whose function is to make a RNA copy of a DNA sequence, catalyzes the synthesis of

these RNA molecules. The amount of RNA made from a particular

region of DNA is controlled by gene regulatory proteins that bind to

specific sites on DNA close to the coding sequences of a gene. In

this highlight we describe experiments addressing how a particular gene regulatory protein controls RNA transcription from DNA.

One useful model of such a protein is the cyclic AMP receptor

protein (CRP) of E. coli. Upon binding cyclic adenosine monophosphate (cAMP), CRP undergoes

a conformational change that, in

turn, promotes binding to specific DNA sequences. The CRP/

cAMP complex, upon binding

DNA, produces a bend in the DNA that causes it to wrap

around the RNA polymerase to promote DNA transcription.

A method well suited to

directly study the structure of

proteins and DNA in solution,

where transcription takes place,

is small-angle neutron scattering

(SANS). The radius of gyration,

which can be used to measure conformational changes, and the structure of the molecule in solution can be

determined from an analysis of

the scattered neutron intensity

versus Q.

1.2

1.0

0.8

-

0.6

-

0.4

-

0.2

-

Particularly powerful is the contrast variation technique [1] in which isotopic substitution of D for H in the solvent is routinely

used to change the scattering from a macromolecule without affecting its biochemistry. In the case of a two-component complex such

as CRP/cAMP/DNA (cAMP is considered to be part of the CRP

component), the neutron scattering length density of CRP is quite

different from that of DNA. In this case, the scattered intensity

at each Q value is expressed as the sum of three terms, each of which is the product of an unknown component intensity and a known contrast term. (The contrast is the difference between the

scattering length density of a component and that of the solvent.) Thus, the scattering from the complex in solution can be separated

into component intensities by measuring the scattered intensity of

the complex, 1{Q), at a minimum of three contrasts obtained from

different D,0/H,0 buffer mixtures.

0.0

0.0 20.0 40.0

r(A)

60.0 80.0

FIGURE 1 . The distance distribution functions, P(r), of the CRP component of the CRP/cAIVIP/DNA complex

obtained from the SANS data (•), the energy-minimized x-ray crystal structure (. ) [5,6] and the energy- minimized model structure (—).

36 RESEARCH HIGHLIGHTS
S. Krueger S. Gregurick S. Wang, Y. Shi, F.P. Schwarz B. Wladkowski

NIST Center for Neutron Researcti Department of Ctiemistry Center lor Advanced Researcti in Department ol Ctiemistry

National Institute ol Standards and Technology University ol Maryland, Baltimore County Biotectinology Westem Maryland College

Gaittiersburg, MD 20899 Baltimore, MD 21250 Rocl<ville, MD 20850 Westminister, MD 21157

Recent SANS measurements of CRP/DNA complexes [2] confirmed, in solution, the bending of the bound DNA that was

observed in an early x-ray crystal structure of the complex [3]. However, the Rg value for the complex was larger than that predicted from the same crystal structure. SANS confirmed experimentally that this value does not change with concentration. Thus, the

increase in /?„ is not due to aggregation, but it could result from an

increase in the R„ of the CRP component upon DNA binding. Such

a conformational change would be apparent in the SANS solution measurements: it was not evident in the crystal structure [3]. To obtain the scattered neutron intensity of the CRP component, a contrast variation series of SANS measurements was perDerived from

SANS

FIGURE 2. The top molecule Is the energy-minimized x-ray crystal structure

[5,6] of the CRP(blue)/cAMP(green)/DNA(brown) complex. The bottom molecule

is the energy-minimized model structure which fits the SANS data.

formed on CRP/DNA complexes in 0 %, 15 %, and 70 % Dfi/Hfi

buffer solutions. The Rg values were found to be the same, (28 A

to 30 A), for all three cases. This clearly indicates that the CRP

component is the main reason that ^g^Rp was larger than originally

expected. It was found from the Q behavior of the CRP component

intensity that R^^^^p = 28.5 ± 0.3 A, which is = 6 A larger than the

21.6 ± 0.2 A value observed in solution for CRP alone [4]. It is also

6 A larger than the 22.6 A value predicted for the CRP component

from an energy-minimized x-ray crystal structure of the complex

by Parkinson et al. [5], with cAMP incorporated as in Passner and

Steitz [6]. To model the solution structure of the CRP/DNA complex, the energy-minimized x-ray structure [5,6] was distorted in the regions

thought most likely responsible for the conformational change in CRP upon DNA binding [7]. The distance distribution function,

P{r), was calculated [4] from the energy-minimized distorted conformation and compared to that obtained from the SANS data. As shown in Fig. 1, the P{r) function calculated from the model

structure clearly fits the experimental data better than that from

the x-ray crystal structure [5,6]. A molecular representation of the energy-minimized x-ray crystal structure [5,6] is shown in Fig. 2,

along with the model structure that fits the SANS data. The experimentally observed conformational change in CRP

upon DNA binding may play a role in the enhancement of transcription of DNA by CRP. Perhaps this occurs through its contacts with RNA polymerase that is bound on the DNA at a site adjacent to

the CRP binding site. This is the subject of further ongoing SANS

studies. REFERENCES

[1] H. B. Stuhrmann and A. J. Miller, Appl. Cryst. 11, 325 (1978).

[2] Y. Shi, S. Wang, S. Krueger, and F. P. Schwarz, J. Biol. Chem. 274, 6946 (1999).

[3] D. B. McKay, and T. A. Steitz, Nature 290, 744 (1981).

[4] S. Krueger, I. Gorshkova, J. Brown, J. Hoskins, K. H. McKenney, and F. P. Schwarz,

J. Biol. Chem. 273, 20001 (1998).

[5] G. Parkinson, C. Wilson, A. Gunasekera. Y. W. Ebright, R. E. Ebright, and H. M.

Berman, J. Mol. Biol. 260, 395 (1996).

[6] J. M. Passner and T. A. Steitz, Proc. Natl. Acad. Sci. USA 94, 2843 (1997).

[7] N. Baichoo and T. Heyduk, J. Mol. Biol. 290, 37 (1999).

NIST CENTER FOR NEUTRON RESEARCH 37
POLYMER THIN FILMS UNDER SUPERCRITICAL CO^

In

recent years supercritical fluids (SCFs), materials at temperatures and pressures above their critical values, are being used

in both traditional industry and new advanced technical areas. The

major advantage of SCFs is that their physical properties such

as dielectric constant, density, and solubility parameters, can be

tuned simply by adjusting the temperature and pressure. Especially,

SCFs have also been shown to be effective plasticizers as well as

solvents for numerous polymers. In particular, much attention has been focused on CO, since it becomes supercritical at a moderate

critical temperature and pressure, r_ = 31.3 °C at P^.^ 73.8 bar, and it

is environmentally benign [1].

In spite of its practical importance and numerous studies of

the COj-induced swelling in bulk polymers, fundamental questions

still remain. It is important to understand the interaction

of supercritical CO^lscCO,) that can modify diffusion

coefficient and the glass transition in thin polymer films. The performance of the many applications of thin films is

often dependent on knowledge of the structure and dynam

ics of the interfaces. Therefore, research in this area

Beam-in

will advance understanding of the fundamental physics and applications of polymer thin films. Neutron reflectivity (NR) is used for quantitative determination of the thicknesses, compositions, and interfacial structures of polymer thin films on a nanometer scale. To achieve this under

in situ conditions, we have developed a temperature and pressure

controlled chamber specifically for neutron reflectivity (Fig. 1). The

cell is equipped with two cylindrical sapphire windows. CO, is loaded into the cell by means of a manually operated pressure

generator. Pressurizing and depressurizing cycles up to 1400 bar

are possible. Temperature and pressure stability of the chamber

of ±0.1 °C and ±0.2 %, respectively can be achieved. Due to

the high absorption of neutrons in CO,, the incident and reflected beams passed through the Si substrate with a transmission of

eflon o-ring 0.90 relative to air. It is interesting to note that the background

Gasket scattering from the CO, increases dramatically as the den- hermocouple sity increases at the phase boundary. Hence the supercritical transition point can be indepenHeating bands Gently monitored with high accuracy.

Beam-out

Sapphire window Si Substrate CO2 reservoir Quartz spacer

FIGURE 1 . Cross-sectional view of the supercritical CO2 chamber for neutron

reflectivity measurements.

38 RESEARCH HIGHLIGHTS
K.Shin, T.Koga, Y.Seo, Y.Zhang, M.Rafailovich, and J.Sokolov

Department of Materials Science and Engineering

State University of New Yorl< at Stony Brool< Stony Brook NY, 11794-2275

S.K.Satija NIST Center for Neutron Researcfi National Institute of Standards and Tecfinology

Gaithersburg, MD 20899-8562

In this study we have successfully performed NR measurements of deuterated polystyrene (d-PS) thin films in COj at P <

700 bar (Fig. 2). The results show an anomalously large swelling

maximum (AV/V » 25 %) which occurs only at the supercritical

fluid/gas phase boundary. Atomic force microscopy confirmed the swelHng is uniform throughout the films and does not produce large

voids. Such a swelling maximum at the supercritical fluid/gas phase

boundary has never been seen in bulk PS-CO, mixtures. In addition,

an isobaric experiment at 79 bar showed that the same swelling

behavior did not appear at the phase boundary between the liquid

and supercritical fluid CO, phases. At this point we can only speculate that the anomalous swell- mg behavior may be related to the higher order nature of the

gas/supercritical fluid transition that is accompanied by larger density flucmations than the first-order liquid/supercritical fluid transition. Experimentally these fluctuations are clearly seen by the sharp

increase in background scattering from the CO, at the transition

boundary. Adsorption of CO, into the viscous polymer film may

suppress these fluctuations thereby lowering the energy of the system. This effect was further investigated by observing the swelling

of the d-PS film as a function of temperature at P = 79 bar (Fig. 3.) Recendy we have expanded our research by measuring chain

mobility in bilayer polymer films of d-PS and hydrogenated PS

(h-PS). We have used secondary ion mass spectrometry and NR to measure the diffusion coefficient as a function of pressure, temperature and molecular weight. This work established that swelling at

the phase boundary is accompanied by an increase in interdiffusion between the polymer layers and a large decrease in the PS glass

transition temperature. These results show that scCO, can potentially

be used to process multi-component thin polymer films that may

otherwise not be miscible. Potential applications are in the areas of

graded index of refraction waveguides and lower dielectric constant

films for use in microelectronic devices. REFERENCES

[1] M.A. McHugh and V.J. Ki'ukonis, Supercritical Fluid Extraction, 2nd Ed., Butterworth-Heinemann, 1993.

0.02

1 bar

86 bar J> 140 bar

0.04

q.(1/A)

0.06

^ 0.05

0.00

FIGURE 2. Representative reflectivity data for the first pressurization process

at r= 36 °C. The lines are the best-fit results of the model to the observed

density profiles. Swelling is evident in the change of the period of the fringes.

Inset: a schematic phase diagram of CO^ near critical point. The vertical line

at 36 °C in the inset is the isotherm along which data were taken at pressures

of 1,86, and 140 bar.

FIGURE 3. Temperature dependence of the swelling of polystyrene at P = 79

bar (filled circles). Open circles show the averaged background intensity as a function of temperature.

NIST CENTER FOR NEUTRON RESEARCH 39
COLD NEUTRON DEPTH PROFILING OF

LITHIUM BATTERY MATERIALS

Aspart of a continuing collaboration between NIST and Tufts

University, we have employed cold neutron depth profiling

(NDP) to measure elemental concentrations versus depth for several

lithium ion battery materials. One goal is to rationally design the thermo-mechanical properties of amorphous lithium phosphorous

oxynitride (lipon, a solid ionic conductor), particularly the thermal

stress (thermal expansion coefficient). A part of this study is to relate

the resulting thermal stress to starting composition and temperature

of evaporant, and of the composition and pressure of the background

gas during deposition. We are also studying LiCoO, films (a material

that can be used as an electrode in batteries) to determine if the

ion beam assisted deposition process used has the capability of

controlling not only the degree of crystallinity and orientation of

crystallites, but also of the Li/Co ratio. The NIST cold neutron depth profiling instrument and technique have been described previously [1]. The technique of neutron

depth profiling (NDP) permits the determination of depth profiles in

thin films up to a few micrometers for several light elements. The

most readily analyzed elements are lithium, nitrogen, and boron. We have previously reported measurement of lithium mobility in

electrochromic devices [2]. The lithium depth profiles are based on

the measurement of the energy of alpha particles and/or tritons from

the ^Li(n,a)-''H reaction. Nitrogen depth profiles are based on the measurement of the energy of protons from the '''N(n,p)'''C reaction. Samples are placed in a beam of cold neutrons, and the emerging

particles are intercepted by surface barrier detectors that measure

their number and energy. Comparing the emission intensity with

that of a known standard leads to quantitative determination of the

lithium and nitrogen concentrations. Moreover, the emitted charged

particles lose energy as they exit the film; this energy loss provides

a direct measurement of the depth of the originating lithium nucleus. A great advantage of the NDP technique is that it is non-destructive,

which allows repeated observations of the concentrations under different conditions. When combined with other techniques, e.g., activation analysis, ratios to other constituents can be determined.

Upon depth distribution

-0.20 0.00 0.20 0.40 0.60 0.80 1.00

depth, \im

FIGURE 1 . Depth profiles of lithium and nitrogen for two different lipon samples.

Table I

Sample Li/N Ratio Thickness, |xm

Y243 4.46 0.7

Y232 4.39 1.5

Y239 1.63 0.4

Y245 3.1 0.6

Figure 1 gives an example of profiling results using the NDP

technique. Shown here are profiles for two lipon samples manufactured under different conditions. The elemental concentrations in atoms/cm^ are presented as a function of depth. Because the alpha

particle loses energy at a greater rate than the proton, the resolution

for the lithium profile is better than that for nitrogen. One observes

that the sample Y245 has a much more uniform distribution of

lithium than sample Y239. By integrating the areas under the curves, one obtains the total concentration of lithium and nitrogen, respectively, and therefore the ratio of the two in the sample. Table I gives

measured lithium/nitrogen ratios thus obtained and the corresponding thicknesses of four lipon samples.

40 RESEARCH HIGHLIGHTS
G.P. Lamaze, H.H. Chen-Mayer, and

D.A. Becker

Chemical Science and Technology Laboratory

National Institute of Standards and Technology

Gaithersburg, MD 20899-8395

F. Vereda, A. Gerouki, N. Clay, P. Zerigian,

T. Haas, and R.B. Goldner

Electro-Optics Technology Center

Tufts University Medford, MA 02155

im

LiCoO,

E

o

ca o

o

o

14

12

10

8

6

4

2

0

- --£r-Z57a, B

^ Z57a, T

i

^ i i

i i i

!

! v>l ^

i .j_jyn-^ V\ ^

i ! i

1

1 1 1 1 II II 1 1 1 1 1 n^^fc

-0.10 0.00 0.10 0.20 0.30

depth, \im

0.40 0.50 0.60

FIGURE 2. Typical lithium depth profiles of two LiCoGj samples.

Table II

Sample Lithium

(at/cm2)

Cobalt

(at/cm2)

Li/Co RatioRatio Uncertainty

(%)(1a)

Z57a,T 4.9x1017 7.0x10" .70 3.5

Z57a,B 2.2x10" 7,0x10" .31 3.5

Z57b,T 4.8x10" 7.0x10" .68 3.5

Z57b,B 1.9x10" 7.0x10" .27 3.5

Z59 9.4x10" 7.6x10" 1.25 3.5

To obtain information on other isotopes that are not measurable by NDP, a combination of techniques is employed. In the

following example the ratio of lithium to cobalt in two thin film LiCoO, samples is determined. The lithium concentration is deter- mined by NDP, as described above; and the cobalt concentration

is determined by instrumental neutron activation analysis (INAA).

Figure 2 gives lithium depth distributions from NDP measurement

for two thin films of LiCoO,. The integral under the curves gives

the total amount of lithium in the film. After the depth distributions

were obtained, the samples were encapsulated in polyethylene "rabbits" for irradiation in the core of the NIST reactor. The total

cobalt concentration was then determined by INAA in which the ^°Co gamma decay intensity was measured and compared with a

standard. Table II gives the lithium and cobalt atom area density

obtained from NDP and INAA respectively, as well as the lithium/

cobalt atom ratios for these and other samples. The INAA technique does not provide any depth information, so that the ratio values

listed in the table are for the average over the entire depth. To summarize, depth profiles of two different lithium ion battery materials have been measured. For the Upon sample, profiles were obtained for lithium and nitrogen as well as the total quantity

of each of these elements in the film. To date, an insufficient number

of samples have been measured to obtain a good correlation with

the physical properties of the films. We are also investigating the

possibilities of measuring Li/P ratios of both starting materials and

resulting films by combining NDP with RNAA for phosphorous. For the lithium cobalt oxide sample, the NDP technique was

combined with INAA to determine the ratio of lithium to cobalt in

the samples. Although further work is needed to better quantify the

relative evaporation rates of lithium and cobalt, it has been demonstrated that the measured Li/Co ratio varies in direct proportion to

the relative evaporation rates of lithium and cobalt, as anticipated.

Furthermore, the results indicate that the Li/Co ratio can be controllably varied from being less than one to greater than one. REFERENCES

[1] R. G. Downing, G. P. Lamaze, J. K. Langland, and S. T. Hwang, NIST Journal of

Research, 98, 109(1993),

[2] G. R Lamaze, H. H, Chen-Mayer, A, Gerouki, and R. B, Goldner, Surf. Interface Anal, 29, 637 (2000).

NiST CENTER FOR NEUTRON RESEARCH 41
SERVING THE SCIENTIFIC AND

TECHNOLOGICAL COMMUNITIES

The role of the NCNR as a national user facility has expanded

significantly over the past year, as the final few instruments

envisioned in the original cold neutron project have become operational. The Disk-Chopper Spectrometer, the Filter-Analyzer Neutron

Spectrometer, the High Flux Backscattering Spectrometer, and the Neutron Spin-Echo spectrometer now permit U.S. scientists to carry

out neutron spectroscopy with greatly enhanced resolution and sensitivity. In addition the new thermal perfect-crystal diffractometer

small angle neutron scattering instrument (USANS) has been commissioned this year, expanding the length scale available by this

technique to 10^ nm. User experiments show a steadily increasing

diversification in subject area and technique, enabled by the new

instruments. We anticipate that the trend will continue over the next few proposal cycles. (See the highlights on USANS, FANS, and

DCS in this issue. The 1999 NCNR report featured a highlight on

the NSE.)

User participation over the past 14 years shows continuing

growth (see Fig. 1 ). The NCNR currently accommodates more

than half of all neutron users in the United States. It has assumed

greater importance to the neutron user community this year with

1800

1600

1400

1200

1000

800

600

400

200

In FY 2000 Research Participants were from: 21 IMIST Divisions and Offices 34 U.S. Government Laboratories

115 U.S. Universities 50 U.S. Industrial Laboratories

90 92 94 96 98 2000

FIGURE 1: Research Participants at tlie NCNR.

the announcement of the permanent shutdown of the High Flux

Beam Reactor at Brookhaven National Laboratory. As the Spallation Neutron Source is being built at Oak Ridge, the NCNR continues to be the Nation's premier facility for providing neutrons to the U.S.

research community.

THE NCNR USER PROGRAM

Researchers may obtain use of NCNR neutron beam instruments

in several ways, the most direct being through the formal proposal

system. Approximately twice a year, a Call for Proposals is issued.

After a thorough review process by external referees and by the NCNR Program Advisory Committee (PAC), approved proposals are

allocated beam time. The PAC is a panel of distinguished scientists

with expertise across a broad range of neutron methods and scientific disciplines. It is the body primarily responsible for proposal

review and recommending user policies for the NCNR, working

closely with the Center's Director and staff. Its current membership

includes Sanat Kumar (Penn State University, chair), Robert M.

Briber (University of Maryland), Michael K. Crawford (DuPont),

Dieter K. Schneider (Brookhaven National Laboratory), Thomas P.

Russell (University of Massachusetts), Sunil K. Sinha (Argonne

National Laboratory), Laurence Passell (Brookhaven National

Laboratory), and Gabrielle G. Long (NIST). At the recent PAC meeting in May 2000, the PAC considered

7 1 proposals for SANS and reflectometry, in addition to 43 for

inelastic neutron scattering. Although we expect that both categories

will see increased user demand in future proposal rounds, the latter

area is likely to see more growth, since the new inelastic scattering

spectrometers will offer capabilities that in aggregate have not been

available previously at U.S. neutron facilities. THE CENTER FOR HIGH RESOLUTION

NEUTRON SCATTERING

Several NCNR instruments are supported by the National Science

Foundation (NSF) through the Center for High Resolution Neutron

Scattering (CHRNS), a very important component of the user program. The instruments include a 30 m SANS machine, the SPINS

triple-axis spectrometer, and USANS. Approximately 40 % of the

instrument time allocated by the PAC goes to experiments carried

out on CHRNS instruments. In the near future, another SANS diffractometer, the 8 m machine on neutron guide NG-1, which is

presently used primarily for NIST programmatic research, will be

42 SERVING THE SCiENTiFiC AND TECHNOLOGICAL COMMUNITIES
upgraded to a more powerful 9 m instrument with a new detector, and made available to users. The NSF is currently reviewing a proposal to further expand the scope of CHRNS, so that it will encompass several of the newer cold neutron spectrometers. Including

these instruments in the CHRNS project will provide maximal technical support and accessibility to the user community.

SIXTH ANNUAL SUMMER SCHOOL

The NCNR held its annual Summer School on Neutron Scattering on June 5-9, 2000. The course this year focused on the complementary techniques of SANS and neutron reflectometry (NR) and was attended by a group of 32 graduate students and postdoctoral

fellows, predominantly from university chemical engineering and

materials science departments. By devoting an entire week to just two techniques, it was possible to cover both theoretical and practical aspects, as well as appHcations, in some depth. Sixteen NCNR

staff members led the participants through lectures, demonstrations

V and hands-on experiments at the NCNR's two 30 m SANS instru- ments and two reflectometers. Included for the first time in this

year's course were demonstrations of newly developed computational tools for planning and simulating SANS and NR experiments now accessible through the NCNR Web site. The final day of the course consisted of parallel lecture sessions in the morning on applications of the two techniques drawn

from recent research in polymer science, complex fluids, magnetism, and structural biology. The course closed with a session in which representatives from each team presented their experimental

results to the whole class and staff, which prompted several lively

discussions. Comments received throughout the week and on the

course evaluation forms indicated that the course was successful

in enabling the attendees to assess the applicability of neutron scattering to their own research interests. As in the past, this summer

school was jointly sponsored with the National Science Foundation,

which provided financial assistance to many of the university participants.

FIGURE 2: Participants gain liands-on experience in SANS measurements at the 6tli annual summer school on neutron scattering, June 5-9, 2000

COLLABORATIONS

Direct collaborations on specific experiments remain a common way

for users to pursue their ideas using NCNR facihties, accounting for

approximately half of the number of instrument-days. The thermalneutron triple-axis spectrometers are mainly scheduled in this way. Most of the time reserved for NIST on these and all other NCNR

instruments is devoted to experiments that are collaborations with non-NIST users. Collaborative research involving external users and

NIST scientists often produces results that could be not obtained

otherwise. Another mode of access to the NCNR is through Participating

Research Teams (PRTs). In this case, groups of researchers from

various institutions join forces to build and operate an instrument.

Typically, 50 % to 75 % of the time on the instrument is then

reserved for the PRT, and the remaining time is allocated to general

user proposals. For example, a PRT involving ExxonMobil, the

University of Minnesota, and NIST cooperates on the NG-7 30 m

SANS instrument. Similar arrangements involving other PRTs apply

for the horizontal-sample reflectometer, the high-resolution powder

diffractometer, the filter-analyzer spectrometer, and the neutron spinecho spectrometer.

NiST CENTER FOR NEUTRON RESEARCH 43
INDEPENDENT PROGRAMS

There are a number of programs of long standing located at the NCNR that involve other parts of NIST, universities, industrial laboratories, or other government agencies.

The Polymers Division of the Materials Science and

Engineering Laboratory has two major program elements at the NCNR. In the first, the purpose is to help the U.S. microelectronics

industry in addressing their most pressing materials measurement

and standards issues. In today's ICs and packages the feature size on a chip is ever shrinking, approaching 250 nm, while the size of

a polymer molecule is typically 5 nm to 10 nm. As feature size

shrinks, the structure and properties of interfaces play an increasingly important role in controlling the properties of the polymer

layers used in interconnects and packages. NIST scientists use both

neutron reflectivity and other neutron scattering methods to characterize polymer/metal interfaces with regard to local chain mobility,

moisture absorption, glass transition temperature, and crystalline

structure.

In the second program element, the objective is to understand

underlying principles of phase behavior and phase separation kinetics of polymer blends, both in the bulk and on surfaces, in order

to help control morphology and structure during processing. SANS

and reflectivity measurements in equilibrium, in transient conditions,

and under external fields, provide essential information for general

understanding as well as for specific application of polymer blend/

alloy systems. Customers include material producers and users,

ranging from chemical, rubber, tire, and automotive companies, to

small molding and compounding companies. The focus of research on polymeric materials includes commodity, engineering and specialty plastic resins, elastomers, coatings, adhesives, films, foams,

and fibers. The ExxonMobil Research and Engineering Company is

a member of the Participating Research Team (PRT) that operates,

maintains, and conducts research at the NG-7 30 m SANS instru- ment and the recently commissioned NG-5 Neutron Spin Echo

Spectrometer. The mission is to use those instruments, as well as

other neutron scattering techniques, in activities that complement

research at ExxonMobil's main laboratories as well as at its affiliates' laboratories around the world. The aim of these activities is

to deepen understanding of the nature of ExxonMobil's products

and processes, so as to improve customer service and to improve

FIGURE 3: PAC substitute Bill Hamilton (ORNL), members Larry Passell (BNL) and

Dieter Schneider (BNL), and PAC Chair, Sanat Kumar (Penn State U.) share a

lighter moment while considering proposals for beam time at the NCNR.

the return on shareholders' investment. Accordingly, and taking full advantage of the unique properties of neutrons, most of the experi- ments use SANS or other neutron techniques to study the structure and dynamics of hydrocarbon materials, especially in the fields

of polymers, complex fluids, and petroleum mixtures. ExxonMobil

regards its participation in the NCNR and collaborations with NIST

and other PRT members not only as an excellent investment for the company, but also as a good way to contribute to the scientific health

of the Nation. The Nuclear Methods Group (Analytical Chemistry

Division, Chemical Science and Technology Laboratory) has as its

principal goals the development and application of nuclear analytical

techniques for the determination of elemental compositions with

greater accuracy, higher sensitivity and better selectivity. A high

level of competence has been developed in both instrumental and

radiochemical neutron activation analysis (INAA and RNAA). In

addition, the group has pioneered the use of cold neutron beams

as analytical probes with both prompt gamma activation analysis

(PGAA) and neutron depth profiling (NDP). PGAA measures the

total amount of a particular analyte present throughout a sample

by the analysis of the prompt gamma-rays emitted during neutron

capture. NDP, on the other hand, determines concentrations of several important elements (isotopes) as a function of depth within the

44 SERVING THE SCIENTIFIC AND TECHNOLOGICAL COMMUNITIES
first few micrometers of a surface by energy analysis of the prompt

charged-particles emitted during neutron bombardment. These techniques (INAA, RNAA, PGAA, and NDP) provide a powerful combination of complementary tools to address a wide variety of analytical problems of great importance in science and technology, and

are used to help certify a large number of NIST Standard Reference

Materials. During the past several years, a large part of the Group's

efforts has been directed towards the exploitation of the analytical

applications of the guided cold-neutron beams available at the NIST

Center for Neutron Research. The Group's involvement has been

to design and construct state-of-the-art cold neutron instruments for

both PGAA and NDP and provide facilities and measurements for

outside users, while retaining and utilizing our existing expertise in INAA and RNAA.

The Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration (FDA), directs and maintains a neutron activation analysis (NAA) facility at the NCNR. This facility

provides agency-wide analytical support for special investigations

and applications research, complementing other analytical techniques used at FDA with instrumental, neutron-capture prompt-gamma, and radiochemical NAA procedures, radioisotope x-ray fluorescence spectrometry (RXRFS). and low-level gamma-ray detection.

This combination of analytical techniques enables diverse multi- element and radiological information to be obtained for foods and

related materials. The NAA facility supports agency quality assurance programs by developing in-house reference materials, by characterizing food-related reference materials with NIST and other

agencies, and by verifying analyses for FDA's Total Diet Study

Program. Other studies include the development of RXRFS methods

for screening foodware for the presence of Pb, Cd, and other potentially toxic elements, use of instrumental NAA to investigate bro- mate residues in bread products, and use of prompt-gamma NAA to

investigate boron nutrition and its relation to bone strength.

The Neutron Interactions and Dosimetry Group (Physics

Laboratory) provides measurement services, standards, and fundamental research in support of NIST's mission as it relates to neutron

technology and neutron physics. The national and industrial interests

served include scientific instrument calibration, electric power production, radiation protection, defense nuclear energy systems, radiation therapy, neutron radiography, and magnetic resonance imaging.

The Group's activities may be represented as three major

activities. The first is Fundamental Neutron Physics including magnetic trapping of ultracold neutrons, operation of a neutron interfer- ometry and optics facility, development of neutron spin filters based on laser polarization of %e, measurement of the beta decay lifetime

of the neutron, and investigations of other coupling constants and

symmetries of the weak interaction. This project involves a large

number of collaborators from universities and national laboratories. The second is Standard Neutron Fields and Applications utilizing both thermal and fast neutron fields for materials dosimetry

in nuclear reactor applications and for personnel dosimetry in radiation protection. These neutron fields include thermal neutron beams,

"white" and monochromatic cold neutron beams, a thermal-neutron- induced ^-^^U fission neutron field, and ^^^Cf fission neutron fields,

both moderated and unmoderated.

The third is Neutron Cross Section Standards including experimental advancement of the accuracy of neutron cross section standards, as well as evaluation, compilation, and dissemination of these

standards.

Several universities have also estabhshed long term programs

at the NCNR. The University of Maryland is heavily involved in

the use of the NCNR, and maintains several researchers at the facility. Johns Hopkins University participates in research programs in

solid-state physics and in instrument development at the NCNR. The

University of Pennsylvania is working to help develop biological

applications of neutron scattering. It is also participating in the second stage construction of the filter analyzer neutron spectrometer,

along with the University of California at Santa Barbara, DuPont,

Hughes, and Allied Signal. The University of Minnesota participates in two PRTs, the NG-7 30 m SANS and the NG-7 reflectometer. The University of Massachusetts also participates in the latter PRT

NIST CENTER FOR NEUTRON RESEARCH 45
REACTOR OPERATION AND ENGINEERING

The reactor operated for 198 full power (20 MW) days during

the past year or 54 % of real time that is equivalent to 77 %

of the maximum available operating time. Routinely, the reactor

is scheduled to operate on a seven week cycle, seven times a year. Each operating cycle includes 38 days on-line and 11 days shut- down for refueling, routine maintenance, and surveillance tests. This

year, several major tasks became due and required additional shut- down time. Included among these are two shipments of spent fuel; replacement of the shim arm assemblies which required removal of

the entire core and took only one month, half of that previously;

and major modification to the refueling system projected to take two months which was completed in five weeks. In addition, corrective maintenance of the thermal shield and the thermal column

coohng systems, refurbishing of the existing cooling tower to assure

uninterrupted operation for at least two more years, and finally the

biennial retraining, re-examination and requalification of all licensed

operations personnel were conducted. The major engineering effort the past year was the design and

specification of a completely new plume-abatement cooling tower

to be installed adjacent to the existing one. (Figure 1 compares

examples of abated and non-abated cooling towers.) As well as being a larger capacity, more effective and more efficient system,

the new tower eliminates vapor plumes down to -12 °C ambient.

Construction of the new tower basin began in late September 2000

and should be completed before the end of the year. Fabrication of

the tower is underway and scheduled for completion in the spring

of 2001 to be followed by on-site installation, expected to take approximately four months. No reactor shutdown will be required

during this period. The reactor will have to be shut down only for

final hookup of electrical, controls, and piping connections and for

acceptance and performance testing.

FIGURE 1. No discernible cloud is emitted by the plume-abated cooling tower shown on the left compared to the plumes emerging from the non-abated towers on the right.

Preparations for reactor re-licensing in 2004 for an additional 20 years are proceeding. They include preparation of an updated

safety analysis report including seismic evaluation, an environmental report and impact statement, technical specifications and bases,

operator requalification program and emergency and security plans.

In-service inspections of reactor internals and ultrasonic testing of

the primary cooling system plus upgrade of older systems and

components will be needed in support of the application for license

renewal. Many of the upgrades have already been completed or are

in progress. Among the major upgrades planned over the next few

years are complete replacement of the nuclear instrumentation panel

and associated safety and control systems, complete replacement of

the electrical power systems and associated switch gear and replace- ment and upgrade of the reactor emergency power supply systems.

46
INSTRUMENTATION DEVELOPMENTS

A LOW BACKGROUND DOUBLE FOCUSING

NEUTRON MONOCHROMATOR

Work continues on the development of a low background double

focusing monochromator which was described in the 1999 NCNR

report. The actively controlled double focusing monochromator consists of an array of 315 pyrolytic graphite crystals mounted on 21

thin aluminum blades (see Fig. 1). When buckled, each variable

thickness blade conforms in shape to an arc of constant radius

providing active vertical focus control. Horizontal focus is accomphshed by independently controlling the rotation of each blade. The design and choice of materials for the system reduces

scattering from the supporting structure, a problem common to traditional lead-screw and lever controlled monochromators. Structural

material in the beam is limited to the 21 blades and three thin walled aluminum posts. The 315 crystals are accurately suspended with

only 630 g of structural material in the beam's direct line of sight. An engineering mock-up of the focusing system was con-

, structed (see Fig. 2a). This three-blade version of the full-scale

21 -blade unit was used to study blade performance, develop control

software, quantify horizontal and vertical focus performance, and

test mechanical and electrical system components. Figure 2b shows

an optical test of vertical focus performance using the mock-up. The

FIGURE 1. Rendered image of the low background doubly focusing monochromator.

FIGURE 2. Three blade mockup of the double focusing monochromator focusing system, (a) Blades are shown buckled to an arc of a 1 m radius circle,

(b) Vertical focusing is optically verified by focusing a white point source onto

a screen.

three blades are covered with reflective mirrors and illuminated with

a white point source. The reflected image is focused onto a screen. Imaging tests such as this, as well as mechanical measurements,

have verified that errors in blade shape are negligible compared to

contributions due to crystal mosaic over the focal range of interest.

Similar optical tests have been used to verify the horizontal focus performance.

The full-scale unit is currently under construction. When completed, the 1300 cm^ monochromator will be the heart of the new

cold neutron spectrometer under development at the NCNR. It is expected to provide an intense monochromatic neutron flux with 0.1 < AE < 0.5 meV and AQ = 0.1 A ' yielding a peak flux of order 1.0 X 10^ n/craVs, higher than any currently available worldwide. This new instrument will be ideal for studying materials with excitations having a low characteristic velocity. The enhanced sensitivity will

enable inelastic neutron scattering studies of smaller sample size and will provide dynamic information of unprecedented detail when

large samples are available.

NiST CENTER FOR NEUTRON RESEARCH 47
THE BT-7 THERMAL TRIPLE AXIS

ANALYZER/DETECTOR SYSTEM

As part of the modernization of the thermal neutron spectrometers

a new triple-axis instrument is being designed for the BT-7 thermal beam port. For the analyzer portion of this machine several different

types of systems have been proposed. One type is a horizontally

focused pyrolytic graphite analyzer system shown in Fig. 3. The

analyzer crystal system consists of 13 pyrolytic graphite blades,

each 2 cm wide and 15 cm high, with either an individual detector

for each of the 13 blades, or a position-sensitive detector using all

the blades at once.

This is the modem equivalent of our present analyzer systems,

and is expected to be the workhorse for the new thermal triple axis

instruments. The blades of the analyzer can be freely rotated by

360 degrees and individually positioned, while the entire unit can be

rotated as a whole to achieve the desired focusing condition. Each

blade can then be matched with a detector that is capable of being

positioned individually by a stepper motor on a circular track around

the analyzers. A straight-through beam monitor is incorporated into

the shielding behind the analyzer crystals to continuously monitor

the flux of neutrons entering the analyzer system. A separate diffraction detector is also provided, which can be moved in front of the

analyzer if the energy-integrated signal is to be measured.

The general design philosophy is to make the instrument as

user friendly as possible while still meeting all the desired operating

criteria. These include a built-in magnetic guide field for polarized

beam operation; and various beam defining systems such as collimators, beam apertures, spin flippers, and filters. Ease of exchanging beam collimators before and after the analyzer crystals is an

important design feature that presents an engineering challenge.

Extracting the wiring from all the moving detectors and motors

inside the system will also be a technical challenge.

A second type of analyzer system will consist of a series of up

to 30 individual and isolated analyzer/detector systems. Other analyzer options, to be developed in the future, include incorporating

a velocity selector into the analyzer system, and developing a "conventional" double-focusing analyzer with a single, well-shielded

detector. THERMAL NEUTRON PROMPT GAMMA-RAY

ACTIVATION ANALYSIS (PGAA) FACILITY

AT VT-5.

The vertical beam tube VT-5 thermal neutron PGAA facility

is being upgraded through a collaboration of members of the NCNR, the Nuclear Methods Group, and the U.S. Food and Drug

Administration. The current facility consists of an internal neutron-collimating beam tube and shutter assembly, an external beam

tube, sample chamber, a beam stop, and a gamma-ray detection system. All components except the

internal beam tube and shutter assembly will be replaced and

a sapphire filter installed in the

shutter assembly. The new components will be designed to

reduce background count rates and improve detection limits. The external components will be

constructed as a single unit to

simplify removal and re-assembly of the instrument to make

room for reactor refueling.

FIGURE 3. Horizontally focused pyrolytic graphite analyzer system for the BT-7 thermal triple-axis spectrometer. 48
FIGURE 4. Andrzej Rajca (left, University of Nebraska) and NCNR's Sung-Min

Choi load a sample under special conditions. For this SANS experiment, the sample had to be kept below 170 K from storage in liquid nitrogen to top- loading into the pre-cooled cryostat. The transfer was performed in a helium atmosphere using a glove bag in order to prevent water condensation on the

V sample cell surface.

A cylindrical sapphire filter 5.3 cm long (4.3 cm diameter) was added to the shutter. This modification reduced the number of

fast neutrons by a factor of five and greatly reduced the low-energy

gamma-ray background. The gamma-ray background measured at

the perimeter of the apparatus has decreased by a factor of two and

the peak-to-background ratios for gamma-ray energies below 500

keV increased by a factor of two to three. The design of the new system is complete. The steel component of the old beam stop will be replaced by aluminum to eliminate

iron capture gamma-ray background. The external beam tube wiU be

evacuated to minimize neutron scattering and capture in air and will

be constructed from aluminum tubing lined internally with lithoflex

to eliminate the background for boron determinations. The detection system will consist of a 40 % (relative efficiency) germanium detector with a bismuth germanate Compton suppression system. The new system will decrease analysis times and improve detection for most elements determined. SAMPLE ENVIRONMENT TEAM

Fiscal year 2000 marked the creation of a new Sample Environment

Team, dedicated to providing a central resource for the sample

environment needs of neutron researchers. This team provides a

single contact point to resolve any issue related to the sample conditions during an experiment, such as temperature, pressure, magnetic

field, electric field, or in situ measurements. The scope of this team includes sample preparation and mounting, equipment schedul

ing, special equipment configurations, operational procedures, provi

sion of necessary resources, sample storage, and equipment repair. Figure 4 shows researchers loading a sample. In this case a difficult SANS experiment was made possible by the team working with

the researchers to choose the appropriate sample environment equip ment and operating procedures.

The most visible change during FY2000 is in the high-bay

sample preparation area at the NCNR. This area was extensively

remodeled to provide more workspace, greater ease of use, more

convenient preparation of cryogenic equipment, and better access

to sample storage. Additionally, extensive documentation is now

available for the most widely used sample environment equipment,

the closed-cycle helium refrigerators. This documentation details individually-measured operating characteristics, sample mounting

information, temperature sensor data, and operating guidelines.

Significant new equipment acquired for the user community in FY2000 is Usted in Table 1.

TABLE 1 . Significant sample environment purchases during FY2000.

100 mm access top-loading 1.5 K to 300 K, dedicated to helium cryostat time-of-fiight spectrometer

70 mm access top-loading 1.5 K to 300 K, general use

helium cryostat

Seven additional sample Provide for faster sample changes

probes for 50 mm, 70 mm, and and specialized needs such as 100 mm access top-loading gas handling helium cryostats

Closed-cycle helium refrigerator lOKto 350 K, dedicated to backscattering spectrometer

Closed-cycle helium refrigerator lOKto 350 K, general use

Electromagnet 0-0.7 Tesia, dedicated to

vertical reflectometer

Thirty indium-sealing Mounting of powder samples and sample cans single crystal samples

Six temperature controllers Multiple sensor capability, PID control

Nine turbopumps 10-' mbar base pressure Two large rotary vane pumps 10 '' mbar base pressure

NIST CENTER FOR NEUTRON RESEARCH 49
RESEARCH TITLES

MATERIALS SCIENCE/CRYSTALLOGRAPHY

Ab-initio Structure Solution of Complex Oxides Using Neutron and

X-ray Powder Diffraction Data

P. Wooclwardi25 and P. Underwood'29 A Bond-Valence Analysis of the Structure of YBa^FejOg

I, Natali Sorai" and A. Santoro'os Aerogels Investigated by SANS with Contrast Masking Solutions

C. Merzbacheroi, M. Anderson"^, V. Cepak'01, and J. G. Barken"5 Cation Ordering in Magnetically Frustrated Pyrochlores

M. A. Green"", T. Fenneli"', and S. Bramwelh"' Characterization of Ag and Mixed Li/Ag Faujaslte Zeolites Using Neutron Diffraction

N. Hutson^c^, R. Yang2»2, B. A. Reisnercs, and 8. H. Toby^fs Chemical Ordering in Ni-Mn-Ga Heusler Alloys

R. Overholser"9, M. Wuttig'^', and D. A. Neumann'»5 Comparison of Residual Stress Measurement Techniques

T, Gnaupel-Herold"9 105, P C. Brand^os, H. J. Praskios, s. Spooneri2', B. Pardue'6', D. Nelsonise, and S. FossTM 'CONV and 'STRESS': New Codes for Data Reduction in Neutron

Diffraction Residual Stress Measurements

P C. Brand'05 and T. Gnaupel-Heroldi^a^i* Crystal Chemistry of Protonic Centers in Zeolites

D. H. Olson2i» and B. H. Tobyi"5 Crystal Structure of Ba^CaCu^OgiCOj)

Q. Z. Huangi99 '»5and F. Izumi'ss

Crystal Structure of Dehydrated LaD-LSX

D. H. Olson2'", B, A. Reisner*, and B. H. Tobyios

Crystal Structure Determinations of the CeMnOj Compound

W.-C. Li94 Defect Structure of (Cu.ZnjlnSOj

B. A. Reisner'05, M. Knox"8, A. Stacy^TM, and G. Ron^s The Development of Capabilities for the Determination of Residual

Stress on the Mesoscale

H. J. Praskios, p C. Brand'*, T. Gnaupel-Herold'^i*, D. Balzar'", D. Hurley"2, and G. Alersi'2 Development of a Standard for Residual Stress Measurements as Part

of VAMAS

T. Gnaupel-Heroldi99 i"^ P C. Brando's, hi. J. Praskios, and G. A. Wester^e

Diffraction Elastic Constants for Arbitrary Specimen and Crystal

Symmetries: Theory and Practical Consequences

T. Gnaupel-Herold'» and H. J. Prask'* Distribution of Hydrogen in LaNig and LaNi5„Sn,

B. Fultz'8, C. K. Witham'8, T. Udovic'os, and R. Bowman's

Effect of Annealing on ZrO^ Phase Composition

J. K. Stalick'05 and J. Ilavsky29 The Effect of Texture on Elastic Constants

H. Sitepu'".'05.i48_ T. Gnaupel-Herold"9 '05^ j Matejicekw, R. Fields'", and H.

J. Prask'05 The Effect of Texture on Rietveld Refinement of Powder Diffraction Data of Molybdite and Calcite

H. Sitepu's^ 'os. '"8, T. Gnaupel-Herold'55.105, and H. J. Prask'os Ethylene Sorption by Copper Aluminum Chloride

R. Sullivan'2', J. Martin'2', H. Liu'", and C. Grey'" Exploration of Fe Disproportionation in BajFeOg

B. A. Reisner'°5, J. Delattre'TM, and A. Stacy'TM Formation of Titanium Mesoporous Materials P D. Butler'fs.'"

Grazing Incidence SANS From Plasma Sprayed Coatings

A. J. Allen'»9and H. Boukari'°9 Hybridized Epoxy-Silicate Nanocomposites

N. Beck-Tan'', S. Youngs and S. F Trevino''' '"^

Internally Oxidized Palladium Alloys: Particle Size Determination by

SANS

J. G. Barker'fs and T. B. Flanagan22i Investigation of the ZrgPt^^ Structure Type

J. K. Stalick'05 and R. Waterstrat'05

In Situ Neutron Reflectivity Measurements of Deuterium Absorption in Pd Films

B. J. Heuser'95, A. Munter'fs, N. Barber'^s, J. A. Dura'^^, and C. F Majkrzak'»5 Magnetic Cluster Sizes in Thin Film Magnetic Recording Disks

M. ToneyK, S. M. Choi'^'os, and C. J. Glinka'fs Magnetism in Layered Manganates

M. A. Green"" Measurement and Modeling of Residual Stresses in Multi-Pass Weldments

T. Gnaupel-Herold'»'»5, H. J. Prask'^s, R. Lloydse, and W. Reuters^ Microstructure of Alkali Activated Amorphous Binders

A, J. Allen'TM and J. Phair^" Microstructure Evolution of Fly Ash Blended Cements

A. J. Allen'°9 and R. A. Livingstones, and W. Bumrongiaroen^s

Morphological and Kinetic Study of Early Calcium-Silicate-Hydrate Gel Development During the Hydration of Cement and Tricalcium Silicate

H. M. Jennings'22, J. J, Thomas'22, and A. J. Allen'^ Negative Thermal Expansion in AOPO4 Compounds

A. W. Sleigtit'32 and T. Amos'32 Neutron Diffraction of Heusler Alloys

V.G.Harris"" and Q. Z. Huang'^'os Neutron Diffraction of Single-Wall Carbon Nanotubes

P Papanek2'0 '05, j. E. Fischer2'o, Z. Benes2'o, D. Colbert'is, and M. Heben'^ Neutron Diffraction Study of Copper(l)-Zirconium(IV) Chlorides

A. Dattelbaum'2i, J. Martin'21, and B. A. Reisner'^^ A New Double-Focusing Monochromator for "DARTS"

T. Gnaupel-Herold'«.'05, H, J. Prask'os, and M. Popovici2M Order-Disorder in CoFe/Carbon Composites

J. H. Scott"5, M. E. McHenry'9, Z. Turgut'^, and M. Storch'^ Phase Analysis of Sintered Yttria-Stabilized Zirconia

J. K. Stalick'»5, A. Slifka"2, and D. Balzar"2 Phase Composition Analysis of Plasma-Sprayed Partially Stabilized Zirconia Coatings by Neutron Powder Diffraction Data

H. Sitepu'" '^8.io5_ H. J. Prask'05, J. K. Stalick'*, R. Goswani'", and S. Sampath'"

Polymerized Fullerenes

S. F Trevino^ '"s, N. Beck-Tan^, and L. BaloghTM Pore Structure in Novel Ultra-Low Dielectric Constant Thin Films

S. Yang82 and E. K. Lin"5 Residual Stress Determination by Whole Pattern Analysis-Application

to Synchrotron HEXRD Measurements on Thermal Sprayed Coatings

T. Gnaupel-Herold'59 'os, D. R. Haeffner^ H. J. Prask'os, and J. Matejicek^ Residual Stress Determination for Welds in Navy-Ship Steel

T. Gnaupel-Herold'TM '05, H. J. Prask'os, and X. GtiengTM Residual Stresses in Thermally-Sprayed Coatings

J. Matejiceks", T. Gnaupel-Herold'^^ 'os, P C. Brand'°5, H. J. Prask'cs, H. Sitepu'^'^'os, and S. Sannpatti'S'

50 RESEARCH TITLES
Residual Stress in Thermally Sprayed Components for Automotive

Applications

J. Matejicek", D. Wilkosz«, T. Gnaupel-Herold"9 io=, H. J. Praski»5, H. Sitepui5?.i«.io5, and S. Sampath'S' Resolving Cationic Sittings in a new Dielectric Phase:

Bii sZnosTi, SKs^i

B. A. Reisner°5. and J. Chani»9 A Ring/Plug Reference Specimen for Residual Stress Measurements

T. Gnaupei-Herold'»i"5, C. S. Hehmans'.n^ N. Nguyen"' !", A. V. Clark'ss, and H. J. Praski»5 The Role of Water in Natural Disordered Opal-CT Samples

D. Bishso and G. Guthrie^o SANS Characterization of Hydrides in Uranium

S. Spooner2' , q Ludtkai2^ and J. G. Barkerios SANS Characterization of Low Dielectric Constant Polymer

Nanoporous Thin Films

W.-L. Wu'i5, E. K.Lin"5 B. Landes^^, and G. Barnes32 SANS of Hardened Cement Paste and Nanoporous Reference Materials

at Different Relative Humidifies

J. Adolphs'22 and J. J. Thomas^^^ SANS From Lithographically Patterned Polymer Thin Films

W.-L. Wu"5, E. K. Lin"^ N. R Berkios, and C. J. Glinka^* SANS Study of Anisotropic Microstructure in Plasma-Spray Coatings

H. Herman^s/^ A. Kulkarni"?, A. J. Alleni«, and G. G. Longifs SANS Study of Deuteride Formation and Decomposition in Palladium

B. J. Heuser^s and W. C. Chen^^ SANS Study of Fire Retardant Polymer-Clay Nanocomposites

H. J. M. Hanleyi2°, C. D. Muzny"", and J. Gilman'2' SANS Study of Nucleation of Aluminum Hydroxide

J. Watson^, R. Knotty and M. Y. Lin^? SANS and SAXS Determination of the Dispersion in Organic Solvents

of Organically Modified Clays for Polymer/Clay Nanocomposites

D. HoTM, R. M. Briber'* and C. J. Glinka^K SiOj Ultra Thin Films Round Robin

J. A. Duraio5, C. F. Majkrzakiis, and J, Ehrstein"6

Site Distributions in the Structure of BajSnjZnGa^o ^Cr.O^j (x = 3 and 4)

Q. Z. Huangi* R. Cava'*, I. S. Hagemanni"", X. P. A. Gao82, and A. R

Ramirez82 Size Distribution of Titania Particles in Coatings L-P Sungioe and D. Ho'»'»5 Small-Angle Magnetic Scattering From Nanocrystalline Cobalt

J. Weismuller"", R. D. ShulP""', R. McMichae|i°5, u. Erb'^, and J. G. Barkeri°5 Solute Effects on Membrane Thickness in DOPG and DOPC

J. Pencer'5'' and R, Hallett'^" Structural Distortions in the NaSrjMO^ (M = Ru,Rh) Family

B. A. ReisneriK, A. Prieto'TM, and A. Stacy"^ Structural Distortions in Titanites

B. A. Reisneri°5 and D, Xirouchakis''^ Structural Investigations of ETS-4 Microporous Molecular Sieves

M. Tsapatsis20', H. Hillhouse2w, R. Jacubinas^s, and B. Toby'"^ Structural Ordering in Erbium Doped Bi^Oj

B. A. Reisnerif'', E. Wachsman"i, T. J. Udovic'»5, and D. A. Neumann'os

Structural Refinement of Mixed-Metal Vanadium Phosphates

R DeSanto, Jr.'^o and D. Buttrey'* Structural Studies on High Dielectric Materials

R. Harlow- and M. Subramanian-*

Structural Study of Sr^Nb^Og Compound

I. LeviniM, j, Qhanios, and T. Vanderahi°9

Structural Studies of Strontium Niobium Oxides

W. Wong-Ngira, W. Greenwood"^ and B. H. Toby'os Structure of Barium Titanate Thin Films on Silicon

C. BouldiniM, B. Revehf^, and J. A. Borchers'°5 Structure, Cation Ordering and Magnetism in Manganate Spinels

M. A. Green'"' and D. A. Neumann'os Structure of CajAINbOg and CaTiOj Compounds

I. Levin'M, J. Chani»9, and T. Vanderah'^ Structure Determination of (Ca, Srj^iRhlrjDj by Powder Neutron

Diffraction

R. 0. Moyer"' and B. H. Toby"» Structure Determination of Framework Materials with the RHO

Topology

B. A. Reisner'05 Structure Determination of Lag^gSrg^zRuOj

Q. Z. Huang'M.ios, |. Natal i Sora'", A. 'Santoro'os, and R T. Vanderah'oa Structure of the Layered Cobalt Oxychlorides SrjCo^OjClj and

Sr^CoOjCI

Q. Z. Huang"9 '05, N. McGlothlin'"", T. He'"", and R. J. Cava"'o Structure of the n=2 and n=^ Member of the Ruddlesden-Popper

Series, Sr„,iSn„03„,, M. A. Green'"', K. Prassides2i6, p Day'"', and D. A. Neumann'^s

Structure and Oxygen Disorder in Sr^ gNd^ iCUjO,

Q. Z. Huang'« '05andW. Wong-Ng'09

Structure of Porous Manganese Oxides

M. A. Green'"', D. Arnold'"', and A. Lappas'"' Structure of Porous Silica Thin Films

W.-L. Wu^'5 and E. K. Lin''^ Structure Refinements of Alumo- and Gallo-Germanates Using Neutron

Scattering Techniques

S. Park'5', J. B. Parise'^', and B. H. Toby'os Structure Refinement of a Ferromagnetic Vanadium(lll) Sulfate

D. Groho|83, D. Hocm<i\ B. H. Toby'*, andQ. Z. Huangia'»5 Structure of 75.25:24.75 CaO-NbjOj

J. Chan'os, I. Levin'M, R. Roth'TM, T. Vanderah'TM, and B. A. Reisner'^s Structure of Sr, j^Dy, 125CU2O,

Q. Z. Huang'»'05 and W. Wong-Ngi«9

Structures of BagsSr^ ^CoOy Compounds

0. Z. Huang'59 '05 and R. J. Cava'"" Studies of Charge, Spin and Orbital Ordering in the System

Bii„Ca,Mn03

R Woodward'32, J. Goldbergeri32 and R N. Santoshi32 Synthesis, Structure and Electronic Properties of LaCa^Mn^O,

M. A. Green'"' and D.A. Neumann'^ Thermal Expansion of Alpha SIC From 15 to 298K

R. Reeber'2", K. Wang'21, and B. H. Toby'»5 Thermal Expansion of HgSe

R. Reeber'2i-'and K. Wang'2' Thermal Expansion of ll-VI Semiconductors

R. Reeber'2'. 'and k. Wang'2' Texture Characterization in X-ray and Neutron Powder Diffraction Data

Using the Generalized Spherical-Harmonic

H. Sitepui5'-'°5 i"8, H. J. Prask'»5, and M. D, Vaudin'o^ Texture Determination of (CFj)^ Films Using Neutron Diffraction

H. Sitepu'5"05."8^ T. Gnaupel-Herold'^'os, J. D. Barnes"5, and H. J. Prask'os Texture Determination of NAFION Using Neutron Diffraction

H. Sitepu'5'.i°5.i48, T. Gnaupel-Herold'ss 'os, S. R Trevinos- '"s, and H. J. Prask'is

NIST CENTER FOR NEUTRON RESEARCH 51
Texture in Plasma-Sprayed Coatings

H. Sitepu'".'05,i48^ T Gnaupel-Herold"9.io5_ s. Sampath's^ and H. J. Praski°5 Texture and Residual Stresses in Hydroformed Aluminum Tubing

T. Gnaupel-Herold"9.'05, H. J. Prask^os, and K. N. Shah3

POLYMERS

Aggregation of Fullerene-Based Star-lonomers

T.-L. Lin'TM, J. U-SerTM, and L. Wen Jiun'oo Behavior of Polymer Chains in Porous Media

M. P. Nieh"7, S. K. Kumar"', R. M. Briber'*, and L.-T, Ho'99.'°5 Chair Dimensions of Captured Micelle Star Polymers

L. Fetters^', M. Xenidou^', M. Y. Lin^'.'o^ and N. Balsara'S" Characterization of Dye Distribution in Polymer Thin Films

C. White"5, E. K. Lin"5, and W.-L. Wu"5

Characterization of Organically Modified Clays

L.-T. Ho'^'os, R. M. Briber'*, and C. J. Glinka'"^ Compatibility of Polyelastomers

D. Peiffer^?, M. Y. Lins? '*, and Y Zliang's?

Critical Neutron Reflection Tests of Polymer Interdiffusion Dynamics

R. P Wool'*', K. A. Welp'*, and W. Dozier'9" Dendrimer Like Vesicles

S. F. Trevino''^ '"s Dynamics of Polymer Interdiffusion

S. K. Satija'Ds

Effects of Clay on the Phase Behavior of Polystyrene/PVME Blends

R. Krishnamoorti'9^ K. Yurekli'^", and A. Karim"^

Effects of Substrate Interactions on the Ordering of Block Copolymer

Films

E. Huang2°', J. DeRouchey2°', and T. P Russel|2'"

Effects of Supercritical CO2 on the Phase Behavior of Block Copolymer

Melts

J. Watkins^"', M. Pollard2'", G. Brown20', S. Kumar'^', and T. P Russell-'"'

Electric Field-Induced Orientation of Diblock Copolymers in Thin Films

J. DeRouchey2"' and T. P Russel|2»'

Hybrid Nanostructures With Hydrophobically Modified Dendrimers

R Groehn"5and B.J. Bauer''^ Inelastic Neutron Scattering From Filled Elastomers

A. I. Nakatani"5, R. D. Ivkov'os, p Papanek2'° '°5, H. Yang'^", and M.

Gerspacher'^'" Interdiffusion of Cross Linked Polymer Films

U. Perez-Salas'S', R. M. Birber'^s, M. Rafailovich'^?, J. Sokolov's?, and N. F

Berk'05 Investigation of the Concentration Profile Between Cross Linked Thin Films

R. M. Briber'TM, U. A. Perez-Salas'?'', M. Rafailovich's?, and J. Sokolov'S'

In Situ Study of Molecular Conformation in Elastomeric Polypropylene in Uniaxial Extension

A. Gast'56 and J. Pople's^ Liquid Crystal Polymers in a Magnetic Field M. Dadmun2'8, W. Burghardt'2^ and N. Vaish" Low Energy Excitations in Deuterated Polystyrene

R. M. Dimeo'°5 and J. F Douglas''^ Melt Blended Polymer-Clay Nanocomposites

H. King3', A. Herhold^', and M. Y Lin^^ 'os Membrane Mediated Polymer Interdiffusion t H. Gruell"5, A. Esker"5, and C. C. Han"5. Microstructure and Properties of Hyperbranched Polymers

N. Wagner'* and Y KimS" Morphological Study of Comb Copolymer Pervaporation Membranes

A. Mayesti^, A. Akthakul^^, and Y-Y Won^s Multi-Dendrimer Nanostructures

F Groehn"5, E. Amis"5, and B. J. Bauer''^

Neutron Reflectivity From the Monolayers of SAN Random Copolymers

E. Kim53, H. KW\ K. Char'^s, and S. -H. Lee's^ 'os Neutron Studies of Polymer Dynamics in Intercalated Polymer-Clay

Nanocomposites

R. D. IvkoV's, P M.Gehring'os, n Maliszewskyi'^s, P Papanek^'" '"s, and R. Krishnapnoorti's" Order-Disorder Transition in Highly Asymmetric Block Copolymers

T. Lodge2°3, K. Hanley2°3, and X. Wang203

Phase Behavior of Confined Polymer Films

S. K. Kumar'3?, R. Jones'^', L.-T. Ho'»'05, and R. Briber'ss Phase Behavior of Multi-Component Polymer Systems in Compressible Solvents

J. Watkins20', G. Brown2')', V. RamachandraRao2(", B. VogP"', and T P

Russel|20'

Phase Behavior of Pentablock Copolymers

F. Bates2''3, T Lodge2»3, x. Wang203, Y Chen2»3, and C. Hardy^o^ Phase Separation in Polyolefin Blends

M. Modi''" and R. Krishnamoorli'"" Phase Transitions in Multicomponent Polymer Blends

N. Balsara'8^ and J. H. Lee'^ Polyethylene/Polymethylene Blends: Wetting and Phase Transitions Y Akpalu"5and A. Karinn''^ Polymer Brushes Under Shear

R. D. Ivkovcs, P D. Butler'fs '27, and S. K. Satija'os Polymer Interdiffusion Near the Polymer/Solid Interface

E. K. Lin"5, D. J. Pochan'M, W.-L. Wu"5, S. K. Satija'fs, and R. Kolb3? Polymer Liquid-Crystal Ordering at an Interface

G. Lynn2i8, E. K. Lin"5, W.-L. Wu"5, and M. Dadmun2i8 Polymer Supercritical Fluid Solutions

M. McHugh227, T diNoia", J. vanZanten", C. Kirby", T Kermis", and S. Conroy"

Polyolefin Polymer Blend Tie Chain Structures

D. Lohse37, R. Garner3^ and M. Xenidou3? Pressure Dependence of Phase Behavior in Styrene/N-alkyI

Methacrylate Block Copolymers

A. -V. Ruzette83, P Banerjeess, and A. Mayes^a Pressure Effects on the Aggregation of lonomers

D. Perahia25, T Hil|25 and X. Jiao25 SANS Investigations on a New Class of Nylon-6 Polymers

M. Kreitschmann''^ W. Pyckhoul-Hintzen''^ and D. Richter"" SANS Study of lonomer Blends

R. Tucker'89, R. Weiss'^^, and G. C. Han"5 SANS Study of Phase Separation in Model Polymer Networks

B. Viers'87 Shear Induced Polymer Desorption

E. K. Lin"5, R. Kolb"5, and W.-L. Wu"5

Shear-Induced Polymer Melt Desorption From an Attractive Solid Surface

E. K. Lin"5, D. J. Pochan'*, W.-L. Wu"5, S. K. Satija'*, and R. Kolb3' Small Angle Neutron Scattering of Water Dispersable Arborescent

Graft Copolymers

S. Yun'95, R. M. Briber'59, M. Gauthier225, and B. J. Bauer''^ Solution Properties of Dendrimer-Like Star Polymers

A. Gast'56 and J. Pople'^e Solvent Vapor Induced Swelling of a Polymer Brush

S. K. Satija'05, R. D. Ivkov'os, p D. Gallagher'os, and J. A. Dura'»5 Spinodal Decomposition in PS/PI Blends

H. Jinnai"\ M. Hayashi'^, and C. C. Han"5 Strain-Induced Interfacial Fracture Between Epoxy and Silicon Oxide

M. Kent'52 and W. F McNamara'52 Strained Polymer Networks

N. Gilra28, C. Cohen28, R. M. Briber'^', and T Panagiotopolis'99 The Structure of Associative Polymers at Rest and Under Shear

X. Meng'"", I. Goldmints'"", and W. Russel'""

52 RESEARCH TITLES
structure of Filled Elastomer Thin Films

Y. Zuangi57, B. Tani^?, M. Rafailovich's?, J. Sokolovi", and M. Y. Lina' ^os

Structure of Fluorosilicone Networks

F. Horkay* and E. Geissier"2 Structure of Nation in Various Solvents

S. F. Trevino^ S. Younge, and N. Beck-Tan^ Surface Segregation in Binary Blends of Topologically Distinct Polymers

M. D. Foster's, C. C. Greenberg^'e, and D. M. Teale'^^ Structure and Aggregation Kinetics of Asphaltenes

T. Mason37, M. Y Lin^'^i"^ and E. Sirota^' Structure of Adsorbed Polyelectrolyte Multilayer Thin Films

C. Barrett83 and A. M. Mayes^^ Structure and Morphology of Semicrystalline Polymer Thin Films

D. J. Pochan^*, E. K. Lin"^, W.-L. Wu"^, S. K. Satija'^s, Q. F Majkrzaki°5, and R. Kolb^- Study of Thermodynamics in Star and Linear Polymers

M. Foster"6 and T. Zook"*^ Thermal Expansion and Glass Transition Behavior of Polymer Films:

Effect of the Free Surface and Confinement Between Non-Interacting Surfaces

D. J. PochaniM, E. K. Lin'^s, W.-L. Wu"5, S. K. Satijai^, and S. Z. D. Cheng^^

Thermal Expansion and Glass Transition of Thin Polymer Films Sandwiched Between Polymer Layers

D. J. Pochan"», E. K. lm^'\ and W.-L. Wu"5

COMPLEX FLUIDS

Effects of Alcohols and Salts on the Structure of Gil-in-Water Microemulsions

J. Lettowa3, J. Yingea. and C. J. GlinkaiQ^

Effect of Shear Combined with a Proximate Surface on Surfactant Sponge Phases and the Sponge to Lamellar Transition

W. A. Hamilton'2', P D. Butler»5 '2', G. Warr^^', and L. Porcar^' Electrostatic and Counterion-Specific Effects on Micelle Morphology

Probed with SANS

L. J. Magid2i3, P D. Buller'05.i27_ z. Hans's, and X. Xu^^a

Field Driven Phase Transitions in Monolayers and Bilayers of Amphiphiles at Electrode Surfaces

J. Lipkowski^'^', J. Majewski8», and G. Smith^" Interactions of Charged Polymerized Rod-Like Micelles With

Oppositely Charged Surfaces

S. M. Choi"9 and S. R. Kline'cs Influence of Counterion Valence on Domain Size of Polyelectrolyte Solution Y Zhang"5 and E. Amis^is Magnetic Alignment of Discotic Liquid Crystals

B, Patens and S. M. Ghoi^'os Microemulsion Structure at an Interface

G. Warr2", J. Schulz2i', P D. Butler'* "7, and W. A. Hamilton'^' Microstructure of Alkylpolyglucoside Micelles and Microemulsions

L. D. Ryani5o, D. lanspetro'^", C. McKelvey"", J. Silas'*, and E. W. Kaler's" Octane Wetting of an Air/Water Interface

S. Satija'»5 and R. D. lvkov'»5 Phase Transitions in Ferrofluids

W.-L. Lou"', M. Y Lin37 '«, q q. Dender'os, and J. W. Lynn'»5 Poiseuille-Flow-lnduced Changes in the Structure of Surfactant Micelles

L. Walker's, b. Poore'^, M. Truong'^, and Y Christanti's Polymer, Block Copolymer and Clay Solutions Under Shear

G. Schmidt"5, C. C. Han"5, and P D. Butler'os 'z?

Polymerization of Rod-Like Micelles

S. Svenson'*, R. Prud'homme'"", and P Peiffer^'

Pressure-Induced Swelling of Polymer Micelles in Supercritical Fluids M. McHugh22', T. dlNoia^', J. vanZanten", C. Kirby", T. Kermis", and S. Conroy"

SANS Determination of the Persistence Length in Rod-Like Micelles

L. J. Magid2'8, P D. Butler'os '2?, and Z. U2'8 SANS Determination of the Structure of Vitrified Microemulsions

G. Warr2'6, PR. Harrowel|2'^ A, Widmer-Cooper2", and P D. Butler'05.127 SANS From Nanodroplet Aerosols

B. Wyslouzi|23i, C. Heath23', K Streletzky23', G. Wilemski2»5, and R. Strey'TM SANS and Reflectivity Studies of Complex Polymer Mixtures

R. Briber'99, B. J. Bauer''^, and M. Gauthier225 Solution Structure of Novel Polymerizable Surfactants

S. R. Kline'05 Structure and Aggregation Behavior of Aqueous Solutions of Fulvic Acid

M. Diallo'sandC. J. Glinka'os Structure and Aggregation of Soot in Flowing Motor Oil M. Y Lin3', M. Francisco^?, and E. Sirota^' Structure of Dendritic Diblock Copolymer Langmuir Films

P Hammond83 and J. lyer^a Structure of Wax in Solution

E. Sirota37 and M. Y Lin3?.'05 Vesicle and Micelle Formation of Block Polypeptides

D.J. Pochan'90 andT. Deming'S"

CONDENSED MATTER PHYSICS

Anomaly in the Magnetic Phase Diagram of U^.J^Pd^Alj

T. M. Kelley'8', W. P Beyermann'S', R. A. RobinsonTM, J. W. Lynn'fs, E. J. Freeman'82, E, D. Bauer'82, and M. B. Maple'f^ Antiferromagnetic Ordering of Composite Spin Degrees of Freedom in La4Cu3MoOi2

M. Azuma'^ C. Broholm" '05, and Y Qiu"

Antiferromagnetic Structure Determination: Exchange-Based MnPdBased Thin Films

J. A. Borchers'05, R. F Farrow*, and M. Toney^s Antiferromagnetic Structure Determination in NiO Nanoparticles

R. Kodama"" and J. A. Borchers'»5 Asymmetric Magnetization Reversal in Positive Exchange Bias Hysteresis Loops

M. Fitzsimmonsso, A. HoffmanTM, I. K. Schuler'82, and C. Leighton'82 Charge, Orbital Magnetic Ordering and Two-Phase Coexistence in Lai,2Cai/2Mn03

Q. Z. Huang'99''o^ J. W. Lynn'os, V. Smolyaninova'^s, K. Gfiosh's^, R. L. Greene'*, D. C. Dender'»5, R. W. Erwin'*, and A. Santoro'os

Critical Exponent in Equilibrium Fe g^Zn^gF^ Thin Film Random Field System

D. Belanger'85, R. Erwin'^s, D. Lederman23" Crystal and Magnetic Structures of FeOCI

W.-H. Liw, S. Y Wu'", 0. G. Wu9", and J. W. Lynn'o^

Crystal and Magnetic Structures of LajRuO^, LayRUgO^e and La^Ru^O^z

Q. Z. Huang'59 '05, R. Cava'"", R. W. Erwin'*, and J. W. Lynn'*

Crystal and Magnetic Structures of PrBa^Cu^jOg

W.-H, Li^^ S. Y Wu^", and J. W Lynn'os

Crystal and Magnetic Structures of SrjRu^Oy and Sr4Ru30^o

R. L. Harlow33, M. K. Crawford33, J. W. Lynn'*, Q. Z. Huang'^'*, S. Skanthakumar", and G. Cao"' Crystal and Magnetic Structures of Sr^Fe^COg

Q. Z. Huang'99.'*, R. Cava""', R. W. Erwin'*, and J. W. Lynn'*

Crystal and Magnetic Structures of TbBaCo^Oe

Q. Z. Huang'* '*, I. Troyanchuk'2, and J. W. Lynn'*

Crystal and Magnetic Structures of ZnCr^ 4Gaoe04

S.-H. Lee'»'*, W. Ratcliffe'so, T. H. Kim'TM, and S.-W. Cfieong'TM 82

Crystal Structure and Magnetic Ordering in C0M0O3

Q. Z. Huang'* '*, J. W. Lynn'*, R. W. Erwin'*, and M. Crawford33

NiST CENTER FOR NEUTRON RESEARCH 53
Crystal Structure and Magnetic Ordering in tlie Perovsl(ite SrRUo33lVlnoj,03

Q. Z. Huang'»i»5 and R.J, Cava'"" Crystal Structure and Magnetic Properties of TbjfFe^ .CoJ^^ Ji^ ^ Alloy

V. G. HarrisTM and Q, Z. Huang'99 '»5

Crystallographic and Magnetic Structure of a Series of Lanthanide

Copper Oxides: LnCu204

B. A. Reisneri"5 '5', A. Stacy'TM, and J. Luce'TM Crystallographic and Magnetic Structure of Tb2Ni3Sis

F. BourdaroP'''"5, J. W. Lynn'os, and L. Guptaie" Crystallographic Study of Lage^MgjjMnOj

C. R Adams'w '05, J. W. Lynn'*, R, G. Williams'^s, and G, M. Zhao's^ Density of States in Isotope Substituted La5/3Ca3,8Mn03

C. A, Adams'^'os, J. W. Lynn'°5, S-W. Cheongi5".82, w. Ratcliffe'S", and

L. Young's" Determination of the Dimensionality of the Gapped Spin-1/2 System

in CuHpCI

M. Stone", D. H. Reich", and C. Brotiolm""'5 Diffuse Scattering From Nano-Polar Regions in Relaxor Ferroelectric Ki.,LiJa03

G. YongTM, R. W. Erwin'fs, and J. ToulouseTM Dynamics of the Relaxor PMN

R M. Gehring'»5, G. Stiirane's, and S. B. Vaktirustiev^a

Effect of Superconductivity on the Lattice Dynamics of BaQsKg^BiOj Y S. Lee'cs, C. R Adams'^ J, W. Lynn'^^, and S. N. Barilo'^

'

Effects of H on Magnetic Coupling in FeV Superlattices

B. Horvarsson'^, G. Andersson'^e, J. A. Dura'»5, T. Udovic'os, and C. R

Majl<rzal<'» Field Dependence of Magnetic Ordering in a System of Weakly

Coupled Antilerromagnetic Spin-1/2 Y Chen", D. H. Reich", and C. Broholm" '*

Field Induced Magnetic Order in the Antiferromagnetic Spin-1 Chain

NDMAP

Y Chen", Z. Hondas^, A. Zheludev'^, C. Broholm" '»5, K. Katsumataf'^, and S. M. Shapiro'5 Field Induced Magnetic Order in Spin Ice DyJi^O^ Y Qiu", L Hagemann'^o, R. J. Cava'"", and C. Broholm" '"^

Field Induced Ordering in Spin Ice DyJi^O,

L Hagemann'*, R. J. Cava'"", C. Broholm" '°5, and Y Qiu"

Field and Temperature Dependent Neutron Scattering Study of Mn^j

Magnetic Molecules

T. Yildirim'* and S.-H. Lee'* '"^

First-Principles Investigation of Structural and Electronic Properties of Solid Cubane and Its Derivatives

T. Yildirirn'os, S. Ciraci'", and C. Kilic'" Flux Lattice Structure in Nb and BaKBi03

X. Ling", D. C. Dender'05.199, J. W. Lynn'*, S. M. Choi'* '"s, and S. Rark'? Gap in the Excitation Spectrum of the Frustrated Two Dimensional

Spin-1/2 Magnet PHCC

IVI. Stone", D. H. Reich", C. Broholm" '*, and I. Zaiiznyak's Ground-State Selection in FCC and BCT Antiferromagnets Due to Quantum Disorder

T. Yildirim'°5, A. B. Harris2'°, and E. R Shender'TM Incommensurate and Commensurate Magnetic Structures in the Magnetoresistive R2Ni3Sig Materials F Bourdarot2'"'5, S. Skanthakumar^ J. W. Lynn'fs, and L. C. Gupta'^o Incommensurate Magnetic Structure of CeRhln^

W. Bao"", R G. Ragliuso'"5, J. L. SarraoTM, J. D. Thompson'*, Z. Fish'*, J. W.

Lynn'*, and R. W. Erwin'* Incommensurate Spin Fluctuations and Structural Transitions in Excess Oxygen-Doped La^CuO^^, Y S. Lee'*, R. J. Birgeneau^s, B. Khaykovichss, M. A. Kastner83, and R. W.

Erwin'* Influence of Interface Structure on the Magnetic Polarizability of a Pd-Co Alloy Overlayer in Close Proximity to CoPt3

M. Fitzsimmons'i", F Hellman'82, B. IVIaran's?, and A. Shapiro'82

Interfacial Magnetic Structure in Spin-Dependent Tunnel Junctions

K. V. O'Donovan'*, J. A. Borchers'*, and S. S. Rarkin^^ Interlayer Spin Coupling in FeMn-Based Spin Valves

J. A. Borchers'*, C. F Majkrzak'*, A. Reilly26, W. R Rratt, Jr.», J. Bass^o, and D. C. Dender'* Long-Range Magnetic Order in Hybrid Co/Cu Multilayers

J. A. Borchers'*, W. Rratt^o, and J. Bass^" Local Spin Resonance in a Frustrated Antiferromagnetic ZnCr204

S,-H, Lee'*'*, C. Broholm" '*, T H. Kim'^o, w. Ratcliff'TM, and S-W.

Cheong'5».82

Lovi/ Energy Magnetic Correlations in the Quantum Critical Spin

System CeNijOe^

A. Schroeder", D. McMorrow'''^ N. Beck-Christensen'"'', C. Broholm" '*, Y

Qiu", and G. Aeppli'03 Magnetic Correlations in Discontinuous Co-SiO^ Thin Films and

Multilayers

S. Sankar'99, A. E. Berkowitz'82, D. C. Dender'* 'TM, J. A. Borchers'^s, R. W.

Erwin'*, S. R. Kline'*, J. A. Dura'*, and C. R Majkrzak'*

Magnetic Correlations and Lattice Distortions in the Bilayer Manganite

La^ 2Sr, 8lVln207

L. Vasiliu-Doloc'23, S. Rosenbranz^ R. Osborn", S. K. Sinha", J. W. Lynn'*, and J. F Mitchell" Magnetic Correlations in Li-Doped La2Cu04

W. Bao8' and S.-H. Lee'^^.i* Magnetic Correlations in a Geometrically Frustrated Magnet ZnV^O^

S.-H. Lee'»io5, c. Broholm" '*, and Y Ueda'^f Magnetic Correlations in the Heavy Fermion System LiV^O^

S.-H. Lee'99'*, C. Broholm" '*, and Y Ueda'^^ Magnetic Correlations in a System of Coupled Spin-1/2 Dimers CuHPCI

M. Stone", Y Chen", D. Reich", and C. Broholm" '* Magnetic and Crystal Structure Phase Transitions in R^fiaJCoO^ (R = Nd,Gd)

I. 0. Troyanchuk'2, D. D. Khalyavin'2, T K. Solovykh'2, H. Szymczak'2, Q. Z. Huang'»'*, andJ. W. Lynn'*

Magnetic and Crystal Structures of CaRu03

J. W. Lynn'* and I. Felner'« Magnetic and Crystal Structures of the New Heavy Fermion Compound

CeRhSn

E. Granado'82, J. W. Lynn'*, E. D. Bauer'82, A. Zapf'82, and M. B. Maple'82 Magnetic Domain Structure of Thermally Treated Nanocrystalline

Ni3Fe

H. Frase'8 and L. Robertsoni2? Magnetic Excitations in Alternating ID Magnetic Chains

A. B. Harris2'oandT Yildirim'* Magnetic Excitations in Mn-12 and Fe-8 Magnetic Clusters T Yildirim'*and S. H. Lee'w*

Magnetic Order and Crystal Field Effects in RNiBC

F Bourdarot2' '*, J. W. Lynn'*, Q. Z. Huang'» '*, D. R. Sanchez22, M. B. Fontes22, J. C. Trochez22, and E. Baggio-Saitovitch22 Magnetic Order in EuMn^P

J. Y Chan'*, J. W. Lynn'*, S. M. Kauzlarich'", A. Rayne''^, and B. A. Reisner'* Magnetic Order in the Ferromagnetic Superconductors RuSr^^^oGdCu^Og

J. W. Lynn'* 8. Keimer^" '"o, C. Ulich'"", C. Bernhard'"", and J. L. Tallonss Magnetic Order in Pr-Containing Cuprate Superconductors

W.-H. LIS", K. C. Lee«", H. C. Ku'"", and J. W. Lynn'* Magnetic Order, Structure and Spin Dynamics of (La^ .CaJMnOj

, J. W. Lynn'*, R. W. Erwin'*, J. A. Borchers'*, Q. Z. Huang'» '*, A. Santoro'*,

K. Ghosh'99, and R. L. Greene'* Magnetic Order in the Superconductor RNi^B^C

J. W. Lynn'*, S. Skanthakumar", Z. Hossain'TM, L. C. Gupta'^", R. Nagarajan'eo, and C. Godart2' Magnetic Ordering in Co^SnO^

M. K. Crawford33, R. B. Flippen^s, R. L. Harlow33, J. Hormadaly^a, J. W. Lynn'*, andQ. Z. Huang's^ '*

54 RESEARCH TITLES
Magnetic Ordering of Exchange-Biased FejO^NiO Superlattices

J. A. Borchers'K, R. W. Erwinifs, Y. D. M. Y. Lind"', P. G. Ivanov" A. Qasba'°5, K. V. 0'Donovani» Magnetic Ordering in the Frustrated Heavy Fermion System UNi^B

J. MydoshTM, C. Broholm'i ios, and Y Qiu"

Magnetic Ordering of Mn in Nd^ .Ca.MnOj

S. Y. Wus-*, W-H, Lis", K. C. Lee«, J. W. Lynn'"5, R. S. Liu's, J. B. and

C. Y Huangios Magnetic Ordering and Structure of PrBa^FOjOg

N. Rosov'05, J. w. Lynn'os, M. Seyedahmadian82, and T. Yeun^z Magnetic Properties of H0VO4

C. K. Loongi, S. Skanthakumar^ J. W. Lynnifs, and G. K. Liu^sa Magnetic Proximity Effect in Pd

A. HoffmannTM and M. Fitzsimmonss" Magnetic Structure of Charge Ordered CaFeOj

E. Moshopoulouis, D. E. Cox", and R Woodward^^^ Magnetic Structure and Interlayer Correlations in Ferromagnetic

Superlattices EuS/Pbs

H. Kepa223 and T. T. Giebultowicz"2 The Magnetic Structure of [MnTPP][TCNE] 2PhMe by High-Resolution Neutron Powder Diffraction

C. R. Kmety-Stevensoni29, A. J. Epstein'^s, J. S. Miller22", E. J. Brandon22o, and J. W. Lynn^fs Magnetism of Ferrihydrite Nanoparticles

M. S. Seefira23", V. Suresfi Babu^^o, and J. W. Lynnios Magnetization of Antiferromagnetically Ordered UCu^ ,Pd,

T. M. Kelleyi3i, W. R Beyermann'si, R. A. Robinsonso, J. W. Lynn'fs, E. J. Freeman'82, e. D. Baueri32, R. Cfiaui82, and M. B. Maplei82 Neutron Coherence Length and Non-Specular Scattering From

Diffraction Gratings

C. R Majkrzaki* and N. R Berk'os Neutron Scattering Study of the Nuclear and Magnetic Structure of RD3

T. J. Udovic'05, Q. Z. Huangi99 J. W. Lynnios, R. W. Erwini°5, and J. J. Rusfi'K Neutron Studies of New Incommensurate Magnetic Correlations Near

the Lower Critical Concentration for Stripe Order in La^ e ,,Ndo4Sr,Cu04

J. M. Tranquada'5, N, ichikawa'69, R M. Gehringi°5, and S.-H.' Lee'9M05 Observation of a Magnetic Spiral in an Exchange-Spring Magnet

K. V. O'Donovanifs, J. A. Borcfiers'^s, and E. E. Fullertonios Oxygen Isotope Effect on the Spin and Lattice Dynamics of La^^ Caj/sMnOj

C. R Adams'»'«^ Y S. Leei»5, J. w. Lynn'fs, V. Smolyaninova"9, G. M. Zhao^^g,

R. L. Greene"9, S.-W. Cheong'M.82 and W. Ratcliffe'so Polarized Neutron Diffraction Studies of Magnetic Ordering in Exchange-Biased Fe304/Co0 Superlattices Y Ijirii28, J. A. Borchersio5, R. w. Erwini*, s.-H. lee'^^">\ G. R Maikrzaki"5, R

J. van der Zaag^sf, and R. M. Wolf"8 Polarized Neutron Reflectivity of an Array of Cobalt Dots

S. Adenwalla2°' and C. R Majkrzak'°5 Polarized Neutron Scattering Measurements of the Oxygen Moment in (La.SrjMnOj

R M. Gehringio5, G. Shirane^s, H. Hirota'^s, and J. W. Lynn'fs Polarized Neutron Studies of Magnetic Interfacial Roughness in EuTe/ PbTe Superlattices

H. Kepa223, T. Giebultowicz"2, G. Baueri32, and C. R Majkrzaki»5 Pr Magnetic Order and Spin Dynamics in the Cuprates

J, W. Lynn"5, N. Rosov^o^ S. N. Bariloi2, L. Kurnevitchi^, and A. Zhokfiov'« Pressure Dependence of the Magnetic Order in UGe^

J. W. Lynn'K, E. J. Freemanis^, and M, B. Maplei82 Q-Dependence of the Spin Flip Scattering From Exchange Coupling

Across Fe-FeFj Interfaces Measured With Spin Polarized Neutron

Diffraction With Polarization Analysis

M. Fitzsimmons^o and 1. K, Scfiuler82, c. L. Leighton'82, and A. Hoffmans" Quantum Percolation on the Square Lattice: Crystal Growth, Neutron

Scattering and Monte Carlo

0. R Vajk'55, M. Greven'56, R K, Mang'^e, and J, W. Lynn^s

Reflectivity Measurements on Spin Valve Structures

D. Sarkisov2i'' and M. Dabaghian2ii Search for Spin Density Waves in Pb

A. Overhauser"" and J. W. Lynnios Self-Assembled Polymer-Like Structures and Effect of Fields in PhaseSeparated Magnetic Fluids M. Y Lina'.ifs, T. Du'"', J. W. lym^°\ and W. Luo"" Single-Ion Anisotropy and Crystal Field Effects in R^CuO^ (R = Nd,

Sm, Pr, ...)

T. Yildirimio5, R. Sachidanandami^^, a. Aharonyies, and A. B. Harris2H' Spin Correlations in (Nd-Ce)2Cu04 R K. Mang'56, M. Greven^e, and J. W. Lynn^os Spin Dynamics of CrOj

E. Granado"9 i»^

J. W. Lynni°5, and M. Rubinstein"" Spin Dynamics of the Mn Ions in La^ .Ba.MnOj and Pr^ .Ba.MnOj

J. W. Lynn'°5, L. Vasiliu-Doloc'23, K. Ghoshi«, R. L. Greene"9, and S. Barilo'2 Spin Dynamics in LaTiOj

B. Keimers"!"", A. Ivanovs^, J. W. Lynn"», Y Taguchii^, and Y Tokurai^a Spin Dynamics and Change Ordering in Single Crystal La7Ca3Mn03

C. R Adams"9. 105^ j w. Lynn"», and Y M. Mukovskii92 Spin Dynamics of Strongly Doped La,„Sr.Mn03

L. Vasiliu-Doloci23, J. W. Lynn'fs, Y M, Mukovskii92, A. A, Arsenov92, and D.

A. Sfiulyatev92 Spin Order and Dynamics in Bi^Sr^CoOg^^ Y S, Lee"i^ J. W. Lynn'°5, R C. Chou83, M. A, Kastner", T. Imai83, and J. K. Thomases

Static and Dynamic Properties of Spin and Charge Ordering in La^ xSr.Ni04

S.-H. Leei99.'05, J. M. Tranquada^, and K. Yamada'f* Structural Phase Transition and Magnetic Order in Heavy Fermion

Compounds CCjM with M = Al, In and Sn

W.-H. Li9^ K. C. Lee9^ Y Y Chen82, and J. W. Lynn^* Structure and Frustrated Magnetism in KFe3(0DyS04)2 Y S. Lee^fs.igg^ j w. Lynn^o^ Q. Z. Huang^s.^os^ b. Toby^os, S.-H. lee^os.m^ q

Groho|83, and D. Nocera83 Structure and Magnetic Order in the A3BO4 Spinel (A = (Co, Ru), B = (Zn, Ga, Ge))

Q. Z. Huang'9a'05^ j w. Lynn'os, R. w. Erwini»5, M. Grawford^s, R. L. Hariow33, and E. M. McGarron33 Structure and Magnetic Order in Sr^Yg gCa,, ^Co^Og

Q. Z. Huang'99.'05, j. w. Lynnifs, R. w. Erwin^os, and R. J. Cavai^" Structure and Magnetic Ordering of Mi'[N(CNy; (M = Co, Ni, Mn)

J. L. Manson^ C. R. Kmety-Stevenson'^s, Q. z. Huang"9.io5, j. w. Lynn^s,

G. Bendele"', S. Ragola'", R W. Stepfiens"?, L. M. Kiable-Sands", A. L. Rheingoldi5, A. J. Epsteini29, and J. S. Miller22o Structure and Magnetic Properties in the Sr^ .(LaggNa,, gj.RuOj Solid Solution

0. Z. Huang'99.105 and R.J. Cava""

Structure of YCOg ^MOg 5O3 „, Tbg gBag 5C0O, and Ndg ^Bag jCoO,

Q. Z. Huangiw J. W. Lynn^os R. W. Erwinios, and I. Troyanchuki2 Structure of PZN-PT Under Electric Field R M. Gehring'M, q. Sfiirane", K. Hirota'TM, S.-E. Park"?, and T. R. Shnut"? Structures of YM^CUj asReg igO^^JM = Ba and Sr) High T, Superconductors

Q. Z. Huangi99,'05 m. Marezioee, R Licci«, and A. Santoro"i5 Study of Metallic Stripes and Charge Order in Superconducting

Lai6.,Ndg4Sr,Cu04

N. Ichikawa'69, S. Uchidaiea, J. M. Tranquadai=, T. Niemolier52, P M. Gehringi"5, S.-H. Leeio;^ "9^ and J. R.Schneider52 Superconductivity in La2„Sr,Cu04

S. Wakimoto^TM^ s. Ueki'TM, k. Hirota«8, K. Yamada'^s, Y Endoh'^s, R. J. Birgeneau83, Y S. lee«\ M. A. Kastner83, G. Shirane^s, S.-H. Lee'»5.i99, and R

M. Gehring'K

NiST CENTER FOR NEUTRON RESEARCH 55
Superconductivity, IVIagnetic Fluctuations and IVIagnetlc Order in TbSr2Cu2 6g IVIo„3,07 W.-H. Li'", W. Y. Chuangss Y. Wu^", K. C. Lee9^ J. W. Lynnios, H. L. Tsay^^, and H. D. Yang's Surface Spin Ordering in LaFeOj Thin Films

J. A. Borchersi"5, J. Stohrss, and M. Toney^s Synthesis, Crystal Structure and Magnetic Order of the Ion Oxycarbonate Sr4Fe2C0e

K. Yamaura^"", Q. Z. Huang'^ i^s, j. w. Lynn^"^ R. W. Erwin'o^, and R. J. Cava'"" Temperature Evolution of the Spin Excitation Spectrum in a Reentrant

Spin Glass FegyAlgj

W. Bao8», S. Shapiro'5, and S.-H. Lee^wo^ Two-Step Short Range IVIagnetic Order in the Spinel LilVln204 W.-H. Li«, C. C. Yang9^ H. Y Wangw, S. R. Hwang^, K. C. Lee^, J. W. Lynn'os,

R. S. Liu5^ and C. H. Client Variation in the Structural and IVIagnetic Properties Induced by La Doping in Pr(Ba^ .LaJ^CUjO;

H. Y Wang"", C. H. Chang9^ S. R. Hwang^"", W.-H. K, C. Lee9^ J. W.

Lynnios, H. M. Luo'", and H. C. Ku'TM Vortex Lattice and IVIagnetic Order in ErNi^BrC R Gamme|i53, S. Lopez"3, D. C. Dender«, S. M. Choi'»i«, and J. W. Lynn'os Vortex Lattice Structure in High-T, Bi-2212

B. Keimer''o.84^ j. Fong'«', and J. W. Lynn'^s X-ray Dichroism/Neutron Reflectivity Analysis of In-Plane Ferromagnetic Domains in Co/Cu Y Idzerda"', J. Bass*, W. PrattTM, J. A. Borchers'os, and K. V. 0'Donovani°5

BIOMOLECULAR SCIENCE

Amplitudes of Protein Motion: Resolution of a Discrepancy Between

Neutron Scattering Experiments and MD Simulations

M. Tarek2ot)'i»^ G. L. Martyna^s, and D. J. Tobias'so Characterization of Polymeric Membrane Mimetic Films Using Neutron

Reflectivity

S. Kruegerios, C. R Majkrzakins, C. W. Meuse"", and E. ChaikoP^ Cryopreservation of Proteins

A. M. Tsai'°5, C. L. Soles"^ and J. Shiloach* Determination of the Location of the Lipid Anchor in Outer Surface

Protein A of Borrelia Burgdorfei by SANS

D. Sctineider'5, C. Lawson^s, and V. Graziano'^ The Dynamics of Fibrinogen and Related Fibrin Gels

R. Nossal*, A. M. Tsai'fs, and D. Sackett* The Dynamics of Protein Hydration Water: A Ouantitative Comparison

of MD Simulations and Neutron Scattering Experiments

M. TarekTM '°5 and D. J. Tobias^TM Environmental Dependence of the Dynamics of Protein Hydration Water

M. Tarek2oo '"5and D. J. Tobias's" Gelation of Methylcellulose

C. -l. Huang203 and T. lodqe^os Incoherent Scattering From Lipid Bilayers and Bilayers With Channel

Proteins Imbedded

S.-H. Ctien83, C. Liao^, T. Weiss'« and C. M. Brown"'', los

Interaction of the Peptide Penetration with Phospholipid Double

Bilayers

G. FragnetoM, E. Bellet-Amalric«, R Graner^s, and L. Perinos^

Interfacial Morphologies of Phospholipid Membrane Systems

B. Gaulin86, R Mason23, and R. Epand^^ Internal Organization of Peptide-Nucleic Acid Complexes Derived From SANS

R Schwarz2° and S. Krueger^s Interpretation of Specular and Off-Specular Reflectivity Data From

Patterned Thiahexaethyleneoxide Alkane Surfaces

N. R Berk'«5, Q. R Majkrzakifs, A. Munter'^s, J, Woodward"^', C.W. Meuse"",

A. L. Riant'"', and S. Krueger'^s

In Situ Measurements of Melittin Insertion Into Hybrid Bilayer

Membranes

S. Krueger'cs, C. R Majkrzak'fs, J. A. Dura'fs, A. L. Rlant'o^ and C. W. Meuse"" Magnetic Field Alignment of Mixed Lipid Discotic Micelles

J. Katsaras23, R. Prosser'^ S. Krueger'os, and C. J. Giinka'°5 Membrane Active Peptides: Phase Transitions and Supramolecular

Assemblies of Peptides in Membranes

H. W. Huang'^, W. Heller'*, T. Harroun'«, and L. Yang'^ Molecular Dynamics of Solid-State Lysozyme as Affected by Glycerol and Water

A. M. Tsai'°5, D. A. Neumann'os, and L. N. Belps Motion in Alpha-Lactalbumin and Alpha-Lactalbumin Molten Globule

Studied by Ouasielastic Neutron Scattering

Z. Bu"5, D. A. Neumann'05, and C. C. Han"5 Neutron Diffraction Studies of Peptides in Fluid Lipid Bilayers

S. Wtiite'8" and K. Hristova'TM Neutron Reflectivity Studies of Protein Adsorption/Desorption on the Surfaces of Self-Assembled Monolayers

M. D. Foster"^^ S. Petrash^e, and C. R Majkrzak'os Ordering in Protein/Polelectrolyte Multilayers

J. RuslingTMand Y Lvov'"' Phase Behavior of Magnetically Alignable, Mixed Lipid 'Bicelles' M.-R Niehi37, J. Katsaras23, C. J. Glinka'"5, S. Krueger'"5, and R. S. Prosses'" Potential of Mean Force Between Neurofilaments at Different Concentrations

S. Krueger'os, M. Paulaits", J. Hoh", and S. Kumar'3' Protein Adsorption at Solid/Liquid Interfaces

J. R, Lu2'5, T. J. Su2i5, and B. Green2i5 Ouasielastic Neutron Scattering Study of the Dynamics of Water in Saccharide Solutions

A. M. Tsai'"5, M. Feeney'"", R G. Debenedetti'"", and D. A. Neumann'cs Rnase-A Dynamics by Time-of-Flight Neutron Scattering: A Case Study

in Protein Dynamics and its Implications for Drug Design, Formulation and Delivery

A. M. Tsai'"5, T. J. Udovic'"^, J. R. D. Copley'"5, D. A. Neumann'*, J. J. Rush'"5, M. Tarek2""^ '"5, D. Tobias'^", and G. Giililand'"' SANS Study of Catechol Dioxygenases From Pseudomonas Putida SH1

S.-L Huang"^ W.-H. and J. W. Lynn'"^ SANS Study of Colloidal Interactions of Proteins

0. Velev'50, P Hinderliter'?", J. Silas'*, and E. W. Kaler'"" SANS Study of Cyclic-AMP-Dependent Protein Kinase

J. ZhaoTM, J. Trewhella8", D. Walsh"", and R. Bruschia'^' SANS Study of the DNA/Flap Endonuclease Complex

J. TrewhellaTM, C, Kimso, and S. Gallaghers" SANS Study of the FerrodoxinTOL Component of Toluence Dioxygenase From Pseudomonas Putida F1

S.-L. Huang"^ D. T. Gibson'"', W.-H. Li"^ and J. W. Lynn'"^ Solution Structure of Cyclic AMP Receptor Protein/DNA Complexes

R Schwarz2" S. K. Gregurick2"", and S. Krueger'"5 Structural Investigation of the High Temperature Protonic Conductors

C. Karmonik2''3, Q. Z. Huang'"". '"s, T. J. Udovic'"", and J. J. Rush'"^ Structure of Hybrid Bilayer Membranes by Direct Inversion of Neutron

Reflectivity Data

C. Maikrzak'"5, N. R Berk'"5, C.W. Meuse'"', V. Silin'"', A. L. Plant'"', and S. Krueger'"5 Structure of Intact Influenza Hemagglutinin Protein Containing the

Viral Membrane Spanning Region

R. Blumenthal"", D. Remeta'*, S. Durell"", and S. Krueger'"^ Structure of Microtubule-Based Cellular Motors Investigated by SANS

R. Mendelson'83, D. Stone'"", and R. Hjelm"" Temperature Effect on the Structure and Activity of Catechol 2.3-Dioxygenase From Pseudomonas putida SH1: A Small Angle

Neutron Scattering Study

S. L. Huang"", Y-C. Hsu"", S. Y Wu"", W. H. Li"", and J. W. Lynn'"5 Vectorially-Oriented Protein Monolayers: Neutron Reflectivity Studies

J. K. Blasie2'", L. Kneller2'", E. Nordgren2'", J. Strzalka2'", and A. Edwards2'" 56
A View of the Dynamical Changes in the IVIolten Globule-Native

Folding Step of a-Lactalbumin

Z. Bu'i=, D. A. Neumann ''^5, S.-H. Lee"s 'os, c. M. Brownisf los^ D. M.

Engleman-'33, and C. C. Han"5

CHEMICAL PHYSICS OF MATERIALS

A Quasi-Elastic and Inelastic Neutron Scattering Study of Hydrogen

in Zeolite

P. E. Sokol'", D. Narehood"-, R. M. Dimeo'», J. DeWall"', and Y. Yoshida"? The Boson Peak in Solid-State Lysozyme

A. M. Tsai^"^ C. L. Soles"^ R. M. U\meo'°^ R. L. Cappellettii»5, and D. A. Neumann"^ Cage Dynamics of (RS\Q^ (R=H, CH3, C^Hj and /f=8,10,12...)

C. M. Browni3s.io5 c. L. So\es''=, and J. D. Lichtenhans^ Diffusion of in C^o

S. A. FitzGeraldi26 d. Sethna^^^ Z. Chowdhuriiss ^os^ and D. A. Neumann'fs

Diffusion and Structural Relaxation in Viscous Sodium Disilicate

A. Meyeri=5 Dynamics of Arsenic-Selenium Glasses

B. E. Schwickert'-, R. L. Cappellettii°5, and W. A. Kamitakaharaio^ Dynamics of CufNICNyz-Pyrazine

C. M. Brown'ss 'osgnd J. L. Manson-* Dynamics of Filled Polymers

A. I. Nakatani''=. R. D. Ivkov'^^ P. Papanek2io and K. Kwan^i The Dynamics and Glass Transition in Ultra Thin Polymer Films

C. L. Solesi'5, R. M. Dimeo'K, C. M. Brown^^ ios^ and W.-L. Wu"^

The Dynamics of Hydrogen Bonded Guanidinium Based Materials

A. Pivovar2C3. D. A. Neumannics, T. Yildirimi«, C. M. Brown and M. Ward'- Dynamics of Hydrogen in Laves Phase Hydrides

A. V. Skripov38, J. C. Cooki»io5^ and T. J. Udovic'os The Dynamics of Hydrogen in Mesoporous Silica T J. Pinnavaia*=, M. Gutmann^^ S. J. L. Billinge^", C. M. Brownish- 105, and

D. A. Neumann'- The Dynamics of Hydrogen in Single-Walled Nanotubes

C. M. Brown'M T. Yildirirn'os, D. A. Neumann'os, M. J. Hebeni«, T. GennetP^ A. C. Dillon^^ J. L. Alleman?', and J. E. Fischer2") Dynamics of Layered Silicates: Intercalated Water

N. Wada'"5 and W. A. Kamitakahara"'^' Dynamics of Li-Doped Carbon Electrode Materials R Papanek^i'J 1^5, j. e. Fischer^'^ and W. A. Kamitakaharaio^ Dynamics of Methane in Zeolites 4A and 5A

R. Bell'^', M. A. Green'-"; and C. M. Brown^s ios Dynamics of Mn[N(CNy2«pyrazine and its Deuterated Analogue

C. M. Brown"s J. L. Manson\ and J. S. Miller225 Dynamics of Selenium-Arsenic-Bromine Glasses

R. L. Cappelletti'J-'. and B. E. Schwickerf'S Dynamics of Water Absorbed in Epoxy

C. L. Soles'", R. M. Dimeo'°5, and W.-L. Wu'is Dynamics of Water in Zeolites

N. Wada'^o and W. A. Kamitakahara'°5 The Effects of Confinement on Tunneling in Methyl Iodide

R. M. Dimeo'-'5 and D. A. Neumann'fs

Effects of Solvent Damping on Side Chain and Backbone Contributions

to the Protein Boson Peak

M. Tarek2» '« and D. J. Tobias'^" Evolution of the Structure of the K^NIF^ Phases of La2.,Sr, NiO^^g With Oxidation State: Octahedral Distortion and Phase Separation

(0.2<x<1.0)

J. E. Millbum'^, M. A. Green"", M. J. Rosseinsky'3^, and D. A. Neumann'°5

First-Principles Calculations and Neutron Scattering

T, Yildirim"J^^ and 0. Gulseren2""05 First-Principles Study of the Structure and Dynamics of CgHg, SigHg, and GegHg Molecules

0. Kilic'"', T. Yildirim'05, H. Mehrez'", and S. Ciraci'^ Hydrogen Diffusion in NbCo^gHjig

A. V. Skripov88, J. C. Cook'« 'os, and T. J. Udovic'^s Hydrogen Dynamics in KgMnH^

G. Auffermann'^s, T, J. Udovic'^s, J. J. RuslT», and T. Yildirim'fs Hydrogen Dynamics in ZrBeH^ 5 T.J. Udovic'05 and B. Haubacks' Hydrogen Trapping in TaN„„„gHo„„3

M. Heene^o, H. WipP", T. J. Udovic'os, and J. J. Rush'os Inelastic Neutron Scattering Study of Al Charged With Hydrogen

T. J. Udovic'05, J. J. Rush'os, C. Buckley'TM, and H. K. Birnbaum'^s Inelastic Neutron Scattering Study of Rare Earth Trihydrides and

Trideuterides

T. J. Udovic'cs, J. J. Rush'os, and Q. Z. Huang'^'cs

Investigation of Slow Motion Dynamics in Selective Adsorption

H. Taub^"'', D. Fuhrmann20'', l. Criswel|2»i, A. Diamu20", K. W. Herwig^ R Y

Hansen'62, and R. M. Dimeo'os Low Energy Dynamics of Alkali Silicate Glasses

J. ToulouseTM and D. A. Neumann'fs Low Energy Dynamics in Polycarbonate Copolymers

C. L. Soles"-', R. M. Dimeo'"; A. R Yee, and W.-L. Wu"5 Low Energy Phonons in Nanocrystals of NijFe

A. Yue'8, B. Fultz's, hi. N. Prase's, j l. Robertson'2; and R. M. Dimeo'fs Neutron Scattering Studies of the Dynamics of Hydrofluorocarbons

Encaged in NaX and NaY Zeolites

C. Karmonik2i9, N. C. Maliszewskyj'os, T J. Udovic'fs, J. J. Rush'os, M. K. Crawford33, D. R. Corbinz, and R. R. Cavanagh"9 Neutron Scattering Studies of Hydration Reaction of Tricalcium

Silicate and Portland Cement

J. J. Thomas'2; S. A. RitzGerald'28, D. A. Neumann'os, and R. A. Livingstonsa Neutron Scattering Studies on the Vibrational Excitations and the Structure of Ordered Niobium Hydrides

B. Hauer"; E. Jansen"", W. Kockelmann"", W. Schafer''^ D. Richter''^ R. Hempelmann"^ T J. Udovic'»5, and J. J. Rush'fs Neutron Scattering Study of the Role of Diffusion in the Hydration Reaction of Tricalcium Silicate

S. A. FitzGerald'28, J. J. Thomas, D. A. Neumann'os, and R. A. Livingstones Neutron Scattering Study of the Structure of Na^Ceo as a Function of Pressure and Temperature T Yildirim'05, D. A. Neumann'"; S. F Trevino^' '"s, and J. E. Fischer2'o Neutron Scattering Study of the Dynamics of Hydrogen and Deuterium

Dissolved in Crystalline PdgSi^ T J. Udovic'°5, Q, Z. Huang '^'o; J. J. Rush'"; C. Karmonik2'9, Y

Andersson'"; and I B. Flanagan22i Neutron Scattering Study of the Freeze-Thaw Process in Portland Cement

J. C. McLaughlin's", R. L. GresssTM, D. A. Neumann'"; and R. A. Livingstonss Neutron Scattering Study of the Liquid-Glass Transition in Trimethylheptane

G. Q. Shens", J. Toulouse'; S. Beaufils2'3, B. Bonello2", Y H. Hwang2; P

FinkeTM, J. Hernandez2; M. BertaulP'; M. Maglione'", C. Ecolivet2'3, and hi.

Z. Cummins^" Neutron Spectroscopy of Single-Walled Nanotubes

P Papanek2'°.'o; J. E. Fischer^'; Z. Benes2'; and A. Clay2'" Neutron Vibrational Spectroscopy and Hopping Dynamics of H and D

inPd3PoaH(D), T J. Udovic'"; Q. Z. Huang'M 1°; and Y Andersson22' Neutron Vibrational Spectroscopy of Organic Materials

B. S. Hudson's; c. Middleton's; T Jenkins'^; Y KuzmichevaTM, S. BaronovTM, and C. M. Brown'ss 'fs Neutron Vibrational Spectroscopy of Sr^lrHg and Sr^RuHg T J. Udovic'«and R. 0. Moyer'" Phonon Densities of States of y-Ce and 5-Ce Measured by Inelastic Neutron Scattering

M. E. Manley'8.80, R, j. McQueeneyTM, J. L. Robertson'2; B. Fultz'; and D.

A. Neumann'"5

NIST CENTER FOR NEUTRON RESEARCH 57
Phonon Density of States in Sc^fWO^jj

C. BroholnT' ^o^ C. Ulrich?', G. Gasparovic'\ and C, M. Brown"9.i»5 Plionon Density of States of U-238

M. E. Manleyi8'8o, R. A. RobinsonTM, C. M. Brown'99,105^ and B. Fultz's Polarization and Structural Transitions of Irradiated Vinylidene

Fluoride-Trifluoroethylene Copolymer

E. Balizerio2, A. S. DeReggi'i^, d. A. Neumann'o-', and F. B. Bateman"i

Preferential Isotopic Site Occupation in Rare-Earth Hydrides

T. J. Udovic'os, Q. Z. Huangi» and J. J. Rush"» Pressure-Induced Interlinking of Carbon Nanotubes

T. Yildirimi°5, 0. Gulseren^i" and S. Ciracii^ Proton Diffusion in Cs2(HS04)(H2P04)

S. M. Haileis, C. Chisolmia, Z. Chowdhuri'99 i"5^ T. Yildirimi^^ and D. A. Neunnann'os Proton Diffusion in Mf(S04)i„(Se04)„ /W=Rb,Cs

T. YildirinRi*, Z. Chowdhuri"^ '"s, S. M. Haile'e, C. Chisolm's, D. A. Neumann^o^ and T. J. Udovic'os Proton Dynamics in Brown IVIillerite-Structured Ba^lnjO^^gH^g: A

Combined Inelastic Neutron Scattering and Theory Study

T. Yildirim'05, D. A. Neumanni°5, and T. J. UdoviQios Proton Dynamics in Hydrated Nations

T. J, Udovici»5, S. F Trevino^ S. K. Young", M. K. Crawford^J, and Q. Sun33 Proton Dynamics in Strontium Cerate and Zirconate Ceramics

T. Yildirim'os, T. J. Udovicws, c. Karmonik^", j. j. Rushio^, and R. L. Paul'"^ Quantum Dynamics of Hydrogen in a Confined Potential

T. Yildirim'°5 and A. B. Harris^'o The Role of Particle Size in the Hydration Reaction of Tricalcium

Silicate

J. C. McLaughlini2^, D. A. Neumanni°5, and R. A. Livingstones Rotational Dynamics of Cgg in Superconducting KjBajCgo

S. Margadonna^i^ W. Z. IP^ K. Prassides^'^, and D. A. Neumann'os Sorption of Gases Into Single-Walled Carbon Nanotubes

T. Yildirimios, C. iVl. Brown'^'o^^ D. A. Neumann'os, and J. E. Fisclier2i'' Structural Ordering and Dynamics in LaH(D)3.,

T. J. Udovic'05, Q. Z. Huang'»io^ C. Karmonil<^^"^ and J. J. Rushios

Structural Symmetry of YD3 Epitaxial Thin Films

T. J. Udovici°5, Q. Z. Huang'99 '05, R. w. Erwin'os, b. Hjorvarsson226, and R. C. C. Ward226 Structure and Dynamics of Amorphous Carbon

P. Papanel<2'o 105^ W. A. Kamitakaharaio^ and J. E. Fischer^'" Structure and Dynamics of Hydrogen in HaS'm

S. A. FitzGeraldi28, T. Yildirimios, l. J. Santodonatoi°5, and D. A. Neumanni"5

Structure and Dynamics of Thallium and Tellurium Containing Low

Thermal-Conductivity Materials

B. Wolfing82, C. M. Brown'ss.'os and B. BattlogsJ Structure and Dynamics of an Ultra Hard Carbon

W. A. Kamitakaharai°5, S. F Trevino^. io5,and S. G. Buga^' Time-Temperature Superposition of Structural Relaxation in a Viscous

Metallic Liquid

A. I\/leyer'63, R. Buschi^, and H. Schoberss Two and Three Dimensional Rotons in Ordered Porous Media

P E. Soko|i3', D. Narehoodi3?, and R. M. Dimeoi»^ Vibration of Dodecahedrane: A Combined Neutron Scattering and

Theoretical Study

T. Yildirmios, B. S. Hudsonis^, and C. Middletoni^ Vibrational Densitites of States for Cubic and Hexagonal Boron Nitride

W. A. Kamitakaliara'05, D, A. Neumann'*, G. Dollys, B Sweeting^, and A. W. Moore' Water Dynamics in Monosaccharide Solutions

M. Feeney'^o, C. M. Brown^aios, a. M. Tsai"», D. A, Neumann'os, and P

Debenedetti'"" Water Dynamics in Saturated MCM-41

F Mansour225, R. M. Dimeo'fs, and Fi. Peemoeller225

X-ray Diffraction Study of the Hydration Reaction in Tricalcium Silicate

J. C. McLaughlin'2'', S. A. FitzGeraldi28, D. A. Neumann'^s, and R. A. Livingston39

INSTRUMENTATION

Assembly and Testing of the Filter Analyzer Spectrometer

A. W. Clarksoni'K, D. J. Pierce'os j. D. Reardon'|», S. Slifer'»5, and G. M.

Baltic'05 Data Acquisition and Analysis Software for the Backscattering

Spectrometer

N. C. Maliszewskyj'05 and R. M. Dimeo'* Data Acquisition and Analysis Software for the Filter Analyzer Neutron Spectrometer and the Ultra Low Angle Neutron Spectrometer

N. C. Maliszewskyj'05 Data Acquisition Electronics for the DCS

J. B. Ziegler* Data Acquisition Software for the DCS

N. C. Maliszewskyj'»5 Data Analysis Software for the Fermi Chopper Spectrometer

T. Yildirim'°5 and C. M. Brownwos

Data Reduction and Analysis Software for the DCS

J. C. Cook'o^and J. R. D. Copley'os Design of the Next Generation Cold Neutron Triple Axis Spectrometer

C. W. Brocker^sjos^ c. L. Broholm'' '05^ and Y Qiu"

Design of the Filter Analyzer Spectrometer

D. J. Pierce'05 and J. T. Kenney'^s Design of Infrastructure Improvements to the Disk Chopper

Spectrometer

C. W. Brocker"9,io5 and J. Bailey'^s Design and Performance Testing of an Active Double Focusing

Monochromator System

S. A. Smee"9.io5^ j q OrndorfP', G. A. Scharfstein'', R C. Brand'*, and C.

L. Broholm'"05 Design and Performance Testing of the DCS Data Acquisition System

Electronics

J. B. Ziegler'*, N. C. Maliszewskyj'*, and P Klosowski'os Design of the Perfect Crystal SANS Diffractometer

J. J. Moyer'* and J. T. Kenney'*

Design and Testing of Vertically Polarized Heusler Alloy

Monochromator/Analyzer

C. P. Aclams'»'*ancl J. W. Lynn'os Development of a Bent Silicon Crystal Monochromator and Other

Intensity Enhancements for the Diffractometer for Residual Stress Measurement, Texture Determination and Single Crystal Diffraction

H. J. Prask'*, T. Gnaupel-Herold'^ '*, J. G. LaRock'*, and M. P Popovici2M

Development of a Dance Floor and Air Pad System for the Next Generation Neutron Scattering Instruments

M. Murbach'99.'05, d. Pierce'*, C. W. Wrenn'»'*, and P C. Brand'* Development and Design of the Next-Generation Triple-Axis

Spectrometer

C. W. Wrenn'99 '*, M. Murbach'^ios^ p c. Brand'*, and J. W. Lynn'*

Development and Installation of a Leak-Tight, Top-Loading, Horizontal

Field Superconducting Magnet

D. C. Dander'*, R. W. Erwin'*, and S. M. Choi'^s '* Development of Low Activation Sample Holders for use at Small Angle

Neutron Scattering and Spin Echo Spectrometry Instrumentation

D. B. Fulford'* Development of a Radially-Focussed Polarizing Supermirror Analyzer

Array

J. J. Moyer'*, P C. Brand'*, and N. RosoV* Development of a Robust Static Thermal Switch for Fixed Sample

Environment Temperatures From 15-650K

L. Santodonato'* and P C. Brand'* Development of the HFBS Doppler Drive

R. M. Dimeo'*, R 0. Brand'*, and M.J. Rinehart'*

58
Development of a Vacuum Rated Preampljfjer/Ampiifi8r/-Discrimjnator

for ^He Neutron Detectors

J. B. Ziegleros The Disk Chopper Time-of-Flight Spectrometer (DCS)

J. R. D. Copleyi°5, j. C. Cook'99 i°5,

F. B. Altorfer^e, G. M. Baltic'os, P. Brandi"5,

C. W. Brocker'M D. L. C\em'°\ W. R. Clowio^, w. E. Dickerson^fs, M. C.

Englishics, P. D. Gallaghe^os, A. E. Heald^s, R Klosowskiios, w. C. Knill'os, D. L. Kulpios, H. P Layeros, N. C. Maliszewskyjifs, D. J. Piercei°5, J. Rabiger«, J. D. Reardoni»5, M. J. Rinehartio=, I. G. Schroder°5, L. A. Shuman'os, s. Slifer°5, T.

T. Thaiios, p J. Tobini»5, and J. B. Ziegleros Dy-Foil Detection of Neutrons

Y.-T. Cheng'o^ B. H. Tobyio^, and T. Gnaupel-Heroidi^S'ifs Evaluation of New Neutron Area Detectors

Y. T. Cheng'fM The Filter Analyzer Spectrometer

D. A. Neumann"5, p Papanek^io i"^J. E. Fischer2i°, J. J. Rushifs, M. L. Klein2i°, A. C. CheelhamiM, and T.J. Udovic^cs Gas Handling System for the DCS

R BrandiK, C. W. Brockeri»5, M. C, English'is, and S. Siiferos A Helium Cooling System for the Electromagnetic Field Correction

Coils of the Neutron Spin Echo Spectrometer

P C. Brandons, R D. Gallaghefi^s, D. B. Fulford'os, and W. R. Clowifs Hydrogen Cold Source Development

R. E. Williams'", R A. Kopetka'^^, and J. M. Rowers

Infrastructure Improvements in the Reactor Confinement Building

D. B. Fulfordi°5, M. G. Englishios, and P D. Gallagherio^

In Situ Real-Time Neutron Beam Imaging

K. T. Forstner"5 and N, C. Maliszewskyjics

Installation of Dedicated Crystal Alignment Spectrometer at BT-7 Beamline for Construction of FANS Double Focusing Copper

Monochromator

K. T. Forstner'^'= and A. W. ClarksoniJ=

' Installation of a New Heusler Alloy Polarizing Analyzer for BT-2

K. T. Forstner", j. A. Borchers'fs, and J. W. Lynnios

Installation of the Sample Chamber, Flight Chamber and Detector Assembly for the DCS

C. W. Brocker^s 105^ M J. Rineharti", G. M. Baltic'os, and S. Slifer" Installation and Testing of the New Thermal Beam Tube Shutter Design

Using a Remote Actuated Cast System

J. J. Moyer'05, c. W. Wrenn"9.io5, p c, Brandi»5, A. W, Clarksoni", G. M.

Baltic'°5, D. L. C\m'°^, M. J. Rineharros, and S. Slifer»5 MBE Chamber for In Situ Neutron Scattering: Instrument Development

J. A. Dura'»5 Mechanical Solution to Reduce Velocity Selector Vibrations P C. Brandi"5 and J. Baileyi»= Modular Electronics Package for Stepper Motor Operation

D. L. Kulp'^J^ M. C. Englishios, P Klosowskii«5, and N. C. Maliszewskyji»5 Monte Carlo Methods for Nuclear Applications

R. E. Williamsios Neutron Scattering Properties and Materials Properties Testing of the

Null Scattering Titanium Alloy to be Used for High Pressure Cells

S. F Trevinos K. T. Forstner'», and R. Fields'" The NIST Neutron Spin Echo Spectrometer (NSE)

N. Rosov'"5, S. Rathgeber'* 105, and M. Monkenbusch"" The Perfect Crystal SANS Diffractometer

J. G. Barkercs, j. j, Moyer", and C. J. Glinka'cs Reassessment of NG-3 Optical Filter Performance Based on

Supermirror Reflectivity Data

J. C. Cook'99 '05 SANS Polarization Analysis With Nuclear-Spin-Polarized ^He

T, R. Gentile'", G. L. Jones'", A. K. Thonnpson'", J. G. Barker'*, Q. J. Glinka'°5, B. Hammouda'"5, and J. W. Lynn'^s Search for Effects on Neutron Transmission Due to Multiple Reflection by Glass Capillary Walls

R, E. Beneson'06.232^ H. H. Clien-Mayer'»e, and J. W. Lynn'fs

TANQENS-A New Utility for the Analysis of Quasielastic Neutron

Scattering Data

T. Yildirim'os

NEUTRON PHYSICS

Accelerated Testing for Neutron Induced Soft Errors in SRAM Chips

A. K. Thompson"' and J. F Ziegler'^e Accurate Determination of Neutron Capture Flux

M. S. Dewey'", M. Arif", D. M. Gilliam'", J. S. Nico'", W. M. Snow^s, J, Pauwels65, and R. ScotF Benchmark Measurements and Calculations of Neutron Transport

D. M. Gilliam'", M. S. Dewey'", J. S. Nico'", 0. M. Eisenhauer'", J. A. Grundl'", and H. Gerstenberg^ Certified Neutron Fluence Standards From the Cavity Fission Source

J. M. Adams'" and J. A. Grundl'" Defined-Geometry Alpha Counting

D. M. Gilliam'" and J. S. Nico'" Determination of the Neutron Lifetime

M. S. Dewey'", J. S. Nico'", D. M. Gilliam'", W. M. SnowTM, and R R. Huffman'" Highly Accurate Neutron Wavelength Measurements

M. S. Dewey'", K. J. Coakleys, W. M. Snow^s, M. Arif", D. L. Jacobson'", and S. A. Werner2«'' Intercomparison of NIST and PNL Calibration Facilities

A. K. Tfiompson'", R. B. Schwartz'", J. McDonald", and M. Murphy"

LASER Polarization of ^He for Neutron Spin Filters and Medical MR!

A. K. Thompson'", T R. Gentile'", M. S. Dewey'", G. L. Jones^", F E. Wietfeldt'" ^', W. M. Snow^s, and D. R. Rich'" Neutron Calorimetry

W. M. SnowTM, Z. Chowdhuri'»'05, j. s. Nico'", M. S. Dewey"', and G. Hansenss Neutron Fluence Rate Measurements

D. M. Gilliam'", J. S. Nico'", and J. M. Adams'" Neutron Interferometry and Optics

M. Arif", D. L. Jacobson"', R. Clothier'3, A. K. Thompson'", S. A. Werner2»'', A. loffe2M"', A. Zollinger'*, K. Raum206, B. Schillinger206, Q. Rausch2<'6, and

W. Richardsas Neutron Radiography/Tomography T R. Gentile'", M. Arif", and D. L. Jacobson'"

Parity Non-Conserving Neutron Spin Rotation

B. Hecke|22'', D. Markoff22^ E. Adelberger22'', F E. Wietfeldf " =', and P R. Huffman'" Quality Assurance Checks on Masses and Impurities in Neutron Dosimeters for NRC Reactor Pressure Vessel Embrittlement

Surveillance

J. M. Adams'", D. M. Gilliam'", and J. A. Grundl'" Response of Albedo Dosimeters Versus Distance From a Neutron Source

R. B. Schwartz'" and A. K. Thompson'"

Study of Time Reversal Invariance in Neutron Beta Decay

J. Wilkerson229, J. S. Nico'", R. G. H. Robertson'TM, S. Freedman'TM, A.

Garcia2»9, K. Coulter's, m. S. Dewey'", A. K. Thompson'", B. Fujikawa''^ G. L. Jones '"'58, J. M. Adams'", F E. Wietfeldf " s', L. Lising"8, and T Steiger22'' Trapping of Ultra Cold Neutrons

J. M. Doyle^', S. K. LamoreauxTM, R. Golub«, M. S. Dewey'", P R. Huffman'",

C. R. Bromes', C. E. H. Mattoni^', D. N. McKinsey^', K. Alvine^', S. Dzhosynk^',

L. Yans'g, K. Coakley'", G. Yang'", and A. K. Thompson'"

Utilization of the Materials Dosimetry Reference Facility-Tests of New

IRMM 237Np and ^^su Fast Neutron Dosimeters

J. M. Adams'", J. A. Grundl'", C. M. Eisenhauer'", D. M. Gilliam'", and R

Simpson'8

NiST CENTER FOR NEUTRON RESEARCH 59
MATERIALS ANALYSIS

Analytical Applications of Cold Neutrons

H. H. Chen-Mayer*, R. Demiralp'*, R. R. Greenbergios, G. R Lamazei*, J. K. Langland^of', r. m. Lindstromi*, e. A. Mackeyi", D. R R. Mildner'*, R. L. PauP06, and V. A. Sharov232 Application of Radioisotope-lnduced X-ray Emission to the

Identification of Lead and Other Elements in Ceramic Glazes and Housewares

D. L. Anderson''^ and W. C. Cunningham^

Archeological Applications of NAA

R. Bishopi55 and M. J. BlackmanTM A Bender-Focuser for Prompt Gamma Activation Analysis

E. A. Mackey'06, H. H. Chen-Mayer^*, R. M. Lindstromi*, D. R R. Mildner'*,

R. L. Paupo6, Q.-F. Xiao222, andV. A. Sharov^s^ Bio-Analytical and Specimen Bank Research

R. R. Greenbergi*, J. K. Langlandi*, E. A. Mackeyi*, B. J. Porter'*, and R.

L. Zeisler'* Certification of Standard Reference Materials by Neutron Activation Analysis

D. A. Becker'*, R. Demiralp'*, R. R. Greenberg'*, R. M. Lindstrom'*, E. A. Mackey'*, and R. L. Zeisler'* Characterization of Sources and Fluxes of Particulate Pollutants Depositing to Great Waters R R Caffrey'M, A. E. Suarez'*, and J. M. OndoV*

Characterization of Submicrometer Aerosol Particles

J. M. Ondov'w, S. F. Heller-Zeisler''w, and R. L. Zeisler'* Determination of Hydrogen by PGAA

R. R. Greenberg'*, R. M. Lindstrom'*, and R. L. Paul'* Determination of Phosphorus via RNAA vifith Beta Counting

R. L. Paul'* Evaluation of Accuracy and Precision in INAA of Botanical Materials

D. A. Becker'* Evaluation of Errors and Interferences in NAA

D. A. Becker'*, M. J. Blackman'^s, R. R. GreenbergTM, R. M, Lindstrom'*, and

R. L. Zeisler'* Focusing Methods for Radiography and Topography

H. H. Chen-Mayer'*, D. R R. Mildner'*, K, M. Podurets's V. A. Sharov232, and

S. S. Shilstein'5 High Sensitivity Gamma-Ray Spectrometry

R. M. Lindstrom'* and G. P Lamaze'* Homogeneity and Composition of Small Solid Samples

R. L. Zeisler'* Hydrogen Detection in Industrial Materials by Incoherent Neutron

Scattering

H. H. Chen-Mayer'*, V. V. Kvardakov'^ D. R R. Mildner'*, V. A. Somenkov's, and D. Kozlenko'^ Improvements to INAA Methodology

D. A. Becker'*, R. Demiralp'*, R. R. Greenberg'*, R. M. Lindstrom'*, E. A. Mackey'*, and R. L. Zeisler'* Improvements to PGAA Methodology

D. L. Anderson^2, R. M. Lindstrom'*, E. A. Mackey'*, and R. L. Paul'* Measurement of Lithium Concentrations in Battery Materials with Cold Neutron Depth Profiling

G. R Lamaze'*, H. H. Chen-Mayer'*, D. A. Becker'*, A. Gerouki"2, R

Vereda"2, N. Clay"2^ r Zerigian'72, and T. Haas"2

Multielement Analysis of Foods and Related Materials by NAA

D. L. Anderson* and W. C. Cunninghami2 Neutron Absorption Measurements Using Converging Beams

H. H. Chen-Mayer^*, E. A. Mackey'*, D. R R. Mildner'*, and R. L. Raul'* Neutron Beam Spatial Distributions Using Imaging Plate Technology

H. J. Bahre"5, H. H. Chen-Mayer'*, Y.-T. Cheng'o"-'*, D. F R. Mildner'*, and

V. A. Sharov232 Neutron Depth Profiling of AIN Thin Films

H. H. Chen-Mayer'*, G. P Lamaze'*, and S. McGuire28 Neutron Depth Profiling of Sulfur in CVD Diamonds

H. H. Chen-Mayer'*, G. P Lamaze'*, L. Pilione'^?, and B. Weiss2'2 Nitrogen Profiling of Thin Titanium Nitride Films

G. P Lamaze'*, H. H. Chen-Mayer'*, N. Cox*, and E. B. Steel"^ Neutron Focusing for Analytical Chemistry

H. Chen-Mayer'*, G. P Lamaze'*, J. K. Langland'*, R. M. Lindstrom'*, E. A. Mackey'*, D. R R. Mildner'*, V. A. Sharov232 and J. R. Swider"^ Neutron Distribution Measurements by Neutron Induced Autoradiography

Z. En222, J. s. Brenizer222. and D. A. Becker'* Neutron Dosimetry for Instrument Development

R. M. Lindstrom'* Neutron Transmission Through Tapered Capillaries

H. H. Chen-Mayer'*, D. R R. Mildner'*, and V. A. Sharov232 New Developments in Monitor Activation Analysis

G. P Lamaze'*, R. M. Lindstrom'*, and R. L. Paul'* New Developments in NDP

H. H. Chen-Mayer'*, G. P Lamaze'*, and J. K. Langland'*

Quality Assurance Improvements for NAA

D. A. Becker'*, R. Demiralp'*, R. R. Greenberg'*, R. M. Lindstrom'*, E. A. Mackey'*, and R. L. Zeisler'* Quality Assurance Programs

D. L. Anderson* and W. C. Cunningham*

Reactor Characterization for NAA

D. A. Becker'* Redesign of the VT-S Thermal Neutron Prompt Gamma-Ray Activation Analysis Facility

E. A. Mackey'*, R. M. Lindstrom'*, D. L. Anderson*, R J. Liposky'*, G. D.

Reilly'*, D. R. Brown"'', and M. A. Suthar'* Radionuclides in Foods

D. L. Anderson* and W. C. Cunningham*

Revalidation of Food SRMs

D. L. Anderson* and W. C. Cunningham*

Size Distribution and Deposition of Toxic Elements to Lake Michigan,

by Size and by Source P F Caffrey'''^ and J. M. Ondov'^s Test of a Novel High Sensitivity Neutron Detector

B. Felleri25, H. H. Chen-Mayer'*, and G. Lamaze'*

60 EESEARCH TITLES
AFFILIATIONS:

1 Advanced Ceramics Corporation

2 AEA Technology, United Kingdom

3 Alcoa Technical Center

^ Argonne National Laboratory

5 Armed Forces Radiobiology Research Institute

6 Army Research Laboratory

^ Army Research Office

8 Auburn University

3 Australian Geological Survey,

Australia

1" Australian Nuclear Science and

Technology Organization, Australia " Battel le Pacific Northwest

Laboratory

12 Belarus Academy of Sciences,

Belarus " Bethany College

Bilkent University, Turkey

15 Brookhaven National Laboratory

16 Brooklyn Polytechnic University Brown University

18 California Institute of Technology " Carnegie Mellon University

2° Center for Advanced Research in Biotechnology

21 Centre National de Recherche

Scientific, France

22 Centre Brasileiro de Pesguisas

Fisicas, Brazil

23 Chalk River Laboratories, Canada

2" City College of New York

25 Clemson University

25 College of William and Mary

2' Commissariat d'Energie Atomique,

France

V 28 Cornell University

25 Czechoslovakia Academy of Sciences, Czechoslovakia

3» Darmstadt Technology University, Germany

31 Dow Corning

32 Dow Chemical

33 Dupont Company

3^ Dupont Experimental Station, Wilmington

35 Eidgendssische Technische Hochschule, Switzerland

38 Emory University School of Medicine

3' ExxonMobil Research and

Engineering Company

38 Englehard Corporation

39 Federal Highway Administration

^8 Florida Atlantic Univrsity

^1 Florida State University

"2 Food and Drug Administration " Ford Motor Company

^ Forschungzentrum JOIich GmBH,

Germany

"5 Fuji Medical Systems USA,

Incorporated * General Electric Corporate Research

General Electric, Salem * General Motors Research and Development Center

"5 Hahn-Meitner Institute, Germany

8" Hamilton College

81 Harvard University

82 Hamburger

Synchrotonstrahlungslabor HASYLAB at Deutsches

Elektronen-Synchrotron DESY

Germany

83 Hongik University, South Korea

-J Hybrid Plastics

88 IBM, Almaden

88 Idaho National Engineering and

Environment Laboratory

8' Imperial College, United Kingdom

88 Indiana University

88 Institut Laue-Langevin, France

8" Institut Fur Physikalische Chemie,

Germany

81 Institute for Energiteknikk, Norway

82 Institute of Physical and Chemical

Research, Japan

83 Institute of Physics, Peoples

Republic of China

8^ Institute for Plasma Physics, Czech Republic

88 Institute for Reference Materials and Measurements, Belgium

88 Institute for Special Materials, Italy

8'' Institute for Superhard and Novel Carbon Materials, Russia

88 Intel Corporation

89 loffe Physica-Technical Institute, Russia TM John Deere Corporation

^1 Johns Hopkins University

'2 Joint Institute of Nuclear Research, Russia

'3 Karlsruhe Nuclear Research

Center, Germany

Kent State University

'8 Kurchatov Institute, Russia

'8 Kyoto University Japan

Ti Kyunghee University Korea

'8 Lehigh University

'9 Leiden University, Germany

88 Los Alamos National Laboratory

81 Los Alamos Neutron Science

Center

82 Lucent Technologies, Bell Laboratories

83 Massachusetts Institute of Technology ^ Max-Planck Institut, Germany

85 McClellan Nuclear Radiation Center

86 McMaster University, Canada

87 MDK Incorporated

88 Metal Physics Institute, Russia

89 Michigan Molecular Institute

98 Michigan State University

91 Moscow State University, Russia

92 Moscow Steel and Alloys Institute, Russia

93 National Aeronautics and Space

Administration, Johnson Space

Center

9" National Central University Taiwan

95 National Institute for Research in Inorganic Materials, Japan

98 National Institute of Health

9' National Renewable Energy

Laboratory = National Sun Yat-Sen University Taiwan

99 National Taiwan University, Taiwan = National Tsing Hua University Taiwan

181 Naval Research Laboratory

182 Naval Surface Warfare Center

183 NEC Research Institute Incorporated

18" Neutek Incorporated

185 NIST Center for Neutron Research

188 NIST Analytical Chemistry

Division

19' NIST Biotechnology Division

188 NISI Building Materials Division

iM NIST Ceramics Division

110 NIST Electron and Optical Physics

Division

111 NIST Ionizing Radiation Division

112 NIST Materials Reliability Division

113 NIST Metallurgy Division

11" NIST Occupational Health and

Safety Division

118 NIST Polymers Division

118 NIST Semiconductor Electronicis Division

1" NIST Standard Reference

Materials Program

118 NIST Statistical Engineering

Division

119 NIST Surface and Microanalysis Science Division NIST Thermophysics Division

121 North Carolina State University

122 Northeastern University

123 Northern Illinois University

12" Northwestern University

125 Nova Scientific, Incorporated

128 Oak Ridge Institute for Science and Education

12' Oak Ridge National Laboratory

128 Oberlin College

129 Ohio State University

138 Ohio University

131 Olin Conservation Incorporated

132 Oregon State University

133 OSMIC, Incorporated

13" Oxford University, United Kingdom

135 Pacific Lutheran University

138 Paul Scherrer Institute, Switzerland

13' Pennsylvania State University

138 Philips Research Laboratories, The

Netherlands

139 Polytechnic University

i"8 Princeton University

i"i Purdue University

i"2 Queen's University Canada

i"3 Racah Institute, Israel

1"" Ris0 National Laboratory Denmark

i"5 Rice University

i"8 Royal Institute of Technology Sweden

1"' Royal Institution, United Kingdom

i"8 Ruhr University Germany

i"9 Russian Academy of Sciences, Russia

188 Rutgers University

151 SAGE Electrochromics

182 Sandia National Laboratory

153 Seoul National University, Korea

18" Sid Richardson Carbon Company

185 Smithsonian Institute

158 Stanford University

18' State University of New York, Stony Brook

188 Stress Sensors

189 Syracuse University

189 Tata Institute of Fundamental

Research, India

181 Technology for Energy

Corporation

182 Technical University of Denmark, Denmark

183 Technical University Munchen,

Germany

18" Technobiochip

185 Tel Aviv University Israel

188 Texas Materials Institute

18' Thomas Jefferson High School

188 Tohoku University, Japan

189 Tokyo University Japan

"8 Toyo University Japan

i'i Trinity College

1'2 Tufts University

1'3 Universita' di Brescia, Italy

1'" University des Saarlandes, Germany

i'8 University of Aachen, Germany

i'8 University of Akron

1" University of Bourgogne, France

1'8 University of California at Berkeley

i'9 University of California at Davis

188 University of California at Irvine

'81 University of California at Riverside

182 University of California at San

Diego

183 University of California at San

Francisco

18" University of California at Santa

Barbara

185 University of California at Santa Cruz

186 University of Chicago

18' University of Cincinnati

188 University of Cologne, Germany

189 University of Connecticut

198 University of Delaware

191 University of Florida

192 University of Grenoble, France

193 University of Guelph, Canada

19" University of Houston

195 University of Illinois

198 University of Innsbruck, Austria

19' University of Iowa

198 University of Manitoba, Canada

199 University of Maryland at College

Park

288 University of Maryland Baltimore County

291 University of Massachusetts

292 University of Michigan

283 University of Minnesota

29" University of Missouri at Columbia

298 University of Missouri-Rolla

298 University of Munich, Germany

29' University of Nebraska

288 University of New Hampshire

289 University of Notre Dame

218 University of Pennsylvania

211 University of Pierre and Marie

Curie, France

212 University of Puerto Rico

213 University of Rennes, France

21" University of Rhode Island

215 University of Surrey United Kingdom

218 University of Sussex, United Kingdom

21' University of Sydney Australia

218 University of Tennessee

219 University of Texas

220 University of Utah

221 University of Vermont

222 University of Virginia

223 University of Warsaw, Poland

22" University of Washington

225 University of Waterloo, Canada

228 Unversity of Uppsala, Sweden

22' Virginia Commonwealth University

228 Walter Reed Army Institute of Research

229 Washington University

239 West Virginia University

231 Worcester Polytechnic Institute

232 X-ray Optical Systems

233 Yale University

NiST CENTER FOR NEUTRON RESEARCH 61
PUBLICATIONS

Abdurashitov, J. N., Gavrin, V, N.. Girin, S. V., Gorbachev, V. V., Ibragimova, T. V.. Kalikhov, A.V., Khaimasov. N. G., Knodel, V. N., Mirmov, I. N., Shikhin, A. A., Verentenkin, E. P.. Vermul, V. M., Yants. V. E., Zatsepin, G. T., Bowles, T. J., Teasdale, W. A„ Wark, D. L., Cherry, M. L., Nico, J. S., Cleveland, B. T., Davis, R., Lande, K., Wildenhain, P. S., Elliott, S. R.. Wilkerson, J. R, "Measurement of the Solar Neutrino Capture Rate by SAGE and Implications for Neutrino Oscillations in Vacuum," Phys. Rev. Lett. 83 (23). 4686 (1999).

Abdurashitov, J. N., Gavrin, V. N., Kalikhov, A.V., Matushko, V. L., Shikhin, A. A., Yants, V. E., Zaborskaia, 0. S., Adams, J. M., Nico, J. S., Thompson, A. K., "A

High Resolution Low Background Fast Neutron Spectrometer," in Proceedings of the Internationa! Workshop on Neutron Field Spectrometry in Science. Technology,' and

Radiation Protection (Pisa, Italy, June 2000), in press.

Adams, C. P, Lee, Y S., Lee. S. ~H., Lynn, J. W., "Triple-Axis Research at NIST," Neutron News, in press.

Adams, C. P. Lynn, J. W., Mukovskii, Y. M., Arsenov, A. A., Shulyatev, D. A., "Charge

Ordering and Polaron Formation in the Magnetoresistive Oxide La„7Ca„ ,MnO,,"

Phys. Rev. Lett., in press.

Adams, J. M., "Results From the NIST Round Robin Test of Fissionable Dosimeters in a Reactor Leakage Spectrum," REACTOR DOSIMETRY, in Proceedings of the Tenth

International Symposium on Reactor Dosimetiy. Sept. 12- 17. 1999. in press.

Adams, J. M., "The Neutron Source Calibration Program at the National Institute of Standards and Technology," in Transactions ofthe American Nuclear Society, San

Diego, CA, 82 106 (2000).

Adams, J. M., Greenhouse, L. A., "Nuclear Science at the National Institute of Standards and Technology: A Historical Overview." in Transactions of the American Nuclear

Society, Winter Meeting. November 2000, (Washington, DC), in press.

Agnew, S. R.. Elliott, B. R.. Youngdahl, C. J., Hemker, K. J., Weertman, J. R., "Structure and Mechanical Properties of Nanocrystalline Metals—With Opportunities

for Modeling," 19"^ Ris0 International Symposium on Materials Science. Rise

National Laboratory, Roskilde, Denmark, in press.

Alexandridis, P., Yang, L., "Micellization of Polyoxyalkylene Block Copolymers in Formamide" Macromol. 33 (9), 3382 (2000).

Alexandridis, P., Yang, L., "SANS Investigation of Polyether Block Copolymer Micelle

Structure in Mixed Solvents of Water and Fomiamide, Ethanol, or Glycerol," Macromol. 33 (15). 5574 (2000).

Allman. B. E.. McMahon. P J.. Nugent. K. A.. Paganin. D., Jacobson, D. L.. Arif, M.,

Werner, S. A.. "Quantitative Phase Radiography with Neutrons," Nature, in press.

Amis. E. J.. Bauer, B. J., Topp, A., Groehn, P., Prosa, T. J., Viers, B. D., Liu, D. W.,

Barnes, K. A., Jackson, C. L., Nisato, G., Karim, A., Douglas, J. P., "Preparation and

Characterization of Polymer/Dendrimer Blends," NISTIR 6506.

Anderson, C. R., Stirling, W. G., Andersen, K. H., Sokol, P. E., Dimeo, R. M., "TwoDimensionai Excitations of Superfluid ''He Confined in 72% Porosity Xerogel," Physica B 276, 820 (2000).

Anderson, D. L., Capar, S. G., "Identification of Lead in Metal Food Can Seams Using "Co RXRFS," J. Radioanal. Nucl. Chem., in press.

Anderson. D. L., Cunningham, W. C, "Revalidation and Long-Term Stability of National

Institute of Standards and Technology Standard Reference Materials 1566, 1567,

1568, and 1570," J. AOAC Im. 83 (5), 1 121 (2000).

Anderson, D. L., Cunningham, W. C, Capar, S. G., Baratta, E. J., Mackill, P., "Nuclear Methods for Food Analysis at the U. S. Food and Drug Administration." J. Radioanal.

Nucl. Chem., in press.

Anderson, D.L.. "Neutron Capture Prompt Gamma-Ray Activation Analysis of Meat

Homogenates," J. Radioanal. Nucl. Chem. 244 (1), 225 (2000).

Bandyopadhyay, S., Tarek, M., Klein, M. L., "Molecular Dynamics Study of a Lipid- DNA Complex," J. Phys. Chem. B 103, 10075 (1999).

Bandyopadhyay, S., Tarek, M., Lynch, M. L.. Klein, M. L.. "A Molecular Dynamics

Study of the Poly (Oxyethylene) Surfactant C|,E2 and Water," Langmuir 16 (3), 942

(1999). - "

"

Bao, W., Pagliuso, P. G., Sarrao, J. L., Thompson, J. D., Fisk, Z., Lynn, J. W., Erwin, R. W., "Incommensurate Magnetic Structure of CeRhlUj," Phys. Rev. B, in press.

Barilo, S. N., Bychkov, G. L.. Kurnevich, L. A.,

Barnes, J. D.. Kolb, R., Barnes, K., Nakatani, A. I., Hammouda, B., "Microstructure Analysis Using Temperature-Induced Contrast Variation in Small-Angle Scattering,"

J. Appl. Crystallogr. 33 (1), 758 (2000).

Barnes, K. A., Karim, A., Douglas, J. F, Nakatani, A. I., Griill, Amis, E. J., "Suppression

of Dewetting in Nanoparticle Filled Polymer Films," Macromol. 33 (11). 4177

(2000).

Bateman. F. B.. Boukharouba, N., Brient, C. E., Carlson, A. D., Grimes, S. M., Haight,

. R. C, Massey, T. N., Wasson, 0. A., "New Measurements of the H(n,n)H Angular

Distribution," REACTOR DOSIMETRY, in Proceedings of the Tenth International Symposium on Reactor Dosimetry, 1999, in press.

Bauer, B. J., Amis, E. J.. "Characterization of Dendritically Branched Polymers by SANS, SAXS, andTEM," Tomalis/Frechet: Dendritic Polymers. 2000, in press.

Bauer, B. J., Ramzi, A.. Liu, D. W., Scherrenberg, R., L., Froehling, P., Joosten, J., "Blends of Fatty Acid Modified Dendrimers With Polyolefins," J. Polym. Sci. Phys. 38(1). 95 (2000).

Becker, D. A., "30 Years of Reactor Characterization on the NBSR." J. Radioanal. Nucl. Ch. 244(2), 361 (2000).

Benenson, R. E., Chen-Mayer, H. H., Lynn, J. W., "Search for Effects on Neutron

Transmission Due to Multiple Reflection by Glass Capillary Walls," in Proceedings of SPIE Annual Meeting, volume 3767 (1999), in press.

Blackman. M. J., Badaljan, R. S., Kikodze, Z. K., Kohl, P. L., "Chemical Characterization of Caucasian Obsidian; Geological Sources," in Synthese Sur VObsidienne au

Proche-Orient: Du Volcan a VOutU, (BAR Publication, London), in press.

Blackman. M. J.. Redford, S., "Northern Syrian Luster and Fritware: Petrographic and Chemical Implications for Productions and DistribuUon," Antiquity, in press.

Bode, P., de Nadai Femandes, E. A., Greenberg, R., "INAA as a Primary Method in Metrology for Chemical Measurements," in Proceedings Metrolsul. '99, in press.

Bode, P., de Nadai Femandes, E. A., Greenberg, R. R., "Metrology for Chemical Measurements and the Position of INAA," J. Radioanal. Nucl. Ch. 245 (1), 109

(2000).

Bodnar, I., Silva, A., Deitcher, R.W., Weisman, N. E., Wagner, N. J., Kim, Y. H., "Structure and Rheology of Hyper Branched Polymers and Dendritic Polymers I: Modification and Characterizarion of Poly(propyleneimine)-Dendrimers with Acetyl Groups," J. Polym. Sci. Poly. Phys. 38 (6), 857 (2000).

Bodnar. I., Silva, A., Wagner, N. J., Kim, Y. H., "Structure and Rheology of Hyperbranched Polymers and Dendritic Polymers II: Effects of Blending Acetylated and Poly(propyleneimine) Dendrimers with Aqueous Poly(ethylene oxide) Solutions,"

J. Polym. Sci. Poly. Phys. 38 (6), 874 (2000).

Borchers, J. A., Dura, J. A., Majkrzak, C. F. Hsu, S. Y, Lolee, R., Pratt, W. P,

Bass, J.. "Polarized Neutron Reflectivity Characterization of Weakly Coupled Co/Cu

Multilayers," Physica B 283 (1), 162 (2000).

Bossy, J.. Anderson. K. H., Cook, J.C., Randle, 0. R.. "High Resolution Neutron Measurements of Roton Line Shape Under Pressure." Physica B 284, 27 (2000).

Brown, A. B. D., Rennie, A. R., "Monodisperse Colloidal Plates Under Shear" Phys. Rev. E 62(1), 851 (2000).

Brown, C. M., Yildirim, T, Neumann, D. A., Heben, M. J., Gennett, T, Dillon, A. C,

Alleman, J. L., Fischer, J. E., "Quantum Rotation of Hydrogen in Single-Wall Carbon Nanombes" Chem. Phys. Lett. 329 (3), 31 1 (2000).

Bu. Z., Neumann, D. A.. Lee. S.. Brown, C. M., Engelman, D. M., Han, C. C, "A View

of Dynamics Changes in the Molten Globule-Native Folding Step by Quasielastic Neutron Scattering," J. Mol. Biol. 301 (2), 525 (2000).

62 PUBLICATIONS
Buckley. C. E.. Bimbaum. H. K.. Lin. J. S.. Spooner, S.. Bellmann, D.. Staron, P.. Udovic,

T. J., Hollar. E.. "Characterization of H-Defects in the Aluminum-Hydrogen System

Using Small Angle Scattering Techniques," J. Appl. Crystallogr., in press.

Buckley. C. E., Bimbaum. H.K., Bellmann, D., Staron, P., "Calculation of the Radial

Distribution Function of Bubbles in the Aluminum Hydrogen System," J. Alloy Compd. 295, 231 (1999).

Burton, A., Feuerstein, M., Lobo, R.F. Chan, J.C.C.. "Characterization of Cancrinite Synthesized in 1. 3-Butanediol by Rietveld Analysis of Powder Neutron Diffraction Data and Solid-State -'Na NMR Spectroscopy," Micropor. Mesopor. Mat. 30 (2-3), 293 (1999).

Burton. A.. Lobo, R. F.. "The Role of Barium Cations in the Synthesis of Low-Silica LTL

Zeohtes," Micropor Mesopor Mat. 33 (1-3). 97 (1999).

Cappelletti, R. L., "The National Institute of Standards and Technology Center for Neutron Research (NCNR)," Neutron News, in press.

Cappelletti, R. L., "Vibrational Excitations in Glasses: A: Inelastic Neutron Scattering,"

in Insulating and Semiconducting Glasses. Series on Directions in Condensed Matter

Physics, Vol. 17. edited by P. Boolchand, chapter 6A (World Scientific Publishing Co,

Singapore, 2000), p. 329.

Cappelletti, R. L.. Clutter. L. K.. edited by, "NIST Center for Neutron Research 1999 Programs and Accomplishments. MSEL," NISTIR 6437.

Cappelletti, R. L., Clutter, L. K., edited by, "NCNR 1999, NIST Center for Neutron

Research Accomplishments and Opportunities," NIST SP 944.

Cappelletti, R. L., Glinka, C. J.. Krueger, S., Lindstrom, R. A., Lynn, J. W., Prask, H.,

J., Prince, E., Rush. J. J.. Rowe, J. M.. Satija, S. K., Toby, B. H., Tsai, A., Udovic,

^ T. J.. "Materials Research With Neutrons at NIST," J. Res. Natl. Inst. Stan. Tech.,

in press.

Carpenter, J. M., Iverson, E. B., Mildner, D. F. R., "Time Focusing of Pulsed-Neutron

Source Crystal Analyzer Spectrometers," Nucl. Instrum. Meth. A, in press.

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Chen, W. C, Heuser, B. J., King, J. S., "SANS Investigation of Deuteride (Hydride)

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Izumi, F, Ikeda, T, "A Rietveld-Analysis Program RIETAN-98 and Its Applications to Zeolites," Mater Sci. Forum 321 (3), 198 (2000).

Jacobson, D. L., Arif, M., Bergmann, L., loffe, A., "Development of the Neutron Phase

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Jones. G. L.. Gentile. T. R.. Thompson, A. K.. Chowdhuri. Z., Dewey, M. S.. Snow. W.

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Jones. R. L., Kumar. S. K.. Ho, D. L.. Briber, R. M., Russell, T. P, "Chain Conformation

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Karen, P., Kjekshus, A., Huang, Q., Karen, V., Mighell, A. D., Santoro. A., "Neutron Powder Diffraction Study of the Crystal Structure of the Oxycarbonate Phase YBajCu,,5(C03)„ ,50„,," Physica C 336 (3), 279 (2000).

Keimer. B., Casa, D., Ivanov, A., Lynn, J. W., Zimmermann, M. V., Hill, J. P., Gibbs,

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Kilic, C, Ciraci, S., Gulseren, 0., Yildirim, T.. "Variable and Reversible Quantum

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Kilic, C, Yildirim, T. Mehrez. H.. Ciraci. S., "A First-Principles Study of the Structure and Dynamics of C,H, Si.Hg and Ge^H, Molecules," J. Phys. Chem. A 104 (12), 2724(2000).

Kim, S. D., Klein, A.. Sperling, L. H., Boczar E.M., Bauer, B. J., "A Direct Comparison

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Kim, S. D.. Klein, A., Sperling. L. H.. Boczar, E. M., Bauer, B. J.. "SANS Study of

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King, H. E., Butter, J. L., Lin, M. Y, Sun, T., "Polymer Conformations of Gas-Hydrate

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Kline. S. R., "Structural Evolution During Micelle Polymerization." J. Appl. Crystallogr 33(1). 618 (2000).

Kmety, C. R., Huang, Q., Lynn, J. W., Erwin, R. W., Manson. J. L.. McCall, S.. Crow,

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Kobayashi. K., Huang, C. I., Lodge, T. P.. "Thermoreversible Gelation of Aqueous

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Koehler, R. D., Raghavan, S. R.. Kaler, E. W., "Microstructure and Dynamics of Wormlike Micellar Solutions Formed by Mixing Cationic and Anionic Surfactants,"

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Koubi, L., Tarek, M., Klein, M. L., Scharf, D., "Distribution of Halothane in a Dipalmitoylphosphatidylcholine Bilayer from Molecular Dynamics Calculations," Biophys. J. 78 (2), 800 (2000).

Krishnamoorti, R., Silva, A. S., Modi, M. A., Hammouda, B., "Small Angle Neutron

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Krone, C. A., Robisch, R A.. Tilbury, K. L., Stein. J. E., Mackey, E. A., Becker, R R., O'Hara, T. M., Philo, L. M., "Heavy Metals and Other Elements in Liver Tissues of Bowhead (Balaena Mysticetus) Whales," Mar. Mam. Sci., in press.

Krueger. J, K., Gallagher. S. C, Wang. C. L., Trewhella, J., "Calmodulin Remains

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Krueger, J. K., Trewhella, J.. "Neutron Scattering Studies of Muscle Protein Structures and Their Interactions" in Molecular Interactions ofActinL Actin Structure and Actin- Binding Proteins, edited by C. G. do Remedios, D. D. Thomas, (Springer Verlag, 1999), in press.

Krueger. S., Gregurick, S., Shi, Y, Wang, S., Wladkowski, B. D., Schwarz, F. P., "Specific DNA Binding to CRP Induces a Conformational Change in CRP in Solution: A Small Angle Neutron Scattering Study," Biochem., in press.

Krueger. S., Meuse, C. W.. Majkrzak. C. F., Dura. J. A., Berk, N. F., Tarek, M.. Plant, A. L., "Investigation of Hybrid Bilayer Membranes With Neutron Reflectometry: Probing the Location of Interactions of MeUttin," Langmuir, in press.

Laraaze, G. P., Chen-Mayer, H. H., "Nitrogen Analysis in Thin Films Using Cold

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Lamaze, G. P., Chen-Mayer, H. H., Badding, M.. Laby, L.. "In Situ Measurement of Lithium Movement in Thin Film Electrochromic Coatings Using Cold Neutron Depth

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Lee. S. -H., Cheong, S. -W., Yamada, K., Majkrzak, C. F., "Charge and Canted Spin Order in La,^Sr^NiOj," Phys. Rev. B. in press.

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Livingston. R., Neumann. D. A., Allen, A. J., FitzGerald, S. A., Berliner, R., "Application of Neutron Scattering to Portland Cement," Neutron News, in press.

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Lynn. J. W.. "Magnetic Neutron Scattering," in Methods in Materials Research, edited by Kaufman (John Wiley & Sons), in press.

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Lynn, J. W., "Neutron Studies of Exchange-Coupled Superconductors," in Proceedings NATO Advanced Research Workshop (June 13-18"^), in press.

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Lynn. J. W.. Keimer. B,, UWch, C, Bernhardt, C, Tallon, J. L., "Antiferromagnetic Ordering of Ru and Gd in Superconducting RuSr,GdCUiOj," Phys. Rev. B 61 (22), R14 964 (2000).

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Lynn. J. W.. Skanthakumar. S., "Neutron Scattering SUidies of Lanthanide Magnetic

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Magid. L. J., Li, Z., Butler, P. D., "Flexibility of Elongated Sodium Dodecylsulfate

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Paul, R. L., Simons, D. S., "Neutron Activation Analysis for Calibration of Phosphorus

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Peter, S., Altorfer, F, Buhrer, W., Lutz, H. D., "Sr(OH)Br, a Metal Hydroxide Halide With

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Prask, H. J., Brand, P. C, Gnaupel-Herold, T, Hicho, G. E., "Determination of Residual

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Prask, H. J., Gnaupel-Herold. T, Clark, A. V., Hehman, C. S., Nguyen, T. N., "Neutron and Ultrasonic Determination of Residual Stress in an Aluminum Ring-Plug," in Review of Progress in Quantative NDE 19B. edited by D. 0. Thompson, D. E., Chimenti, AIP 509, (AIR Melville, NY), p. 243.

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Rosov. N.. Rathgeber. S.. Monkenbusch. M.. "Neutron Spin Echo Spectroscopy at the NIST Center for Neutron Research." in Scattering From Polymers Characterization by X-rays, Neutrons and Light, edited by P. Cebe. B. S. Hsiao, D.J. Lohse, ACS

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Salamat, G., de Uries, R., Kaler, E. W.. Satija, S., Sung, L., "Undulations in Salt-Free Charged Lamellar Phases Detected by Small Angle Neutron Scattering and Neutron

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Sankar, S., Dender, D., Borchers, J. A., Smith, D. J., Erwin, R. W., Kline, S. R.. Berkowitz, A. E., "Magnetic Correlations in Non-Percolated

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Santoro, A., Natali Sora, I., Huang, Q., "Bond Valence Analysis of BaRuO(3)," J. Solid

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Sayer. E. V., Yener, A. K., Joel, E. C, Blackman, M. J., Ozbal, H., "Stable Lead Isotope

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Schmidt, G., Nakatani, A. I.. Butler, P. D., Karim, A., Han, C. C, "Shear Orientation of Viscoelastic Polymer-Clay Solutions Probed by Flow Birefringence and SANS,"

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Schmidt. G., Nakatani, A. I., Butler, P D., Karim. A., Han, C. C, "Shear Orientation of

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Schmidt-Winkel, P., Glinka, C. J., Stucky, G. D., "Microemulsion Templates for Mesoporous Silica," Langmuir 16 (2), 356 (2000).

Schober, H.. Dianoux, A. J.. Cook, J. C, Mezei, F. "Upgrade of the INS Cold Neutron

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Schulz, J. C, Warr, G. G., Butler, P D., Hamilton, W. A., "Adsorbed Layer Structure of

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Shen, C. P, Chacon, L. C, Rosov, N., Elder, S. H., Allman, J. C, Bartlett, N„ "The

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Shirane, G., Gehring P. M., "Soft Phonon Anomalies in Relaxor Ferroelectrics," J. Phys.

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Welp, K. A., Wool, R. P, Agrawal, G., Satija, S. K., Pispas, S., Mays, J., "Direct Observation of Polymer Dynamics: Mobility Comparison Between Central and End

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Wesley, R. D., Cosgrove, T., Thompson, L., "Interactions of Star Polymers With

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Wesley, R. D., Cosgrove, T, Thompson, L., Armes, S. P., Billingham, N. C, Baines, F.

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White, D. C. C, Wu, W. L., Pu. Y, Rafailovich, M., Sokolov, J., "Probe Segregation within an Ultra-Thin Polystyrene Film Studied by X-ray, Neutron Reflectivity and SIMS

and Tg Determination of Polystyrene on a Quartz Substrate by X-ray Reflectivity," Macromol., in press.

Wilemski, G., "Neutron Scattering From Aerosols: Intraparticle Structure Factor, Guinier

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Wirth, B. D., Odette, G. R., Pavinich, W. A.. Lucas, G. E., Spooner, S. E., "Small Angle Neutron Scattering Study of Linde 80 RPV Welds," in Effects ofRadiation on

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70 PUBLICATIONS
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Won. Y. Y. Davis. H. T., Bates, F. S.. Agamalian, M., Wignall, G. D.. "Segment

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Wong-Ng, W., Huang, Q., Lavin, I., Kaduk. J. A., Dillingham. J., Huagan, T.. Suh, J., Cook. L. P.. "Crystal Chemistry and Phase Equilibria of Selected SrO-R,0,-CuO^ and

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Wong-Ng, W.. Kaduk. J. A., Huang. Q.. Roth. R. S.. "Crystal Structure and X-Ray

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Wu. S. Y. Hwang, S. R., Li. W. H., Lee, K. C, Lynn, J. W., Liu, R. S., "Jahn-Teller

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Wu. S. Y, Kuo. C. M.. Wang. H. Y, Li. W. H., Lee, K. C. Lynn. J. W.. Liu. R. S., "Magnetic Structure and Spin Reorientation of the Mn Ions in NdMnO," J. App.

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Wu, W. L.. Lin, E. K., Lin. Q.. Angelopolous, M., "Small-Angle Neutron Scattering Measurements for the Characterization of Lithographically Prepared Structures," in Proceedings ofthe 2000 Intl. Conf. on Characterization and Metrologyfor ULSI

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Wu, W. L., Wallace, W. E.. Lin, E. K., Lynn. G. W., Glinka, C. J.. Ryan, E. T.. Ho.

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Wu. W.. Lin, E. K., Jin, C, Wetzel. J. T. A.. "Three-Phase Model for the Structure of Porous Thin Films Determined by X-ray Reflectivity and Small Angle Neutron

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Wu. W.-L., Lin, E. K., Lin, Q., Angelopolous, M., "Small Angle Neutron Scattering Measurements of Nanoscale Lithographic Features," Science (in press).

Wuensch, B. J., Eberman, K. W., Heremans, C, Ku, E. M., Onnerud, P., Yeo,

E. M., Haile, S. M., Stalick, J. K., Jorgensen, J. D.. "Connection Between OxygenIon Conductivity of Pyrochlore Fuel-Cell Materials and Structural Change with Composition and Temperature," Solid State Ionics 129 (1), 111 (2000).

Wyslouzil, B. E., Wilemski, G., Strey, R., "Aerosol SANS: A New Method to Probe

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Xu. G., Aeppli, G„ Bisher, M. E.. Broholm. C. DiTusa. J. F, Frost, C. D., Ito, T, Oka,

K., Takagi, H., Treacy, M. M. J., "Holes in a Quantum Spin Liquid," Science 289

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Xu, G., Brohohn, C, Reich, D. H., Adams, M. A., "Triplet Waves in Quantum Spin

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Yamaura, K., Huang, Q., Erwin, R.W., Lynn, J. W., Cava, R. J., "A Study of Structure

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Yamaura, K., Huang. Q., Lynn, J. W., Erwin, R. W., Cava, R. J., "Synthesis, Crystal

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Yamaura, K., Huang, Q., Takayama-Muromachi, E., "Crystal Structure and Magnetism of

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Yang, L., Alexandridis, P., " Polyoxyalkylene Block Copolymers in Formamide-Water Mixed Solvents: Micelle Formation and Structure Studied by Small-Angle Neutron

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Yang, L,, Harroun, T. A., Heller, W. T, Weiss, T. M., Huang, H., W., "Supramolecular

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Yang, L., Slawecki, T. M., Alexandridis, P., "Shear Induced Orientation and Structural Transitions in Micellar Cubic Crystals Formed by Solvated Block Copolymers: A

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NIST CENTER FOR NEUTRON RESEARCH 71
INSTRUMENTS AND CONTACTS

High resolution powder diffractometer (BT-1)

J. K. Stalick, (301) 975-6223, judy.stalick@nist.gov

B. H. Toby, (301) 975-4297, brian.toby@nist.gov

DARTS, Residual stress and texture diffractometer (BT-8)

H. J. Prask, (301) 975-6226, hank@nist.gov

P. C. Brand, (301) 975-5072, pbrand@nist.gov 30 m SANS instrument (NG-7)

C. J. Glinka, (301) 975-6242, cglinka@nist.gov

J. B. Barker, (301) 975-6732, barker@nist.gov

J. Sciiuiz, (301) 975-6469, jamie.schulz@nist.gov 30 m SANS instrument (NG-3) (NIST/NSF-CHRNS)

B. Hammouda, (301) 975-3961, hammouda@nist.gov

S. R. Kline, (301) 975-6243, steven.kline@nist.gov

S. Krueger, (301) 975-6734, krueger@nist.gov

8 m SANS instrument (NG-1)

A. Karim, (301) 975-6588, karim@nist.gov

USANS, Perfect crystal SANS (BT-5) (NIST/NSF-CHRNS)

J. B. Barker, (301) 975-6732, barker@nist.gov Cold neutron reflectometer-vertical sample-polarized

beam option (NG-1)

C. F. Majkrzak, (301) 975-5251, cmajkrzak@nist.gov

J. A. Dura, (301) 975-6251, jdura@nist.gov Cold neutron reflectometer-horizontal sample (NG-7)

S. K. Satija, (301) 975-5250, satija@nist.gov

R. Ivkov, (301) 975-4662, rivkov@nist.gov

Triple-axis polarized-beam spectrometer (BT-2)

J. W. Lynn, (301) 975-6246, jeff.lynn@nist.gov

Triple-axis fixed incident energy spectrometer (BT-7)

J. W. Lynn, (301) 975-6246, jeff.lynn@nist.gov

Triple-axis spectrometer (BT-9)

R. W. Erwin, (301) 975-6245, rerwin@nist.gov P M. Gehring, (301) 975-3946, pgehring@nist.gov

SPINS, Spin-polarized triple-axis spectrometer (NG-5)

(NIST/NSF-CHRNS) R M. Gehring, (301) 975-3946, pgehring@nist.gov

S.-H. Lee, (301) 975-4257, seung-hun.lee@nist.gov

FANS, Filter-analyzer neutron spectrometer (BT-4)

T. J. Udovic, (301) 975-6241, udovic@nist.gov R Rapanek, (301) 975-5049, pete@jazz.ncnr.nist.gov

D. A. Neumann, (301) 975-5252, dan@nist.gov

FCS, Fermi-chopper time-of-flight spectrometer (NG-6)

C. M, Brown, (301) 975-5134, craig.brown@nist.gov

T. J. Udovic, (301) 975-6241, udovic@nist.gov

DCS, Disk-chopper time-of-flight spectrometer (NG-4)

J. R. D. Copley, (301) 975-5133, jcopley@nist.gov

J. C. Cook, (301) 975-6403, jeremy.cook@nist.gov

High-flux backscattering spectrometer (NG-2)

R. M. Dimeo, (301) 975-8135, robert.dimeo@nist.gov

Z. Chowdhuri, (301) 975-4404, zema@nist.gov

NSE, Neutron spin echo spectrometer (NG-5)

N. S. Rosov, (301) 975-5254, nrosov@nist.gov

Prompt-gamma neutron activation analysis (NG-7)

R. M. Lindstrom, (301) 975-6281, dick.lindstrom@nist.gov

R. L. Paul, (301) 975-6287, rpaul@nist.gov Other activation analysis facilities

R. R. Greenberg, (301) 975-6285, rgreenberg@nist.gov

Cold neutron depth profiling (NG-0)

G. Lamaze, (301) 975-6202, lamaze@nisLgov

Instrument development station (NG-0)

D. F. R. Mildner, (301) 975-6366, mildner@nist.gov

H. H. Chen-Mayer, (301) 975-3782, chenmayer@nist.gov

Neutron interferometer (NG-7)

M. Arif, (301) 975-6303, muhammad.arif@nist.gov

Fundamental neutron physics station (NG-6)

M. S. Dewey, (301) 975-4843, mdewey@nist.gov

Theory and modelling

N. F. Berk, (301) 975-6224, nfb@nist.gov

T. Yildirim, (301) 975-6228, taner@nist.gov

Sample environment

D. C. Dender, (301) 975-6225, dender@nist.gov

L. J. Santodonato, (301) 975-6657, lsantodonato@nist.gov

72
NIST CENTER

FOR NEUTRON

RESEARCH

For copies of or information on tliis report, contact;

Ronald L. Cappelletti (310) 975-6221

ron.cappelletti@nist.gov

For additional information on the facility, contact:

J. Michael Rowe

(301) 975-6210

mil<e. rowe@nist.gov

John J. Rush

(301) 975-6231

jolin.rush@nist.gov

To obtain guidelines for preparing proposals to conduct research at the facility, contact;

William Kamitakahara

(301) 975-6878

William. l<amitakahara@nist.gov

Location of all contacts:

NIST Center for Neutron Research

Building 235, Room E151, Mail Stop 8562

National Institute of Standards and Technology

Gaithersburg, IVID 20899-8562

Details are also available on the NCNR Web site: www.ncnr.nist.gov.