NIST SP 1168
NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY – NIST CENTER FOR NEUTRON RESEARCH

ON THE COVER

The penetration depth and orientation 

of a single myristoylated GRASP 

protein bound to a lipid membrane as 

determined by neutron reflectometry. See 

the highlight article by Zan et al. on p.12.
2013 ACCOMPLISHMENTS AND OPPORTUNITIES

2013

Accomplishments

and 

Opportunities

NIST Special Publication 1168

Robert M. Dimeo, Director

Steven R. Kline, Editor

December 2013

National Institute of Standards and Technology

Patrick Gallagher, Under Secretary of Commerce 

for Standards and Technology and Director

U.S. Department of Commerce

Penny Pritzker, Secretary
NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY – NIST CENTER FOR NEUTRON RESEARCH

DISCLAIMER

Certain commercial entities, equipment, or materials 

may be identified in this document in order to describe 

an experimental procedure or concept adequately. Such 

identification is not intended to imply recommendation 

or endorsement by the National Institute of Standards and 

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

materials, or equipment are necessarily the best available for 

the purpose.

National Institute of Standards and Technology

Special Publications 1168

Natl. Inst. Stand. Technol. Spec. Publ. 1168, 84 pages

(December 2013)

http://dx.doi.org/10.6028/NIST.SP.1168

CODEN: NSPUE2

U.S. GOVERNMENT PRINTING OFFICEWASHINGTON: 2013

For sale by the Superintendent of Documents,

U.S. Government Printing Office

Internet: bookstore.gpo.gov 

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Washington, DC 20402-0001
2013 ACCOMPLISHMENTS AND OPPORTUNITIES i

TABLE OF CONTENTS

Table of Contents

FOREWORD. . 

THE NIST CENTER FOR NEUTRON RESEARCH. 

NIST CENTER FOR NEUTRON RESEARCH INSTRUMENTS. 

NCNR IMAGES 2013 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

HIGHLIGHTS

ANALYTICAL CHEMISTRY

Analytical applications of delayed neutron activation analysis at the NCNR, K. P. Grogan, et al.. .

BIOLOGY

Sealing biomembranes via bio-mimetic polymers: A structural and dynamics study, 

J. Y. Wang, et al. (CHRNS)  

Direct observation of small reversible clusters in concentrated monoclonal antibody solutions, 

E. J. Yearly, et al. (CHRNS). .

How does the GRASP protein tether the membrane stacks in the Golgi apparatus?, G. -H. Zan, et al. .. .

CHEMICAL PHYSICS

More efficient petroleum refining using a highly hexane-selective Metal-Organic Framework, M. R. Hudson, et al.  .

The role of random electric fields in relaxors, D. Phelan, et al.  .

BH–

4 reorientational dynamics in LiBH4: effects of iodide substitution and nanoconfinement, 

N. Verdal, et al. (CHRNS).. . 

CONDENSED MATTER

Fractionalized excitations in a spin-1/2 kagome lattice antiferromagnet, T. H. Han, et al. (CHRNS).  .

Novel coexistence of half-metallic itinerant ferromagnetism with local-moment antiferromagnetism in 

Ba0.06K0.40Mn2As2, A. Pandey, et al.  .

Phonon-driven superconductivity in the vicinity of ferroelectric and charge density wave (CDW) 

ordering in La(O,F)BiS2, T. Yildirim.  . 

Interfacial ferromagnetism in CaRuO3 / CaMnO3, C. He, et al.  .

Searching for magnetism across the metal-insulator phase transition of a doped 

Jeff = 1/2 Mott insulator, C. Dhital, et al.  .

Frozen spin ice correlations in the ground state of the pyrochlore magnet Tb2Ti2O7, 

K. Fritsch, et al. (CHRNS).  .

ENGINEERING

Stresses in a test artifact produced by additive manufacturing, T. Gnäupel-Herold, et al.. . 

FACILITY DEVELOPMENT

TOF measurements at neutron guide NG-Bu to characterize the source spectrum, J. C. Cook, et al.. .
ii NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY – NIST CENTER FOR NEUTRON RESEARCH TABLE OF CONTENTS

GEOLOGY

Table of Contents

Nano-pore condensation of methane in shales, A. P. R. Eberle, et al.. .

SOFT MATTER

Probing the interlamellar amorphous phase in semicrystalline polyolefins 

using vapor flow, A. G. McDermott, et al. (nSOFT).. .

Fibrillar structure of methylcellulose hydrogels, J. W. McAllister, et al.  .

Polymer chain mobility in confined polystyrene films, B. Akgun, et al.  .

Small-angle neutron scattering reveals the size and shape of bottlebrush 

polymers in solution, S. L. Pesek, et al. (CHRNS).  .

ADVANCES IN MEASUREMENT

A shear cell designed to probe the velocity-velocity gradient (1-2) plane of shear 

in complex fluids, A. K. Gurnon, et al.  .

Rapid and accurate calculation of small-angle scattering profiles using the golden ratio, M. C. Watson, et al.  .

Advances in neutron flux measurement with the Alpha-Gamma device, A. T. Yue, et al.  .

NEUTRON SOURCE OPERATIONS. . 

FACILITY DEVELOPMENT. . 

SERVING THE SCIENCE AND TECHNOLOGY COMMUNITY. . 

THE CENTER FOR HIGH RESOLUTION NEUTRON SCATTERING (CHRNS). . 

2013 AWARDS. .

PUBLICATIONS: AUGUST 1, 2012 TO JULY 31, 2013. . 

INSTRUMENTS AND CONTACTS. .

NIST CENTER FOR NEUTRON RESEARCH CONTACTS. .
2013 ACCOMPLISHMENTS AND OPPORTUNITIES iiiFOREWORD

Foreword

I

am pleased to present this year’s annual report for the NIST Center for Neutron 

Research. This year marked the first full year of reactor operations since the facility 

outage that was completed in 2012. The combination of robust user operations 

and facility developments contributed to a highly productive year. The reactor 

operated for 238 days out of a scheduled 240 days in FY2013. In past years I have 

reported the operational reliability of the cold source. However, in addition to the cold 

source that now serves 12 neutron guides, this year we began operations of the new cold 

source that serves the MACS spectrometer. I am pleased to report that both cold sources 

operated reliably and delivered neutrons 99 % of the scheduled operating time. The long tradition of the reliable 

operations of the reactor source and cold neutron source have been key factors in the scientific productivity 

of the NCNR. In fact, the American Nuclear Society recently recognized the NCNR with the Nuclear Historic 

Landmark Award for the development of the first internationally competitive user facility for cold neutron 

research in the USA.

This was an extremely active year for facility developments. In this year alone the new 10 meter SANS 

instrument was installed and commissioned on a new neutron guide, becoming operational and supporting nSoft 

consortium users. The upgraded MACS instrument was installed on a beamport with its own dedicated cold 

neutron source, commencing user operations and performing as predicted. The new Prompt Gamma Activation 

Analysis instrument was installed on a new neutron guide. The Neutron Spin-Echo instrument is being relocated 

to the guide hall extension where it will be much further away from high magnetic field experiments and can 

operate more robustly. We have taken advantage of this move to improve the neutron polarizer and upgrade the 

power supplies. You can read more details about these facility enhancements in this report.

Finally, the result of our facility operations is in the research carried out by the scientific community. This report 

contains a collection of these research highlights. I invite you to read through the report and see for yourself the 

fascinating work that took place here in the last year. I believe that these highlights speak for themselves.
iv NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY – NIST CENTER FOR NEUTRON RESEARCH

Reactor operator Sam MacDavid is overseeing the wealth of information on the newly upgraded instrumentation console. This upgrade is part of a larger long-term 

project to modernize the entire reactor control room. Real-time telemetry of all of the major systems of the source operation is now available in a unified display, 

providing remote process monitoring and trending capability with no reactor control or safety function. As the result of key Summer Undergraduate Research 

Fellowship (SURF) projects, these trends are also accessible to engineering staff, increasing the ease in viewing and analyzing data. The ability to view trends in 

process values has been invaluable in identifying issues and allowing their repairs before they become an issue.
2013 ACCOMPLISHMENTS AND OPPORTUNITIES 1THE NIST CENTER FOR NEUTRON RESEARCH

The NIST Center for Neutron Research

Neutrons provide a uniquely effective probe of 

the structure and dynamics of materials ranging 

from water moving near the surface of proteins 

to magnetic domains in memory storage 

materials. The properties of neutrons (outlined below) can 

be exploited using a variety of measurement techniques to 

provide information not otherwise available. The positions of 

atomic nuclei in crystals, especially of those of light atoms, 

can be determined precisely. Atomic motion can be directly 

measured and monitored as a function of temperature or 

pressure. Neutrons are especially sensitive to hydrogen, so 

that hydrogen motion can be followed in H-storage materials 

and water flow in fuel cells can be imaged. Residual stresses 

such as those deep within oil pipelines or in highway trusses 

can be mapped. Neutron-based measurements contribute to a 

broad spectrum of activities including engineering, materials 

development, polymer dynamics, chemical technology, 

medicine, and physics.

The NCNR’s neutron source provides the intense, conditioned beams of neutrons required for these types of measurements. In addition to the thermal neutron beams from the 

heavy water or graphite moderators, the NCNR has a large 

area liquid hydrogen moderator, or cold source, that provides 

long wavelength guided neutron beams for the major cold 

neutron facility in the U.S.

There are currently 28 experiment stations: 12 provide high 

neutron flux positions for physics, chemistry, or imaging, and 

16 are beam facilities for neutron scattering research. The 

subsequent pages provide a schematic description of our instruments. More complete descriptions can be found at www.

ncnr.nist.gov/instruments/. The second guide hall is currently 

populated with five instruments, with three new instruments 

under development.

The Center supports important NIST measurement needs, 

but is also operated as a major national user facility with merit-based access made available to the entire U.S. technological 

community. Each year, about 2000 research participants 

from government, industry, and academia from all areas of 

the country are served by the facility (see p. 55). Beam time 

for research to be published in the open literature is without 

cost to the user, but full operating costs are recovered for 

proprietary research. Access is gained mainly through a webbased, peer-reviewed proposal system with user time allotted 

by a beamtime allocation committee twice a year. For details 

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

Foundation and NIST co-fund the Center for High Resolution Neutron Scattering (CHRNS) that operates six of the 

world’s most advanced instruments (see p. 57). Time on 

CHRNS instruments is made available through the proposal 

system. Some access to beam time for collaborative measurements with the NIST science staff can also be arranged on 

other instruments.

WHY NEUTRONS?

Neutrons reveal properties not readily probed by 

photons or electrons. They are electrically neutral and 

therefore easily penetrate ordinary matter. They behave 

like microscopic magnets, propagate as waves, can 

set particles into motion, losing or gaining energy and 

momentum in the process, and they can be absorbed 

with subsequent emission of radiation to uniquely fingerprint chemical elements.

WAVELENGTHS − in practice range from ≈ 0.01 nm 

(thermal) to ≈ 1.5 nm (cold) (1 nm = 10 Å), allowing the 

formation of observable interference patterns when 

scattered from structures as small as atoms to as large 

as biological cells. 

ENERGIES − of millielectronvolts, the same magnitude 

as atomic motions. Exchanges of energy as small 

as nanoelectronvolts and as large as tenths of 

electronvolts can be detected between samples and 

neutrons, allowing motions in folding proteins, melting 

glasses and diffusing hydrogen to be measured. 

SELECTIVITY − in scattering power varies from nucleus 

to nucleus somewhat randomly. Specific isotopes 

can stand out from other isotopes of the same kind 

of atom. Specific light atoms, difficult to observe with 

x-rays, are revealed by neutrons. Hydrogen, especially, 

can be distinguished from chemically equivalent 

deuterium, allowing a variety of powerful contrast 

techniques.

MAGNETISM − makes the neutron sensitive to the 

magnetic moments of both nuclei and electrons, 

allowing the structure and behavior of ordinary and 

exotic magnetic materials to be detailed precisely. 

NEUTRALITY − of the uncharged neutrons allows 

them to penetrate deeply without destroying samples, 

passing through walls that condition a sample’s 

environment, permitting measurements under extreme 

conditions of temperature and pressure. 

CAPTURE − characteristic radiation emanating from 

specific nuclei capturing incident neutrons can be used 

to identify and quantify minute amounts of elements in 

samples as diverse as ancient pottery shards and lake 

water pollutants. 
2 NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY – NIST CENTER FOR NEUTRON RESEARCH

NIST Center for Neutron Research Instruments

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

Scattering (USANS) Diffractometer for microstructure up to 104

 nm.

[2] BT-4 Filter Analyzer Neutron Spectrometer with 

cooled Be/Graphite filter analyzer for chemical 

spectroscopy and thermal triple axis spectrometer.

[3] BT-2 Neutron Imaging Facility for imaging hydrogenous matter in large components such as 

water in fuel cells and lubricants in engines, in 

partnership with General Motors and DOE.

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

incident wavelengths of 0.208 nm, 0.154 nm, and 

0.159 nm, with resolution up to Δ d/d ≅ 8 x 10-4.

[5] BT-9 Multi Axis Crystal Spectrometer (MACS II), a 

cold neutron spectrometer for ultra high sensitivity 

access to dynamic correlations in condensed 

matter on length scales from 0.1 nm to 50 nm and 

energy scales from 2.2 meV to 20 meV.

[6] BT-8 Residual Stress Diffractometer optimized 

for depth profiling of residual stresses in large 

components.

[7] BT-7 Thermal Triple Axis Spectrometer with 

large double focusing monochromator, and 

interchangeable analyzer/detectors systems.

[8] VT-5 Thermal Neutron Capture Prompt Gammaray Activation Analysis Instrument with a 

neutron fluence rate of 3 x 108 cm-2 s-1 used 

for quantitative elemental analysis of bulk 

materials. Generally used for the analysis of highly 

hydrogenous materials (≅ 1 % H) such as foods, 

oils and biological materials.

[9] NG-A Neutron Spin-Echo Spectrometer (NSE) for 

measuring dynamics from 5 ps to 100 ns.

The Center for High Resolution Neutron Scattering (CHRNS) is a partnership between NIST and the National Science Foundation that develops 

and operates neutron scattering instrumentation for use by the scientific 

community. The following instruments are part of the Center: 1 (USANS), 

5 (MACS II), 9 (NSE), 16 (HFBS), 17 (NG-3 SANS), 18 (DCS).

NIST CENTER FOR NEUTRON RESEARCH INSTRUMENT
2013 ACCOMPLISHMENTS AND OPPORTUNITIES 3NIST CENTER FOR NEUTRON RESEARCH INSTRUMENTS

(as of Dec. 2013)

[10] NG-Bl 10 m SANS for macromolecular structure 

measurments. n Soft

[11] NG-D Cold neutron capture Prompt Gamma 

Activation Analysis, for quantitative elemental 

analysis of bulk materials, expecially of 

hydrogenous ones.

[12] NG-D MAGIk off-spectular reflectometer for 

studies of thin-film samples with in-plane 

structure.

[13] NG-D Polarized Beam Reflectometer (PBR) 

for measuring reflectivities as low as 10-8 to 

determine susurface structure.

[14] NG-1 Cold Neutron Depth Profiling for profiling of 

subsurface elemental composition.

[15] NG-1 Detector development station.

[16] NG-2 Backscattering Spectrometer (HFBS) high 

intensity inelastic scattering instrument with 

energy resolution < 1 μeV, for studies of motion in 

molecular and biological systems.

[17] NG-3 30 m SANS for microstructure measurements.

[18] NG-4 Disk Chopper Time-of-Flight Spectrometer 

for diffusive motions and low energy dynamics. 

Wavelengths from ≅ 0.18 nm to 2.0 nm and energy 

resolutions from ≅ 2 μeV to < 10 μeV.

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

(SPINS) using cold neutrons with position 

sensitive detector capability for high-resolution 

studies.

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

accurate techniques for measurement of the 

neutron magnetic dipole moment.

[21-23] NG-6 Neutron Physics Station offering three 

cold neutron beams having wavelengths of 

0.5 nm, 0.9 nm, and “white” for neutron physics 

experiments, including aCORN.

[24] NG-7 30 m SANS for microstructure 

measurements, in partnership with ExxonMobil 

and University of Minnesota’s IPrime.

[25] NG-7 Cold neutron capture Prompt Gamma 

Activation Analysis, for quantitative elemental 

analsis of bulk materials.

[26] NG-7 Neutron Interferometry and Optics Station 

with perfect crystal silicon interferometer. A 

vibration isolation system provides exceptional 

phase stability and fringe visibility.

[27] NG-7 Neutron Physics Interferometry Test Bed for 

developing novel interferometry techniques.

[28] NG-7 Horizontal Sample Reflectometer allows 

reflectivity measurements of free surfaces, liquid/

vapor interfaces, as well as polymer coatings.
4 NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY – NIST CENTER FOR NEUTRON RESEARCH NCNR IMAGES 2013

NCNR Images 2013

Paula Lampen (USF) and Kathryn Krycka (NCNR) test 

out the improvements to polarized SANS at NG7.

Kiyotaka Akabori and Michael Jablin (CMU) are 

ready to make some “MAGIk” happen.

Jiajia Wen (JHU) and Kate Ross measure their 

quantum spin ice at DCS.

Amber Larson (UMd) is ready to collect data at BT1. Aaron Eberle (ExxonMobil) gathers top-secret SANS 

data.

Ryan Murphy (Solvay) and Ron Jones (nSOFT) 

inspect their samples at the 10m-SANS.

NCNR’s William Ratcliff and Charles Brooks 

(Cornell) make some adjustments to their sample 

environment at BT4.

Aman Uddin (U. Conn) and Toshikazu Kotaka 

(Nissan) align a hydrogen fuel cell for neutron 

imaging at BT2.

Joshua Cardiel (UW) carefully loads his surfactant 

samples at USANS.
2013 ACCOMPLISHMENTS AND OPPORTUNITIES 5NCNR IMAGES 2013

Jason Gardner (NSRRC), Tsung Yu Ou Yang and Je Wei Lin (Nat. Taiwan U) and 

Rafael Sa De Freita (Uni. de Sao Paulo) make plans for a DCS experiment.

Summer school students get hands-on experience mounting samples for 

measurement at DCS while NCNR’s Craig Brown supervises.

Summer school students anxiously await the start of their SANS experiment 

under the watchful eye of NCNR’s Matt Wasbrough.

Dan Neumann entertains a tour of undergraduate students from WVU.

Tao Hong (ORNL) prepares for a measurement at 

MACS II.

David Jacobson (NIST) and Greg Hutchings (UDel) 

start a tomography scan of a lithium-air battery at 

the Neutron Imaging Facility.

Dan Phelan (UMN) and NCNR’s Daniel Pajerowski 

change the field on the 10 T magnet during their 

DCS experiment.
6 NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY – NIST CENTER FOR NEUTRON RESEARCH ANALY TICAL CHEMISTRY

Analytical applications of delayed neutron 

activation analysis at the NCNR

K. P. Grogan1, D. J. O’Kelly1, R. M. Lindstrom1, and G. P. Lamaze1

1

National Institute of Standards and Technology, Chemical Sciences Division, Inorganic Chemical Metrology Group, Gaithersburg, MD 20899

Delayed neutron activation analysis (DNAA) is a 

method for measuring fissile elements (e.g., 235U, 

233U, and 239Pu) in materials. This technique 

has been applied to two challenges of national 

need. The first challenge is nuclear forensics. In today’s 

climate, the threat of illicit and clandestine nuclear activities 

has become a major concern for Homeland Security and 

has enhanced the necessity for accurate, sensitive, and rapid 

analytical and forensic techniques to detect and characterize 

nuclear materials. The second challenge is the identification 

and quantification of rare earth elements (REE). REE’s are 

utilized as critical components in a number of industrial 

applications including automobiles, lasers, solid-oxide fuel 

cells, and defense technologies [1]. Several REEs, including 

cerium (Ce), lanthanum (La), and neodymium (Nd), are 

listed as critical or near-critical with regard to the risk for 

supply interruption by the U.S. Department of Energy 2011 

Critical Materials Strategy Summary [2]. The identification 

and measurement of these REEs in new domestic sources is 

an emerging priority. 

When uranium (U) is subjected to a neutron flux and 

fissions, the majority of fission products b-

-decay to stable 

nuclei. A small percentage of fission products, however, 

remain neutron-rich and are known as delayed neutron 

precursors. Delayed neutron precursors will b-

-decay with 

half-lives ranging from less than 1 s to about 1 min. This 

decay occurs with a corresponding delayed neutron emission 

(as compared to the prompt neutrons emitted during the 

original fission reaction). This process is illustrated in 

Fig. 1. A typical DNAA procedure consists of irradiating a 

sample containing fissile elements for approximately 1 min, 

followed by rapid transfer of the sample from the irradiation 

facility to a neutron detection system for a counting time 

of a few minutes. The delayed neutrons emitted from the 

sample are compared to those generated from irradiated 

known standards for quantification of the fissile content in 

the sample. Advantages of DNAA include the potential for 

rapid measurements (5 min or less), non-destructive and 

matrix-independent analyses, and selective and sensitive (subnanogram detection limits for 235U) measurements of fissile 

elements. The DNAA system at the NCNR is one of the 

world’s premier facilities for DNAA measurements. Due to 

the highly thermalized and stable neutron flux from the RT2 

facility at the NBSR reactor, the DNAA system is ideal for 

making rapid and sensitive measurements of U in materials of 

interest for nuclear forensics and for REEs.

FIGURE 1: Process of delayed neutron production. 

The present work describes two applications of DNAA. 

DNAA is first utilized to determine the natural U content in 

two NIST Standard Reference Materials (SRM) 1547 Peach 

Leaves and 1573a Tomato Leaves, which represent potential 

baseline materials for identifying elevated U concentrations 

for nuclear forensics. The second application involves the use 

of instrumental neutron activation analysis (INAA) to 

quantify REEs in NIST SRM 2586 Trace Elements in Soil 

Containing Lead from Paint. Several REEs including Ce, La, 

and Nd are produced as fission products of U during INAA 

and interfere with the measurement of the natural REE 

content of the material [3]. These interferences can be 

corrected by the use of appropriate correction factors based 

on the amount of U present in a sample [3]. Thus, DNAA is 

used in tandem with INAA to quantify the U mass fraction 

in SRM 2586 in order to correct for the REE fission products 

produced during analysis of Ce, La, and Nd.

The DNAA system was calibrated with eight U standards. 

The result of the calibration was a highly linear curve with 

a y-intercept of 1321.8 counts as shown in Fig. 2. Based 

on the intercept of the calibration and a modification of the 

Currie equation [4], the minimum number of detectable 

counts is 1494. This result corresponds to a minimum 

detectable mass of 17 ng natural U (120 pg 235U) when 

compared to the calibration curve.
2013 ACCOMPLISHMENTS AND OPPORTUNITIES 7ANALY TICAL CHEMISTRY

Table 1: INAA Measurements of REEs for SRM 2586.

Element INAA Value (mg/kg) U Correction Factor (Mx/MU) Corrected INAA Value (mg/kg) Reference Value (mg/kg)

Ce 64.98 ± 2.52 0.287 64.35 ± 2.50 58 ± 8

La 29.22 ± 1.14 0.0028 x [e0.85893*T

-1] 28.42 ± 0.98 29.7 ± 4.8

Nd 30.04 ± 3.86 0.21 29.57 ± 3.83 26.4 ± 2.9

FIGURE 2: Uranium standard calibration curve.

Samples of SRM 1547 and SRM 1573a were analyzed by 

DNAA for total U content. The DNAA results for these two 

SRMs are shown in Fig. 3 where the solid lines represent the 

non-certified mass fractions listed on the certificate for each 

material, respectively. The average measured U mass fractions 

were 0.0174 mg/kg ± 0.0006 mg/kg and 0.0412 mg/kg ± 

0.0014 mg/kg for SRM 1547 and SRM 1573a, respectively. 

These values are comparable to the non-certified values (with 

no associated uncertainty value) of 0.015 mg/kg for SRM 

1547 and 0.035 mg/kg for SRM 1573a. These results demonstrate the utility of DNAA for identifying and quantifying 

trace level U mass fractions in environmental samples that 

would be desirable in a nuclear forensics application.

Samples of SRM 2586 were analyzed by DNAA and the 

results are also displayed in Fig. 3. There is no certificate 

value for U in SRM 2586. The average measured U mass 

fraction was 2.20 mg/kg ± 0.06 mg/kg. For validation, SRM 

1632a, Trace Elements in Coal (Bituminous) was analyzed by 

DNAA resulting in an average U mass fraction of 1.27 mg/kg 

± 0.07 mg/kg, which is in agreement with the certified U 

mass fraction of 1.28 mg/kg ± 0.02 mg/kg. These results 

demonstrate the utility of DNAA for measurements of fissile 

elements and provide a U mass fraction that may be used 

to correct for U fission products in the analysis of REEs 

by INAA. The application of this U mass fraction for the 

correction of Ce, La, and Nd mass fractions as determined by 

INAA for samples of SRM 2586 is shown in Table 1. The U 

correction factors were applied by multiplying the measured 

uranium mass fraction by the correction factor (MX/MU). 

The result of this calculation is the apparent measured mass 

fraction of the REE of interest generated from U fission 

during the INAA irradiation. Thus, subtracting this result 

from the initially measured INAA value for each REE gives 

the true value of the REE of interest in the sample prior to 

the generation of fission products. In all cases the measured 

average mass fractions for the REEs are in good agreement 

with certificate values for SRM 2586.

FIGURE 3: Uranium mass fractions in SRM 1547, SRM 1573a, and SRM 2586 as 

measured by DNAA. Lines are the non-certified mass fraction values of U in the 

SRM. There is no certificate value for U in SRM 2586.

The DNAA method provided rapid (5 min per sample) 

analyses with minimal sample preparation and a high degree 

of accuracy and sensitivity. The presented analyses are useful 

for validating the use of DNAA as a tool for nuclear forensics 

and, when coupled with INAA, as a method to more 

accurately measure rare earth elements. Thus, these methods 

have the potential to improve the current state of nuclear 

of forensics and to support the efforts to identify REEs in a 

variety of domestic materials to address the critical supply 

risks that have been projected for the near future. 

References

[1] X. Du, T. E. Graedel, Environ. Sci. Technol. 45, 4096-4101 

(2011).

[2] U.S. Department of Energy. 2011 Critical Materials Strategy 

Summary, (2011).

[3] M. D. Glascock, P. I. Nabelek, D. D. Weinrick, R. M. Coveney, 

Jr., J. Radioanal. Nucl. Chem. 99, 121 (1986).

[4] L. A. Currie, Anal. Chem. 40, 586 (1968).
8 NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY – NIST CENTER FOR NEUTRON RESEARCH BIOLOGY

Sealing biomembranes via bio-mimetic polymers: A 

structural and dynamics study

J.-Y. Wang1, W. Chen2, M. Nagao3,4, J. M. Henderson1, B. A. G. Hammer5, L. He6, B. Akgun3,7, T. Emrick5, 

and K. Y. C. Lee1

1

Department of Chemistry, Institute for Biophysical Dynamics & James Franck Institute, The University of Chicago, Chicago, IL 60637

2

Argonne National Laboratory, Argonne, IL 60439 and Institute for Molecular Engineering, The University of Chicago, Chicago, IL 60637

3

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

4

Indiana University, Bloomington, IN 47408

5

University of Massachusetts, Amherst, MA 01003

6

Oak Ridge National Laboratory, Oak Ridge, TN 37831

7

University of Maryland, College Park, MD 20742

The cell membrane is essentially an integral lipid bilayer 

decorated with membrane proteins and carbohydrates. 

Due to its fragility, traumatic events can disrupt its 

barrier function. While sealing cell membranes is a 

naturally occurring repair process, it can be impeded or too slow 

to cope with the sudden loss of membrane integrity following 

acute injury. Recently, we developed a new membrane-sealing 

polymer [1] containing phosphorylcholine (PC) pendant groups 

that mimic phospholipids, rendering them highly biocompatible 

[2]. When applied to neurons with ischemia-induced injury, this 

polymer shows great promise as a membrane sealant, preventing 

the leakage of intracellular contents and significantly enhancing 

neuronal survival [3]. To fulfill the potential of this family of 

polymers as membrane sealing agents, a thorough understanding 

of the fundamental mechanism responsible for the sealing action 

is thus the key. 

Using neutron reflectivity (NR), small angle neutron scattering 

(SANS) and neutron spin echo (NSE) techniques, we can 

explore polymer-induced alterations in membrane structure and 

dynamics. Fig. 1a shows the NR profile of 1,2-dipalmitoyl

(d62)-sn-glycero-3-phosphocholine-1,1,2,2-d4-N,N,Ntrimethyl-d9 (d75-DPPC) monolayers on D2O at surface pressure 

π = 30 mN/m, and temperature, T = 25 oC. Using a two layer 

model to analyze the data, the best fit suggests the layer thickness 

of the head group and tail to be 6.2 Å and 15.9 Å,

respectively, with their corresponding scattering length 

densities (SLD) to be 6.16 × 10-6 Å-2 and 7.3 × 10-6 Å-2, and an 

interfacial roughness, R, of 3 Å (R is the standard deviation of 

the error function). Adding our biocompatible polymer with 

pendant PC groups [Mw = 27,000 g/mol, where Mw is the 

mass average molecular mass, hereafter denoted as HP_27K] 

to the subphase of a d75-DPPC monolayer under otherwise 

identical experimental conditions gives rise to the NR profile 

shown in Fig. 1b. As the SLD of d75-DPPC is fairly close to 

that of D2O, this contrast matching strategy increases the 

sensitivity of the technique in detecting structural changes if 

the polymer penetrates the lipid film. However, comparison of 

the NR profiles between d75-DPPC and d75-DPPC+HP_27K 

shows little difference, indicating that the polymer has little, 

if any, effect on the structure of the lipid film. It should be 

noted that at π = 30 mN/m and T = 25 oC, DPPC lipids are 

in the condensed phase; this high lipid packing density could 

therefore limit the ability of the PC-polymer to interact with 

the lipids, thus resulting in little change to the NR profile of 

d75- DPPC+HP_27K. 

FIGURE 1: (a) NR profile of d75- DPPC on D2O at  = 30 mN/m and T = 25 C. 

Symbols experimental data; (—) best-fit using two layer model. Inset: scattering 

length density of the best fit to the NR data generated via Motofit. (b) NR profiles 

of d75- DPPC and d75- DPPC+HP_27K on D2O at surface pressure  = 30 mN/m

and T = 25 o

C. Measurements were taken at areas Ad75-DPPC = 47.0 Å2 and 

Ad75-DPPC+HP_27K = 46.0 Å2

. The polymer concentration in the subphase is 100 μmol/L. 

To further explore possible effects of HP_27K on the structure 

of lipid membranes, SANS experiments were performed on 

1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) large 
2013 ACCOMPLISHMENTS AND OPPORTUNITIES 9BIOLOGY

unilamellar vesicles (LUVs) at 37 oC, 25 oC, 23 oC, and 15 oC. 

The main transition temperature, Tm, of DMPC is 23 oC, 

meaning the lipids are in the fluid phase at 37 oC and 25 oC, 

and in the gel phase at 23 oC and 15 oC. SANS data of DMPC 

LUVs at the four temperatures are presented in Fig. 2 (left). 

The scattering from the bilayer is modeled as vesicles with 

a Schulz distribution of radii and composed of three layers, 

each with a corresponding scattering length density. The black 

lines in the figures are the best fits, yielding lipid membrane 

dimensions consistent with the NR results. Upon introducing 

HP_27K (Fig. 2, right) the SANS profiles show little change 

when compared to the pure LUVs, further confirming that 

the polymer, regardless of lipid packing density, has little if 

any qualitative or quantitative influence on the structure of 

lipid membranes. 

FIGURE 2: SANS of DMPC LUVs at 10 mg/mL (left) and DMPC LUVs in the 

presence of 200 μmol/L HP_27K (right) at T = 37 o

C =, 25 oC, 23 oC, and 15 oC. For 

profiles of DMPC in the presence of HP_27K, scattering contribution from the 

polymer was subtracted. The asymmetric three-shell vesicle model was used to 

fit DMPC profiles (black lines).

Considering that HP_27K behaves as a membrane sealant and 

yet imparts little influence on the structure of lipid membranes, 

we hypothesize that the protective effect of the polymer comes 

from its ability to affect membrane undulations. To test this 

hypothesis, NSE measurements were employed to examine 

the dynamics of polymer-induced shape fluctuations of nearly 

spherical DMPC LUVs; analysis of the data allows us to extract 

mechanical constants of the lipid bilayer in the absence or presence of the polymer. Fig. 3 shows the normalized intermediate 

scattering function I(q,t)/I(q,0) originating from the fluctuations 

of lipid membranes in the absence (Fig. 3a), and in the presence 

of 200 μmol/L HP_27K (Fig. 3b), as well as from the polymer 

chains (Fig. 3c) at 37 oC. The I(q,t)/I(q,0) of lipid membranes 

in the presence of HP_27K has a contribution from both lipid 

membranes and polymer chains, which can be expressed as:

where ƒ is the fraction of the contribution from polymer chain 

dynamics in solution. The first term originates from the Zilman 

and Granek model [4] for lipid membranes, which provides the 

bending modulus, κ, of the lipid bilayer, and the second term 

from the Zimm model for polymer chain dynamics in dilute 

solution [5]. As shown in Fig. 3d, κ of DMPC LUVs is found 

to be (12 to 15) kBT at temperatures above Tm and (70 to 80) 

kBT below Tm. With the presence of HP_27K, κ is increased at 

all temperatures. These increases in membrane rigidity suggest 

that HP_27K interacts with lipid membranes through PC-PC 

head groups, and thereby suppresses membrane fluctuations. 

FIGURE 3: Normalized intermediate scattering function for various values 

of q for (a) DMPC LUVs, (b) LUVs in the presence of HP_27K, and (c) HP_27K 

with a polymer concentration of 200 μmol/L, all at 37 o

C. Fits are to the linear 

combination of membrane undulation and polymer dynamics for (a) and (b) and 

polymer dynamics for (c). The bending modulus, κ, as a function of temperature 

for the lipid membrane of (n) DMPC and ( ̈) DMPC in the presence of HP_27K is 

shown in the inset (d).

In summary, this neutron scattering study demonstrates that 

our membrane sealing PC-containing polymer actually has 

little effect on membrane structures, but greatly slows down 

membrane undulations, rigidifying the bilayers. The observed 

influence of the polymer on membrane rigidity only, rather 

than on the membrane static structure, implies that this PCpolymer influences the membrane through weak, non-intrusive 

interactions. The information obtained through these studies, 

in particular NSE, allows us to gain unprecedented insight 

into the intrinsic molecular aspects of these polymers as 

membrane sealants.

References

[1] X. Chen, S. McRae, S. Parelkar, T. Emrick, Bioconjugate 

Chem. 20, 2331 (2009).

[2] S. Monge, B. Canniccioni, A. Graillot, J. Robin, 

Biomacromolecules 12, 1973 (2009).

[3] J.-Y. Wang, W. Chen, K. Y. Lee, et al., manuscript submitted.

[4] A. G. Zilman, R. Granek, Phys. Rev. Lett. 77, 4788 (1996).

[5] E. D. Violette, P. G. DeGennes, Physics 3, 181 (1967). 
10 NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY – NIST CENTER FOR NEUTRON RESEARCH BIOLOGY

Direct observation of small reversible clusters in 

concentrated monoclonal antibody solutions

E. J. Yearly1,2, P. D. Godfrin1,2, T. Perevozchikova1,2, H. Zhang1,3, P. Falus4, L. Porcar4, M. Nagao1,5, J. Curtis1, 

P. Gawande6, R. Taing7, I. E. Zarraga7, N. J. Wagner1, and Y. Liu1,2

1

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

2

University of Delaware, Newark, DE 19716

3

University of Maryland, College Park, MD 20740

4

Institut Laue-Langevin, Grenoble, France

5

Indiana University, Bloomington, IN 47405

6

Theranos Inc., Palo Alto, CA 94304

7

Late Stage Pharmaceutical Development, Genentech Inc, South San Francisco, CA 94080

Therapeutic monoclonal antibodies (mAb) have 

been found to be highly effective agents in the 

treatment of immunological and allergic disorders 

as well as malignant growths with a high level of 

success due to their structure specificity and low toxicity in 

contrast to many traditional small molecule drug options. 

During the last several decades, over 20 mAbs have been 

approved by the Food and Drug Administration for clinical 

use and several hundred are currently in development. 

Because of their success and effectiveness, mAbs are one of 

the fastest growing therapeutic agents on the market. 

The importance of mAb-based drugs motivates fundamental 

research into problems related to their manufacture and ease 

of clinical uses. In particular, the pharmaceutical industry 

is proposing to use subcutaneous injection (SC) delivery 

methods for some mAbs for convenience and reduced 

number/frequency of administrations. A high concentration 

of mAbs (> 100 mg/mL) is often required to attain the 

effective dosage, which sometimes is associated with an 

undesired large solution viscosity. Though there is no 

industrial standard for the upper limit of the viscosity where 

SC is feasible, it is widely believed that the solution viscosity 

should be below 50 mPa s. However, the viscosity of many 

mAb proteins at high concentrations is much higher than 

this value. The formation of reversible/dissociable clusters at 

relatively high protein concentrations has been hypothesized 

to cause the high viscosities observed for some mAb solutions. 

One important characteristic of reversible clusters is that the 

clusters form at high concentration and reversibly dissociate 

into monomers at sufficiently low concentrations. However, 

to date, it has been difficult to directly observe these mAb 

dynamic clusters and quantitatively characterize their 

microstructure in crowded environments. Here, we combine 

the methods of small-angle neutron/x-ray scattering (SANS/

SAXS), neutron spin echo (NSE), and computer simulations 

to conclusively identify the formation of dynamic clusters and 

their morphology in highly concentrated and viscous mAb 

solutions [1,2]. In particular, NSE allows the estimation of 

the hydrodynamic radius and characterization of the dynamic 

properties in concentrated solutions.

Two mAbs with markedly different solution viscosities, 

denoted as mAb1 and mAb2, are used as model systems. Both 

mAbs have been widely investigated. They are constructed 

with the same human IgG1 framework, and thus, have nearly 

the same molecular mass (≈ 150 kDa ) and primary sequence, 

with differences only in the complementarity determining 

region. Lyophilized forms of these mAbs are reconstituted 

into D2O-based buffers to reduce the incoherent background 

during neutron scattering experiments. Both mAbs have a 

positive net charge, +17 for mAb1 and +27 for mAb2. The 

reconstituted protein solutions have the ionic strength of the 

solvent of ≈ 17 mmol/L. Fig. 1 shows the solution viscosity, 

η, for these mAbs as a function of concentration, C, at 25  ̊C. 

Note that η of mAb1 has an anomalously large viscosity of 

310 mPa s at 150 mg/mL compared to many other mAbs 

that have much lower viscosity. For example, η for mAb2 

is only 18 mPa s at 150 mg/mL. Even though the η of 

mAb1 does not seem unusually high compared with many 

other materials such as polymer blends or colloidal glass/gel 

systems, this viscosity limits the allowable concentration for 

bulk manufacturing as well as delivery through thin needles. 

The low concentration mAb solutions are first analyzed by 

SAXS and DLS. The combined analyses of the apparent 

radius of gyration and the apparent hydrodynamic radius 

demonstrate that at 1 mg/mL, both mAb1 and mAb2 exist as 

only monomers. However, when the concentration increases 

to about 10 mg/mL, the mAb1 solution is dominated by 

clusters while mAb2 exists still as monomers. The average 

molecular mass of mAb1 clusters at 10 mg/mL is estimated to 

be about that of a dimer. It should be noted that this cluster 

formation in mAb1 solutions is fully reversible upon dilution. 

Therefore, the microstructure of mAb1 in solution progresses 

from dispersed monomers to an increasing proportion of 
2013 ACCOMPLISHMENTS AND OPPORTUNITIES 11BIOLOGY

reversible clusters as concentration increases from 1 mg/mL to 

10 mg/mL. However, at higher concentrations ( > 10 mg/mL), 

it is very difficult to accurately determine the evolution of 

clusters using DLS or SANS/SAXS due to the effect of the 

inter-particle structure factor and collective diffusion.

η (mPa s)

400

mAb1

mAb2

300

200

100

0

0 50 100 150

C (mg/mL)

FIGURE 1: The viscosity of mAb1 and mAb2 as a function of concentration. 

The inset represents a cluster of mAb1 that is responsible for the increased 

viscosity.

To extract a more quantitatively accurate cluster size in the 

highly concentrated protein solutions, we use NSE and 

measure the short-time self-diffusion coefficient, Ds, of 

proteins in solution, which is related to the hydrodynamic 

radius of the clusters. NSE measures the normalized 

intermediate scattering function, S(Q,t)/S(Q), which can 

be expressed as e 

–D c(Q)Q 

2

t in the short-time limit, where 

Dc(Q) is the short-time collective diffusion coefficient 

with the asymptotic value in the high Q limit being the 

short-time self-diffusion coefficient, Ds, through which the 

apparent hydrodynamic radius can be estimated [3]. Because 

Rh ~ 1/Ds, the ratio of 1/Ds between mAb1 and mAb2 is 

an estimate of the average size of the dynamic clusters in 

mAb1 solutions relative to mAb2. It has been shown that 

mAb2 remains dispersed as monomers through the studied 

concentration range [1]. Thus this ratio is an indicator of 

the relative size of reversible clusters in mAb1 solutions. 

Fig. 2 shows the ratio of 1/Ds between mAb1 and mAb2 as a 

function of C. Note that when C ≤ 10 mg/mL (star symbols 

in Fig. 2), Ds is approximated with the results obtained by 

DLS while at higher concentrations, Ds is obtained by NSE. 

At 1 mg/mL, the ratio is one, as both mAb1 and mAb2 exist 

as monomers in solutions. At 10 mg/mL, the ratio reaches 

about 1.7. It is intriguing to observe that this ratio does not 

change substantially with further increases in concentration 

up to 150 mg/mL. This suggests that mAb1 protein clusters 

form at relatively low concentrations, and their size remains 

relatively constant up to high concentrations. This behavior 

is akin to that of self-assembled micellization in surfactant 

solutions, where above a critical micelle concentration, 

additional surfactant added to the system goes into micelle 

formation. The NSE diffusivity results here suggest the critical

monomer concentration for mAb1 is around 10 mg/mL.

Therefore, at high concentrations, such as 150 mg/mL, 

the dominating fraction of mAb1 species is the small 

reversible clusters. Therefore, the formation of small clusters 

is the driving force for the large viscosity in our samples.

1.6

1.2

Ratio 0.8

0.4

monomeric state cluster state

0

0 50 100 150

C (mg/mL)

FIGURE 2: The ratio of the self-diffusion coefficient between mAb2 and mAb1 

as determined from DLS (black) and NSE (red). The ratio is the relative cluster 

size of mAb1 compared to mAb2.

In conclusion, using NSE to measure diffusivity and SANS 

to probe the microstructure of two model mAb proteins in 

solution over a broad concentration range, we demonstrate 

that the formation of a large fraction of reversible clusters in 

solution substantially increases the viscosity of mAb solutions. 

The average cluster size remains almost identical over a wide 

range of concentrations. The insights obtained here on mAb 

clustering behavior and its impact on bulk properties such 

as viscosity are useful in the development of mAbs and their 

formulations with desired solution properties. These in turn 

aid in their efficient production and their effective delivery in 

the clinic.

References

[1] E. J. Yearley, I. E. Zarraga, S. J. Shire, T. M. Scherer, Y. Gokarn, 

N. J. Wagner, Y. Liu, Biophys. J. 105 (30) 720 (2013).

[2] E. J. Yearley, P. D. Godfrin, T. Perevozchikova, H. Zhang, 

P. Falus, L. Porcar, M. Nagao, J. Curtis, P. Gawande, R. Taing, 

I. E. Zarraga, N. J. Wagner, Y. Liu, submitted, (2013).

[3] Y. Liu, L. Porcar, J. Chen, W.-R. Chen, P. Falus, A. Faraone, 

E. Fratini, K. Hong, P. Baglioni, J. Phys. Chem. B 115, 

7238 (2011).
12 NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY – NIST CENTER FOR NEUTRON RESEARCH BIOLOGY

How does the GRASP protein tether the membrane 

stacks in the Golgi apparatus?

G. H. Zan1, C. Bachert2, F. Heinrich1,4, M. Lösche1,3,4, and A. D. Linstedt2

1

Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213

2

Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213

3

Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213

4

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

I

n the Golgi apparatus of a mammalian cell, freshly 

synthesized proteins are modified, sorted, and packaged 

for shipping to destinations within or outside the cell. 

The large Golgi apparatus can be easily recognized 

under a light microscope by its elongated, ribbon-like 

membrane network. Golgi membranes form stacks of 

sub-compartments, called cisternae, in which the various 

functions of the Golgi are performed. A membrane protein 

family, suitably named GRASP, tethers these stacks of 

membranes giving the Golgi structural integrity. With 

neutron scattering methods available at the NIST Center 

for Neutron Research our collaboration investigated the 

structural basis for membrane tethering by the GRASP 

protein.

Golgi cisternae are either linked by self-associating GRASP55 

or GRASP65 proteins [1,2]. At each tether point two 

GRASP molecules that are located on adjacent membrane 

surfaces form one structural unit, or homo-dimer. Each 

GRASP protein contains two PDZ-like domains and an 

internal PDZ ligand that protrudes from the surface of 

the molecule. PDZ domains are globular protein-protein 

interaction modules found in a large number of proteins. 

Self-association of GRASP occurs via the intermolecular 

insertion of the ligand into the binding groove of the first 

PDZ domain. The GRASP proteins are anchored to their 

respective Golgi cisternae by a combination of an N-terminal 

myristic acid and interaction with a Golgi-localized binding 

partner. In the case of GRASP65, this binding partner is 

GM130, which contains a C-terminal PDZ ligand that 

binds the second PDZ domain. Such dual anchoring of 

the GRASP appears to be required not only for its stable 

membrane association but also for its membrane tethering 

activity. Stable, singly anchored versions of GRASP proteins 

have been created using transmembrane domains but these 

fail to tether, whereas similar dually anchored constructs 

retain full activity. Immuno-precipitation of these constructs 

suggests that the function of dual anchoring is to prevent cis 

interactions within the same membrane that might interfere 

with the tethering function. These observations, together 

with the relative positions of the internal ligand and the PDZ 

binding groove on the surface of the molecule, suggest that 

orientation on the membrane may be the mechanism that 

favors GRASP interactions in trans relative to those in cis. 

Orientation-dependent control could have broad implications 

towards understanding the many important membrane crossbridging interactions. 

For our studies we prepared GRASP55 in either its 

myristoylated or non-myristoylated form. Both forms 

contain a C-terminal hexa-histidine tag that binds to 

N-nitrilotriacetic acid (NTA)-functionalized lipids in the 

bilayer, mimicking the Golgi-localized binding partner of 

GRASP55. With a functional assay we showed that the dually 

anchored form retains tethering activity, while the singly 

anchored form does not. With neutron reflectometry, we 

directly determined the orientations of the singly and dually 

anchored proteins at the membrane. As lipid membrane 

mimics, sparsely tethered bilayer lipid membranes [3] were 

used. Here, the tether molecules that anchor the membrane 

to the solid support create a nanometer-thick hydrated layer 

between the solid surface and the lipid bilayer that keeps the 

bilayer in the physiologically relevant in-plane fluid state, 

while allowing neutron scattering analysis of the associated 

proteins [4,5]. Fig. 1 shows the measured reflectivity for the 

myristoylated GRASP55. 

The structural envelope of the membrane-associated GRASP 

domain was modeled using a free-form spline, and by means 

of rigid body rotations of the GRASP crystal structure [7] 

(see Fig. 2, for the myristoylated GRASP 55). Both modeling 

approaches are in agreement with each other, and show a 

clear dependence of the protein orientation on myristoylation. 

Whereas the envelope of the non-myristoylated GRASP is 

compatible with several orientations, all of them present both 

PDZ domains to the membrane. On the other hand, the data 
2013 ACCOMPLISHMENTS AND OPPORTUNITIES 13BIOLOGY

FIGURE 1: Neutron reflectometry curves with best fit, and scattering length 

density profile of the entire sample with and without GRASP protein bound 

to the lipid membrane. Only reflectivity measurements taken with D2O-based 

bulk solvent are shown. The scattering length density profile was determined 

using a co-refinement of all measured reflectivity curves in D2O and H2O-based 

buffer and a composition-space model [6]. Error bars on the data represent one 

standard deviation.

for the myristoylated version could be fit only with a single 

orientation (see Fig. 3). There, the protein assumes an upright 

orientation in which only one PDZ domain interfaces with 

the membrane and presents the myristoyl group to the 

membrane interface. 

FIGURE 2: Composition-space model [6] for the lipid bilayer and the envelope 

of the bound myristoylated GRASP protein. The protein envelope was 

determined using a free-form spline model. Uncertainties were calculated 

using a Monte Carlo Markov Chain method [8]. For comparison, the protein 

envelope shown is from the best-fit orientation of the x-ray solution structure 

of GRASP after reintroducing residues that were not crystallized.

FIGURE 3: The penetration depth and orientation of a single myristoylated 

GRASP protein bound to a lipid membrane as determined by neutron 

reflectometry.

The presented work provides direct evidence that protein 

orientation on the membrane depends critically on protein 

myristoylation, thus giving a structural explanation to the 

experimental observation that dual anchoring is required for 

membrane tethering of GRASP [9]. Based on the protein 

orientation found from neutron reflectometry, molecular 

modeling will be used to construct a model of the trans 

tethering complex to help understand and visualize the 

tethering process.

References

[1] J. Shorter, R. Watson, M. E. Giannakou, M. Clarke, G. 

Warren, F. A. Barr, EMBO J. 18, 4949 (1999).

[2] F. A. Barr, M. Puype, J. Vandekerckhove, G. Warren, Cell 91, 

253 (1997).

[3] D. J. McGillivray, G. Valincius, D. J. Vanderah, W. Febo-Ayala, 

J. T. Woodward, F. Heinrich, J. J. Kasianowicz, M. Lösche, 

Biointerphases 2, 21 (2007).

[4] H. Nanda, S. A. K. Datta, F. Heinrich, M. Lösche, A. Rein, S. 

Krueger, J. E. Curtis, Biophys. J. 99, 2516 (2010).

[5] S. Shenoy, P. Shekhar, F. Heinrich, M. C. Daou, A. Gericke, A. 

H. Ross, M. Lösche, PLoS ONE 7, e32591 (2012).

[6] P. Shekhar, H. Nanda, M. Lösche, F. Heinrich, J. Appl. Phys. 

110, 102216 (2011).

[7] S. T. Truschel, D. Sengupta, A. Foote, A. Heroux, M. R. 

Macbeth, A. D. Linstedt, J. Biol. Chem. 286, 20125 (2011).

[8] B. J. Kirby, P. A. Kienzle, B. B. Maranville, N. F. Berk, J. 

Krycka, F. Heinrich, C. F. Majkrzak, Curr. Opinion Coll. 

Interface Sci. 17, 44 (2012).

[9] H. -Z. Goh, C. Bachert, F. Heinrich, H. Nanda, M. Lösche, A. 

D. Linstedt, J. Biol. Chem. (in preparation).
14 NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY – NIST CENTER FOR NEUTRON RESEARCH CHEMICAL PHYSICS

More efficient petroleum refining using a highly 

hexane-selective Metal-Organic Framework

M. R. Hudson1, C. M. Brown1,2, Z. R. Herm3, B. M. Weirs

3

, J. A. Mason3, J. M. van Baten4, P. Zajdel

5

, 

N. Masciocchi

6

, R. Krishna 4, and J. R. Long 3

1

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

2

University of Delaware, Newark, DE 19716

3

University of California, Berkeley, CA 94720

4

Van’t Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, Netherlands

5

Institute of Physics, University of Silesia, ul. Uniwersytecka 4, 40-007 Katowice, Poland

6

Dipartimento di Scienza e Alta Tecnologia, Università dell’Insubria, via Valleggio 11, I-22100 Como, Italy

Metal-organic frameworks (MOFs) constitute a 

large family of microporous solids exhibiting 

high surface areas, tunable pore dimensions, and 

adjustable surface functionality. The possibility 

of creating pore characteristics in MOFs that cannot readily 

be achieved in zeolites or carbons expands the opportunities 

for molecular recognition [1]. The efficient separation 

of alkane isomers by adsorption is especially challenging 

because the molecules are chemically inert and have similar 

polarizabilities, leaving shape as the method of differentiation. 

This separation is critical to the production of gasoline, which 

includes ≈ 10 % pentanes and hexanes. We have recently [2] 

reported a MOF whose structure and n-hexane adsorption 

properties were characterized with neutron diffraction, and 

features sharply angled pore walls capable of fractionating 

alkane isomers according to the degree of branching. 

Hexanes of formula C6H14 are generated at enormous scale 

through a catalytic isomerization reaction that results in a 

thermodynamically controlled product stream composed of 

(10 to 30) % mole fraction of each of the 5 possible isomers. 

The value of a particular isomer as a component in the 

gasoline pool is related to its research octane number (RON) 

and is highest for the dibranched hexanes 2,3-dimethylbutane 

(2,3-DMB) and 2,2-dimethylbutane (2,2-DMB), which have 

values of 105 and 94, respectively. The RONs for the 

monobranched isomers 2-methylpentane (2-MP) and 

3-methylpentane (3-MP) are substantially lower, at 74 and 

75, respectively, while the value for linear n-hexane is only 

30. To achieve higher octane number blends, current 

processes sieve n-hexane by using zeolites, generating a 

mixture of the other four isomers with a final RON of nearly 

83 while returning n-hexane to the isomerization reactor. 

Some separation processes achieve higher-grade mixtures by 

subsequently distilling the monobranched isomers away 

from the valuable DMB products. An improved hexaneseparation process would selectively isolate the most valuable 

products, 2,3-DMB and 2,2-DMB, while returning the less 

valuable monobranched isomers to the isomerization reactor 

along with n-hexane (Fig. 1). It would potentially benefit 

public health, because it could reduce the usage of toxic 

aromatics, which are currently added to boost the octane 

number of gasoline. 

FIGURE 1: Proposed hexane isomer separation processes including the 

research octane numbers and final product RON. Fe2(BDP)3 may make it viable 

to isolate only the two most valuable isomers. 

In comparing the structures of zeolites to those possible in 

MOFs, a prominent distinction lies in the angles that can 

be obtained for the internal pore walls. Whereas the pore 

contours defined by a zeolite scaffolding are necessarily 

obtuse, the higher coordination numbers possible for the 

metal nodes within a MOF can give rise to flat pore surfaces 

that intersect at acute angles. This is apparent in the structure 

of the new MOF Fe2(BDP)3 (Fig. 2). The rigid, nearly planar 

1,4-benzenedipyrazole anionic ligands define a channel 

structure featuring sharply angled crevices running along the 

triangle corners with chains of octahedral iron(III) centers 

forming the vertices of the triangles. The strong iron(III)-

pyrazolate bonds and highly connected architecture of 

Fe2(BDP)3 lend it exceptional chemical and thermal stability. 

The material can be boiled in aqueous solutions at pH = 2 

to pH = 10 for 2 weeks or heated in air to at least 280 °C 

without losing crystallinity. Pure-component equilibrium 

adsorption isotherms for the 5 different hexane isomers were 

measured for Fe2(BDP)3 at 3 temperatures within the range 

relevant to the industrial separation. In contrast to zeolite 

5A, a sieve for n-hexane, the dimensions of the channels 

in the evacuated structure of Fe2(BDP)3 are large enough 

to accommodate all 5 hexane isomers. At 100 mbar and 

200 °C, Fe2(BDP)3 adsorbs 60 % more n-hexane by volume 

and 100 % more by mass than zeolite 5A. This enhancement 

renders Fe2(BDP)3 a more efficient adsorbent than zeolite 5A 

for the n-hexane separation presently carried out in industry. 

Complementary to the ordered adsorption of dibranched 

isomers, neutron diffraction data demonstrate the lack of 

a preferred arrangement of n-hexane molecules within the 
2013 ACCOMPLISHMENTS AND OPPORTUNITIES 15CHEMICAL PHYSICS

pores of Fe2(BDP)3 when dosed with perdeuterated n-hexane. 

Attempts to refine the position of the n-hexane molecules 

in both samples were thoroughly exhausted by using several 

different refinement approaches, suggesting that there is 

unlikely any correlation between the positions of guests 

adsorbed in each pore.

FIGURE 2: (A) H2BDP ligand; (B) the [001] direction in Fe2(BDP)3 structure, 

(Fe- orange, N- blue, and C- gray with H omitted); (C) chains of pyrazolatebridged FeIII octahedra; (D/E) van der Waals surfaces with snapshots of  

hexane isomers from simulations.

In addition to entropic differences, the enthalpies of 

adsorption among the 5 hexane isomers in Fe2(BDP)3 are 

dependent on the degree of branching as well. Isosteric 

heats of adsorption were calculated by differentiation of the 

temperature-independent fits to the isotherm data (Fig. 3). 

The linear n-hexane isomer has the strongest interaction with 

the framework, because a greater fraction of its surface can 

interact with the triangular channel pore surface than the 

other isomers, while the more compact DMB isomers are 

not flexible enough to maximize van der Waals interactions 

with the pore surfaces and have the lowest enthalpies at 

all loadings. The isomers are all interacting with the same, 

relatively homogeneous surface differently. This trend has 

also been observed in other MOFs for a selected subset of 

hexane isomers but never for all 5 isomers. The trends in 

the enthalpy and entropy of adsorption for the 5 hexane 

isomers conspire to generate a free energy hierarchy of 

linear < monobranched < dibranched isomer adsorption. 

Although separate enthalpy and entropy trends of this type 

have been established previously, the combined contributions 

of both within Fe2(BDP)3 offers exceptional potential for 

separating the valuable dibranched hexanes from the other 

isomers. The hexane isomer separation ability of Fe2(BDP)3

was evaluated with a breakthrough experiment in which an 

equimolar mixture of all 5 isomers in N2 was passed over 

a bed of the material heated at 160 °C (Fig. 3). Pure 2,2-

DMB eluted first, followed by 2,3-DMB, those with high 

RON values, then 2-MP eluted subsequently, immediately 

followed by 3-MP and finally, much later, n-hexane. During 

the beginning of the experiment, the RON of the eluted 

mixture rises to greater than 90, significantly higher than 

the value of 83 that is typical for industrially refined hexane 

blends. The shape of the breakthrough curve for each isomer 

is informative with regard to the separation. The steepness of 

the DMB breakthrough events suggests that the separations 

for these isomers result from essentially equilibrium processes 

and are not diffusion controlled. The two MPs and n-hexane 

display more gradual breakthrough events, suggesting that 

diffusion is a contributory factor in the elution dynamics.

FIGURE 3: (A) Isosteric heats of adsorption vs. hexane loading; (B)

Experimental breakthrough data with calculated RON for 5 hexanes eluting 

through Fe2(BDP)3 at 160°C.

Pulse chromatography simulations were performed to further 

probe the separation properties and indicate that the material 

can separate a mixture of hexane isomers into three fractions: 

2 DMB isomers, 2 MP isomers, and n-hexane. These 3 

fractions could potentially serve independent purposes: 

the DMB added to gasoline, the n-hexane reintroduced 

to the isomerization reactor, and the MP isomers returned 

to the isomerization reactor downstream, allowing for 

better conversion. Such a staged recycling scheme could 

significantly boost the efficiency of the isomerization process. 

A relevant comparison is obtained by comparing the number 

of moles of 92 RON product that can be obtained per liter 

of adsorbent in a packed bed adsorber from published data 

and Configurational-bias Monte Carlo (CBMC) simulations. 

These comparisons show that for Fe2(BDP)3 the 92 RON 

productivity is 0.54 mol/L, whereas the values obtained 

for other adsorbents are consistently lower. Our CBMC 

calculations suggest that the size of the channels in Fe2(BDP)3

is nearly optimal for hexane separation. Narrower triangular 

channels cannot accommodate all 5 isomers, whereas wider 

channels do not maximize the differences in van der Waals 

contacts. 

We have determined that the adsorption selectivity and 

structural stability of Fe2(BDP)3 may make it viable to isolate 

only the two most valuable isomers from the other three 

leading the way to cheaper, more energy efficient gasoline 

production in the future.

References

[1] E. D. Bloch, W. L. Queen, R. Krishna, J. M. Zadrozny, C. M. 

Brown, J. R. Long, Science 335, 1606 (2012).

[2] Z. R. Herm, B. M. Weirs, J. A. Mason, J. M. van Baten, M. R. 

Hudson, P. Zajdel, C. M. Brown, N. Masciocchi, R. Krishna, 

and J. R. Long, Science 340, 960 (2013).
16 NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY – NIST CENTER FOR NEUTRON RESEARCH CHEMICAL PHYSICS

The role of random electric fields in relaxors

D. Phelan1, C. Stock2, J. A. Rodriguez-Rivera1,3, J. Leao1, S. Chi1,3, X. Long4, Y. Xie4, A. A. Bokov4, Z.-G. Ye4, 

P. Ganesh5, and P. M. Gehring1

1

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

2

University of Edinburgh, Edinburgh EH9 3JZ, UK

3

University of Maryland, College Park, MD 20742

4

Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada

5

Oak Ridge National Laboratory, Oak Ridge, TN 37831

The remarkable electromechanical properties 

of lead-oxide, perovskite PbBO3 relaxors such 

as Pb(Mg1/3Nb2/3)1-x TixO3 (PMN-xPT) and 

Pb(Zn1/3Nb2/3)1-xTixO3 (PZN-xPT) have inspired 

numerous attempts to understand the piezoelectricity in terms 

of the structural phase diagram. The diagram contains a steep 

morphotropic phase boundary (MPB) separating pseudorhombohedral and tetragonal states over a narrow compositional 

range where the piezoelectricity is maximal. These materials 

exhibit very low hysteresis, extremely large dielectric constants, 

and record-setting piezoelectric coefficients at room temperature 

that form an unusually appealing set of properties. These 

have the potential to revolutionize a myriad of important 

technological applications spanning medical diagnostic 

sonography, military sonar, energy harvesting, and highprecision actuators. Many researchers have argued that quenched 

random electric fields (REFs) play a central role in establishing 

the relaxor phase, in part because the B-sites of all known leadoxide perovskite relaxors are occupied by random mixtures of 

heterovalent cations. However recent theoretical work suggests 

relaxor behavior can occur in the absence of REFs [1,2]. In fact, 

it has not been proven that REFs are essential to the relaxor state 

or if they play any role in the ultrahigh piezoelectricity. These 

basic questions persist in the face of decades of research because 

no rigorous definition of a relaxor exits, i.e., there is no precise 

mathematical formulation of the relaxor order parameter. To 

date any material for which the real component of the dielectric 

permittivity εʹ(ω,T ) exhibits a broad peak at a temperature 

Tmax that depends strongly (and in some cases only weakly) on 

the measuring frequency is classified as a relaxor. This definition 

has been applied equally to PMN and PZN, which possess 

strong REFs, as well as to specific compositions of 

K(Ta1-xNbx)O3 (KTN), (K1-xLix)TiO3 (KLT), Ba(Zr1-xTix)O3

(BZT), and Ba(Sn1-xTix)O3 (BST), all of which possess 

comparatively weak REFs.

To identify REF-specific properties uniquely one must compare 

identical systems that differ only in the strength of the REFs. 

While such an idealized situation does not exist, the recent 

breakthrough in the growth of millimeter-size, high-quality, 

single crystals of Pb(Zr1-xTix)O3 (PZT) has finally provided 

experimentalists with a nearly perfect model system with which 

such a comparison can be made to classic relaxor systems such as 

PMN-xPT. Both PZT and PMN-xPT are disordered, lead-oxide 

perovskites, and both exhibit phase diagrams as a function of Ti 

composition that contain an MPB near which exceedingly large 

piezoelectric coefficients are observed. Moreover, both materials 

possess nearly identical average B-site ionic radii; the average 

B-site ionic radius of PMN is equal to that of PZT with an 

atomic fraction of 46 % Ti. But whereas PMN possesses strong 

REFs, PZT is composed of homovalent Zr4+ and Ti4+ B-site 

cations and thus is representative of the weak REF limit.

Fig. 1(a) shows the temperature and frequency dependence of 

the real part of the dielectric permittivity of PMN. From 102 Hz 

to 105 Hz the peak permittivity shifts to higher temperature 

by 18 K; this behavior is the hallmark of all relaxors [3]. The 

same measurement made over the same frequency range on 

a single crystal specimen of PZT with x = 0.325 is shown in 

Fig. 1b, and no shift in temperature is evident. This dielectric 

response is consistent with that of a conventional ferroelectric 

phase transition near 600 K and shows that, despite the many 

similarities between PZT and PMN, PZT is not a relaxor. 

It is also consistent with the theoretical work of Grinberg 

et al. who used density functional theory to parameterize a 

phenomenological Landau model of the dielectric frequency 

dispersion. The parameters are the average B-site cation 

displacement from the high-symmetry cubic structure, DB, 

and the second moment of the valence of the two B-site-cation 

nearest neighbors of each oxygen atom, <V 2 >, which is a 

measure of the REF strength [2]. Using only these two input 

parameters, Grinberg et al. obtain quantitative agreement with 

all lead-based, perovskite relaxor systems for which both the 

local cation order and dielectric response have been measured. 

Interestingly, their model permits a frequency-dependent 

dielectric response even for materials where <V 2 > = 0 (i.e., 

for vanishingly small REF strength) provided that the average 

B-site cation displacement is not too large DB < 0.11 Å). In 

the case of PZT there is no frequency dependence, because 

DB is large enough to stabilize long-range ferroelectric order. 

But there exist other disordered perovskite materials composed 

of homovalent B-site cations for which <V 2 > = 0 and DB is 

small that do exhibit a strongly frequency-dependent dielectric 

response. Examples include compositions of BZT with 

0.25 < x < 0.42 and BST with 0.20 < x < 0.50, which retain 

an average cubic symmetry at all temperatures studied. The 

fundamental questions are then: (1) are REFs essential to the 

relaxor phase observed in the lead oxides, (2) what is the relaxor 
2013 ACCOMPLISHMENTS AND OPPORTUNITIES 17CHEMICAL PHYSICS

order parameter, and (3) do REFs play a role in the ultrahigh 

piezoelectric response?

FIGURE 1: Temperature dependence of the real part of the dielectric 

permittivity measured along [001] for (a) PMN and (b) PZT (x = 0.325) at various 

frequencies. Neutron elastic diffuse scattering intensity measured at 1.7 K 

along [110] in the (HHL) scattering plane for (c) PMN and (d) PZT. The insets to 

(c) and (d) illustrate the shape of constant elastic-scattering-intensity contours 

measured near (001) in the (HHL) scattering plane for the same PMN and PZT 

crystals at, respectively, 300 K and 10 K, and are plotted on a log-intensity scale.

We examined the neutron diffuse scattering from single crystals 

of PZT and PMN under exactly the same conditions to study 

the influence of REFs on the nanometer-scale structure of 

lead-oxide perovskite relaxors. To account precisely for the differences in crystal size and beam illumination, the diffuse scattering data from both crystals were normalized by the integrated 

intensity of a transverse acoustic (TA) phonon also measured 

under identical conditions. The data in Fig. 1(d) shows that the 

diffuse scattering for the non-relaxor PZT is at least a factor of 

20 weaker than that in PMN. The inset in panel (d) shows a logscale intensity map of the elastic scattering from the same PZT 

crystal at 10 K in the same (HHL) scattering plane near (001), 

and no evidence of diffuse scattering is present. As the dominant 

difference between PMN and PZT lies in the huge difference in 

REF strength, these neutron data establish a direct causal link 

between strong REFs and the temperature-dependent, anisotropic diffuse scattering from lead-oxide, perovskite relaxors shown 

in the inset to panel (c). In the same vein, the dielectric permittivity data demonstrate that strong REFs are responsible for the 

relaxor-like behavior. Together these results imply the existence 

of a fundamental connection between the relaxor phase and the 

anomalous temperature-dependent diffuse scattering. We thus 

identify the relaxor order parameter with the static, anisotropic 

diffuse scattering associated with short-range polar order, as it 

marks the transition temperature from the high-temperature 

paraelectric phase (where it is zero) into the low-temperature 

relaxor state (where it is non-zero). This identification is consistent with the ideas of Imry and Ma who showed that magnetic 

systems with continuous symmetry break up into short-range 

ordered domains in the presence of random magnetic fields. In 

relaxors like PMN long-range ferroelectric order is stifled by the 

formation of analogous polar domains on cooling. By contrast 

our data show that no such domains form in ferroelectric PZT 

because the REFs are too weak (or absent).

It is well known that pseudo-rhombohedral compositions 

of PMN-xPT and PZN-xPT located near the MPB exhibit 

enormous piezoelectric coefficients; the values of the 

longitudinal piezoelectric coefficient d33 for single-crystal MPB 

compositions poled along [001] can exceed 2500 pC/N and 

are the largest known. The concepts of polarization rotation 

and adaptive phases were proposed to explain the ultrahigh 

electromechanical response in MPB systems like PZT and 

PMN-xPT. However it has been shown that the integrated 

neutron elastic diffuse scattering intensity in PMN-xPT, 

which from the fluctuation-dissipation theorem is a measure 

of the static susceptibility, and d33 share a similar composition 

dependence; both properties peak near the MPB and then drop 

precipitously in the tetragonal (Ti-rich) regime in which the 

relaxor phase is replaced by a conventional ferroelectric phase. 

Given our finding that PZT exhibits essentially no such diffuse 

scattering, one might expect that the corresponding value of d33

in PZT should be significantly smaller than that in PMN-xPT.

We find that this is indeed true; the maximum value of d33 we 

measured for MPB compositions of [001]-poled PZT single 

crystals is 1,200 pC/N [3]. Thus the optimal values of d33 in 

single-crystal PMN-xPT and PZN-xPT are approximately 

100 % greater than those in single-crystal PZT. Insofar as 

PZT and PMN-xPT are highly similar save for the strength of 

the REFs, our results indicate that the underlying nanometerscale, static, polar order in relaxors that is associated with the 

temperature-dependent diffuse scattering plays a seminal role 

in greatly amplifying the piezoelectric response beyond that 

in the non-relaxor PZT, which does not exhibit an equivalent 

nanometer-scale polar order. This behavior is not without 

precedent. In single crystals of highly magnetostrictive Galfenol 

(an alloy of magnetic Fe and non-magnetic Ga), a material that 

is often likened to a magnetic relaxor, both the neutron elastic 

diffuse scattering intensity and the longitudinal magnetostrictive 

coefficient λ100 increase dramatically as the system is doped 

towards a phase boundary and then decrease sharply as the 

boundary is crossed [4].

References

[1] I. Grinberg, P. Juhàs, P. K. Davies, A. M. Rappe, Phys. Rev. Lett. 

99, 267603 (2007).

[2] A. R., Akbarzadeh, S. Prosandeev, E. J. Walter, A. Al-Barakaty, 

L. Bellaiche, Phys. Rev. B 108, 257601 (2012).

[3] D. Phelan et al., Proc. Natl. Acad. Sci. USA, in press. 

[4] H. Cao et al., Phys. Rev. Lett. 102, 127201 (2009).
18 NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY – NIST CENTER FOR NEUTRON RESEARCH CHEMICAL PHYSICS

reorientational dynamics in LiBH4: effects of 

iodide substitution and nanoconfinement

N. Verdal1,2, T. J. Udovic1, and J. J. Rush1,2

1

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

2

 University of Maryland, College Park, MD 20742

The tetrahydroborate anion, BH–

4, has been 

actively investigated as a potential entity for 

hydrogen storage on-board hydrogen fuel cell 

powered vehicles due to an inherently favorable 

hydrogen mass fraction. As such, the lighter-metal 

borohydrides have undergone particularly intense scrutiny, 

although in their pristine states they display generally 

unfavorable hydrogen-cycling behavior. It has been a 

goal of a number of recent quasielastic neutron scattering 

(QENS) and NMR experiments to better understand 

this behavior and unravel the mechanistic details of BH–

4

reorientations in these materials in their pristine as well 

as chemically or morphologically altered states. For 

LiBH4, the lightest and best studied metal borohydride, 

there are lingering uncertainties with respect to how the 

reorientational mechanisms and mobilities are perturbed 

by either halide anion substitution (most notably, I-

) or 

confinement in nanopores, two potential strategies for 

ameliorating the thermodynamics, kinetics, and reversibility 

of dehydrogenation/hydrogenation. QENS, vibrational 

spectroscopy, and diffraction probes have been recently 

used at the NCNR over a wide range of wavevector and 

temperature to clarify reorientational behavior in these 

modified systems [1,2].

Whereas orthorhombic LiBH4 exhibits a transition at 

385 K to a hexagonal structure with much more rapid 

reorientational dynamics, the mixed salts maintain such a 

structure to very low temperatures with even more rapid 

reorientations. We have synthesized a 7Li11BH4-LiI solid 

solution, verified its hexagonal structure down to 4 K, and 

measured QENS spectra using both the DCS and HFBS 

spectrometers over a momentum transfer (Q) range of 0.2 Å-1 

to 6.5 Å-1 and at resolutions between 0.8 μeV and 1000 μeV. 

Results have been compared with similar measurements 

for pure a 7

Li11BH4. Elastic scattering scans measured on 

HFBS for LiBH4 and LiBH4-LiI are shown in Fig. 1, which 

illustrate the great change in the onset of neutron sensitive 

(10-9s

-1) reorientational dynamics with iodide substitution. 

In fact, the very broad dynamical range of the 1:1 mixed salt 

allows us to probe reorientations within the hexagonal phase 

down to very low temperatures.

The incoherent scattering function, S(Q,ω), for LiBH4-LiI 

(and for LiBH4) includes a combination of elastic, A0(Q), 

and quasielastic, Ai(Q), scattering as described by the 

expression:

S(Q,ω)= A 

0(Q)δ(ω)+ΣAi

(Q)L i(ω), (1)

whose functional forms are determined by the geometric 

details of the reorientational (or translational) motions of the 

BH–

4 ions [1,2]. The elastic and quasielastic lineshapes can be 

represented by delta, δ (ω), and Lorentzian, Li(ω), functions 

respectively. The measured spectrum at 125 K is shown 

in Fig. 2a, which can best be fitted using two Lorentzian 

components, combined with an elastic peak. The elastic 

incoherent structure factor, A0(Q), for these results shows a 

dramatic change in reorientational mechanism over a narrow 

temperature range, from a one-dimensional delocalized 

“orbit” motion of the three trigonal H atoms, with the fourth 

axial BH–

4 proton “immobile” (orbit model) at 125 K, to the 

additional “jump-exchange” of the axial protons with the 

orbiting trigonal H atoms (orbit-exchange model) by 200 K 

(Fig. 2b). This ability to track changes in reorientational 

motions is a vivid illustration of the power of the QENS 

technique. Raising the temperature to 250 K 

and measuring the A0(Q)with 1.7 Å neutrons to provide an 

extended Q range up to 6.4 Å-1 allows us to corroborate the 

more delocalized nature of the orbiting trigonal H atoms 

(green), ruling out the more discrete six-fold C6-localized 

orbit-exchange model (maroon). Also shown is the measured 

A0(Q) for LiBH4 at a much higher temperature, which 

closely resembles the mixed-salt result.

FIGURE 1: The elastic scattering intensity of bulk LiBH4 (black), LiBH4-LiI (blue), 

and LiBH4 in 4 nm carbon pores (green) as a function of temperature. Vertical 

error bars in all figures denote ± 1σ.
2013 ACCOMPLISHMENTS AND OPPORTUNITIES 19CHEMICAL PHYSICS

In addition to LiBH4 in a mixed crystal, we have recently 

extended our measurements to a study of LiBH4 confined 

in nanoporous carbon (NPC) materials, including NPCs 

possessing 4 nm diameter, hexagonally arranged, cylindrical 

pores [1]. The neutron vibrational spectra measured for the 

LiBH4 in NPCs show a distinct broadening of the BH–

4

torsional band compared to bulk LiBH4, which clearly 

indicates a change in reorientational dynamics. Moreover, 

the measurement of quasielastic spectra on the NPCs using 

both HFBS and DCS spectrometers again allowed us to 

follow the BH–

4 reorientational behavior over a wider range of 

temperature. As shown in Fig. 1, the temperature region for 

“neutron sensitive” reorientational dynamics of LiBH4 in 4 nm 

NPC begins lower and is more extensive than for pure LiBH4.

The nature of the BH–

4 quasielastic scattering in the NPC 

is different from either pure LiBH4 or the LiBH4-LiI 

compound. The best fit to the quasielastic data requires two 

Lorentzian components, roughly an order of magnitude apart 

in width. It is thus most probable that they represent two 

independent populations of BH–

4 anions in very different 

environments. In Fig. 3a, we plot the A0(Q) derived 

from the results at 330 K, a temperature at which the two 

quasielastic components have about the same intensity. 

This strongly suggests that the two BH–

4 populations are 

associated with a bulk-like interior region reorienting 

at a slower rate and an interfacial layer reorienting at a 

significantly greater rate (see Fig. 3a inset), with an average 

thickness of ≈ 0.6 nm. The A0(Q) at 330 K (diamonds) 

is well fit by a model describing two-fold or three-fold 

jumps around a single axis; while at 400 K (stars), it is best 

fit by a three-dimensional rotational diffusion model. As 

the temperature is raised above 330 K, both components 

become more rotationally diffusive. Moreover, at 400 K, the 

fraction of faster reorientations increases, suggesting either 

an increased 1 nm interfacial thickness, or the transition 

of some of the interior LiBH4 from a reorientationally 

slow orthorhombic structure to a reorientationally more 

rapid hexagonal structure. Finally, in Fig. 3b we show 

the Arrhenius plots of the linewidths for both quasielastic 

features of LiBH4 confined in a 4 nm pore, compared to 

the results for pure LiBH4. The linewidth for the broader 

quasielastic component is distinct from the narrower 

component and similar in width to the limited results shown 

for the high-temperature hexagonal phase of LiBH4. The 

reorientational activation energies determined from an 

Arrhenius fit for LiBH4 in 4 nm NPC are (16 ± 1) kJ/mol 

and (10.6 ± 0.7) kJ/mol, demonstrating the great change 

in BH–

4 dynamics from the core to interfacial region, and 

somewhat reduced from the (19.2 ± 0.8) kJ/mol determined 

for the bulk.

FIGURE 2: a) The QENS spectrum of LiBH4-LiI at 125 K with 2.75 Å wavelength 

neutrons collected at Q = 2.4 Å-1 (black), with the fitted function (red), 

consisting of a delta (white) and two Lorentzian (blue and green) functions. 

b) The observed A0(Q) for LiBH4-LiI at 125 K (blue diamonds), and 250 K (black 

circles), compared with the orbit model (blue line), the orbit-exchange model 

(green line), and the C6-localized orbit-exchange model (maroon line). A 

schematic of BH4 reorientational jumps is depicted in the inset. The observed 

A0(Q) for bulk LiBH4 at 400 K (open circles) is shown for comparison.

These results exemplify the utility of high-Q QENS 

measurements to track the mechanistic evolution of 

molecular reorientations in general. For the current systems, 

modified BH–

4 dynamics turns out to be a sensitive indicator 

of non-bulk-like LiBH4 perturbations due to either iodide 

substitution or nanoconfinement. The relationship between 

these perturbations and modified hydrogen storage and 

release properties is yet to be determined.

FIGURE 3: a) The A0(Q) of LiBH4 confined in a 4 nm carbon pore at 330 K (dark 

cyan diamonds) compared with a C2|C3 reorientational jump model (cyan), and 

at 400 K (blue stars) compared with the C6-localized orbit-exchange model 

(maroon) and isotropic rotational diffusion (black). The inset is a schematic 

of LiBH4 confined in a 4 nm pore carbon scaffold. b) An Arrhenius plot of 

quasielastic linewidths of LiBH4 at the interface (blue), and the interior (green) 

of a 4 nm carbon pore are compared with bulk LiBH4 (red).

References

[1]. N. Verdal, T.J. Udovic, J.J. Rush, X. Liu, E.H. Majzoub, M.R. 

Hartman, J.J. Vajo, A.F. Gross, J. Phys. Chem. C 117 (35) 

17983 (2013). 

[2]. N. Verdal, T.J. Udovic, J.J. Rush, H. Wu, A.V. Skripov, J. Phys. 

Chem. C 117, 12010 (2013).
20 NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY – NIST CENTER FOR NEUTRON RESEARCH CONDENSED MAT TER

Fractionalized excitations in a spin-1/2 kagome 

lattice antiferromagnet

T.-H. Han1, J. S. Helton2, S. Chu1, D. G. Nocera1, J. A. Rodriguez-Rivera2,3, C. Broholm2,4, and Y. S. Lee1

1

Massachusetts Institute of Technology, Cambridge, MA 02139

2

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

3

University of Maryland, College Park, MD 20742

4

The Johns Hopkins University, Baltimore, MD 21218

Materials with atomic magnetic moments 

arranged on a crystalline lattice are ubiquitous 

in nature and have numerous technological 

applications. Typically these materials will 

display long range magnetic order at low temperatures. 

However, some two-dimensional lattices instead give rise to 

a new state of quantum magnetic matter: the spin liquid. 

A quantum spin liquid has a magnetic ground state that 

displays strong short range fluctuating spin correlations but 

no static order down to low temperatures, despite strong 

antiferromagnetic interactions between neighboring spins. 

Neutron scattering measurements on ZnCu3(OD)6Cl2, 

also known as herbertsmithite, have revealed a continuous 

energy spectrum of magnetic fluctuations [1] – evidence of 

fractionalized quasiparticles in the spin liquid ground state of 

this frustrated magnet. 

Quantum spin liquids have attracted a great deal of attention 

in condensed matter physics since Anderson’s seminal 

proposal of the “resonating valence bond” state four decades 

ago [2], yet real materials displaying this ground state are rare. 

A particularly promising system in which to search for spin 

liquid physics is the spin-1/2 kagome lattice antiferromagnet. 

The strong quantum fluctuations inherent to spin-1/2 

moments and the extensive ground state degeneracy of 

antiferromagnetically interacting spins on the kagome 

lattice (Fig. 1) combine to destabilize long range order. The 

mineral herbertsmithite, ZnCu3(OD)6Cl2, features spin1/2 Cu2+ ions arranged on a kagome lattice with successive 

layers magnetically isolated by layers of diamagnetic Zn2+

ions. Magnetic susceptibility measurements display a CurieWeiss temperature of -300 K, which indicates strong nearest 

neighbor antiferromagnetic interactions (J ≈ 17 meV). 

Previous work on powder samples of herbertsmithite [3] 

revealed short range dynamic spin correlations with no sign 

of an energy gap in the excitation spectrum or of long range 

magnetic order down to mK temperatures. While the low 

energy dynamics of herbertsmithite appear to be complicated 

by magnetic Cu2+ impurities occupying sites in the nominally 

diamagnetic Zn layers, this material remains the best 

realization of the spin-1/2 kagome lattice available for 

experimental study and one of only a few materials with a 

quantum spin liquid ground state.

FIGURE 1: The kagome lattice, consisting of corner-sharing triangles. In 

herbertsmithite, spin-1/2 copper ions are arranged on a kagome lattice with an 

antiferromagnetic (J ≈ 17 meV) interaction between nearest-neighbor spins.

Many early neutron spectroscopy measurements on 

ZnCu3(OD)6Cl2 were carried out on powder samples. 

However, powder experiments can be ambiguous because 

the direction of the neutron’s momentum change with 

respect to the crystalline lattice is unknown. In order to carry 

out more precise measurements, single crystal samples of 

herbertsmithite were synthesized through a new chemical 

process that involved tubes of dissolved precursor material 

subjected to slight temperature gradients where the sample 

synthesis was allowed to proceed for up to 10 months. This 

method succeeded in producing multiple single crystal 

samples of herbertsmithite with masses up to 320 mg. 

Fifteen samples were co-aligned on an aluminum sample 

holder, producing a total sample of 1.2 g suitable for neutron 

spectroscopy.

Neutron spectroscopy measurements on this single crystal 

sample were carried out using the Multi-Axis Crystal 

Spectrometer (MACS). MACS allows researchers to map 

out short range spin correlations by measuring the dynamic 
2013 ACCOMPLISHMENTS AND OPPORTUNITIES 21CONDENSED MAT TER

structure factor, S(Q, w), over a broad swath of reciprocal

space, Q, at a few fixed energy transfers (ħw). The dynamic

structure for herbertsmithite, cooled to 1.6 K, is shown for 

energy transfers of 6 meV (Fig. 2a) and 2 meV (Fig. 2b). 

These data confirm that the ground state of herbertsmithite 

features dynamic short-range correlations, as they lack the 

sharp spin wave dispersion features that would arise for 

an ordered magnet. Even non-frustrated magnets without 

long range magnetic order at low temperatures, such as the 

spin-1/2 square lattice antiferromagnet La2CuO4, develop 

significant antiferromagnetic correlations and display low 

energy scattering that is peaked near specific points in Q

space. The low energy spin dynamics in herbertsmithite, 

however, give rise to broad ridges of magnetic neutron 

scattering that extend over several Brillouin zones. The 

neutron scattering pattern is quite similar to that expected 

from uncorrelated nearest-neighbor antiferromagnetic dimers 

(Fig. 3), though the experimental ridges are narrower in 

Q space suggesting spin-correlations beyond the nearest 

neighbor. 

FIGURE 2: Dynamic structure factor of herbertsmithite at 1.6 K measured 

on the MACS spectrometer, with energy transfers of 6 meV (a) and 2 meV 

(b). The color scale is given by the bar on top, in units of barn/(eV steradian 

formula unit).

A further hallmark of a quantum spin liquid is the presence 

of exotic quasiparticle spin excitations carrying fractional 

quantum numbers. While the conventional spin wave 

excitations of an ordered magnet carry a spin quantum 

number of S = 1, the spinon excitations predicted for a 

quantum spin liquid consist of multiple spin-half (S = 1/2) 

excitations into which spin waves fractionalize. These exotic 

excitations have been previously observed in one-dimensional 

spin chains such as KCuF3, but have not been observed 

in two-dimensional magnetic systems. Since a neutron 

scattering experiment which generates ΔS = ± 1 excitations 

based on quantum selection rules will excite multiple spinons 

simultaneously, the resulting spectrum will feature a broad 

continuum of scattering extending over energy transfers 

from zero up to a maximum comparable to the exchange 

interaction J. The measured spectrum of ZnCu3(OD)6Cl2

fits this prediction, as a continuum of inelastic scattering is 

observed with a Q-space pattern similar to that shown in 

Fig. 2 stretching up to energy transfers of at least 11 meV.

FIGURE 3: Calculated structure factor for uncorrelated nearest-neighbor dimer 

singlets on a kagome lattice.

In two-dimensional antiferromagnets the combination of 

geometric frustration where the triangular plaquettes of the 

lattice prevent any simple collinear order and strong quantum 

fluctuations can lead to novel ground states of quantum 

magnetic matter such as the spin liquid. The spin-1/2 

Heisenberg antiferromagnet on the kagome lattice is a wellstudied theoretical model expected to display such an exotic 

ground state. We conclude that the mineral ZnCu3(OD)6Cl2

(herbertsmithite) is well described by this model and displays 

a spin liquid ground state with fluctuating short range 

correlations and no long range order down to the lowest 

temperatures measured. The spectrum of neutron scattering 

at fixed momentum transfer is a broad continuum extending 

to at least 11 meV. This is arguably the first experimental 

evidence for fractionalized excitations in a two-dimensional 

magnet, confirming an important prediction regarding 

quantum spin liquids and providing a starting point for 

further theories on quantum magnetism.

References

[1] T.-H. Han, et al., Nature 492, 406 (2012).

[2] P. W. Anderson, Mater. Res. Bull. 8, 153 (1973).

[3] J. S. Helton, et al., Phys. Rev. Lett. 98, 107204 (2007); 

P. Mendels, et al., Phys. Rev. Lett. 98, 077204 (2007).
22 NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY – NIST CENTER FOR NEUTRON RESEARCH CONDENSED MAT TER

Novel coexistence of half-metallic itinerant 

ferromagnetism with local-moment 

antiferromagnetism in Ba0.60K0.40Mn2As2

A. Pandey1, B. G. Ueland1, S. Yeninas1, A. Kreyssig1, A. Sapkota1, Y. Zhao2,3, J. S. Helton2, J. W. Lynn2, 

R. J. McQueeney1

, Y. Furukawa1, A. I. Goldman1, and D. C. Johnston1

1

Ames Laboratory and Iowa State University, Ames, IA 50011

2

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

3

University of Maryland, College Park, MD 20742

The discovery of high-temperature superconductivity 

in iron pnictides in 2008 [1] opened up an 

entirely new system for exploring insulating or 

narrow-band metallic behavior since some of these 

materials display aspects of both local-moment and itinerant 

magnetism. An important related material is BaMn2As2, 

which has the same tetragonal crystal structure as the hightemperature superconductor parent compound BaFe2As2. 

BaMn2As2 has an insulating ground state exhibiting collinear 

local-moment antiferromagnetic (AFM) order below 

TN = 625 K. Each isotropic, S = 5/2 Mn2+ ion has an ordered 

magnetic moment m = 3.9 mB/Mn which is oppositely 

directed to the moment of each of its nearest-neighbor Mn2+

ions [2]. BaMn2As2 can be made metallic by substituting 

K for Ba to form hole-doped Ba1-xKxMn2As2 [3,4]. In this 

system we have discovered a novel magnetic structure at low 

temperatures in single crystals of metallic Ba0.60K0.40Mn2As2

[5]. This structure consists of ferromagnetism (FM) of the 

itinerant doped holes below a Curie temperature TC ≈ 100 K 

along with collinear Mn local-moment AFM (TN = 480 K), 

where the ordered moments in the two magnetic structures 

are aligned perpendicular to each other. Furthermore, the 

FM at T → 0 arises from complete spin polarization of the 

doped holes, called half-metallic FM. This FM component 

was not present in the previously studied samples of 

Ba1-xKxMn2As2 with K concentrations of x = 0.016 and 

x = 0.05 [3]. It is qualitatively different from the halfmetallic FM in La1-xCaxMnO3, for example, [6] where 

the conduction electron moments are polarized by strong 

coupling to the FM-ordered local Mn moments and hence 

align parallel to them. 

FIGURE 1: (a) Magnetic susceptibility χ = M/H versus T of Ba0.60K0.40Mn2As2

[5]. Inset: FM ordered moment μFM at low T versus x in Ba1-xKxMn2As2 [5,6]. 

The dashed line is the expected behavior for full doped-hole spin polarization 

with μFM = xgS μB/f.u., g = 2.25 and S = 1/2 (f.u. means formula unit). (b) Mab 

versus H at 1.8 K [5]. Upper inset: Expanded plot of Mab (H ) at 1.8 K. Lower 

inset: Mab (H ) isotherms between 5 K and 300 K.

The local-moment magnetism of Ba1-xKxMn2As2 is very 

robust, with an ordered moment that is nearly constant 

at m ≈ 4.0 mB/Mn as the doping level changes from the 

insulating composition x = 0 to metallic compositions from 

x = 0.016 to x = 0.40 (the range studied). The moments are 

oriented along the c-axis throughout the doping series [7]. 

Furthermore, the TN associated with the Mn local moments 

decreases by only 20 % from 625 K for x = 0 to 480 K for 

x = 0.40. Due to this robust nature of the Mn local-moment 

AFM, the anisotropy of the magnetic susceptibility c(T) of

Ba0.60K0.40Mn2As2 was expected to be small and similar to 

that of undoped BaMn2As2 [2]. Surprisingly, the cab with

H || ab-plane instead exhibits a huge enhancement on cooling 
2013 ACCOMPLISHMENTS AND OPPORTUNITIES 23CONDENSED MAT TER

below 100 K as shown in Fig. 1(a), indicating the occurrence 

of a FM transition below TC ≈ 100 K with the FM ordered 

moments oriented in the ab-plane [the c

(T→0) value is 

attributed to a small (≈ 4 ̊) misalignment of the field with the 

c-axis of the crystal]. This FM below 100 K coexists with the 

AFM ordering of the Mn spins that exhibit AFM ordering 

below TN = 480 K. 

The FM is confirmed in Fig. 1(b) from Mab(H) 

measurements at 1.8 K. The data show that Mab(H) very 

quickly saturates to a nearly constant value at fields above 

about 10 mT. Extrapolating the high-field linear behavior to 

zero gives mFM(T = 1.8 K) = 0.45(1) mB/f.u. The expanded 

plot in the upper inset shows that the FM is extremely 

soft since the saturation is nearly complete at 10 mT and 

the coercive field is only about 1 mT. Mab(H) isotherms 

obtained both above and below 100 K are shown in the lower 

inset of Fig. 1(b). The FM spontaneous magnetization is 

clearly visible in the isotherms at 75 K and below.

One possible explanation for the in-plane FM below TC in 

Ba0.60K0.40Mn2As2 originates from canting (tilting) of the 

already-established Mn ordered moments (TN = 480 K) 

along the c-axis towards the ab-plane. However, 75As NMR 

data argue against this possibility [5], and such a canting 

would also require a lattice distortion to remove the inversion center between the Mn atoms, which is not detected 

in high-resolution x-ray diffraction measurements down to 

10 K [5]. To rule out this canting possibility unambiguously 

and to directly observe this new FM, field-dependent neutron diffraction data were obtained on BT-7, and the data for 

T = 5 K are shown in Fig. 2 [5]. Similar intensity increases 

are observed for a number of reflections, but the (101) peak 

seen in Fig. 2(d) is of special importance since FM ordering 

of the Mn local moments will only contribute to Bragg peaks 

with h + k even and l even. Thus the increase in these intensities cannot be due to a canting of the Mn moments, and 

therefore must be due to FM ordering of the itinerant doped 

holes. As shown in the inset of Fig. 1(a), the saturation moment of all the doped hole spins agrees quantitatively with 

the observed value for T  0. This type of itinerant FM is 

called half-metallic, which interpretation is also supported by 

a fit to the electrical resistivity measurements.

FIGURE 2: Integrated intensity versus H for four Bragg peaks at T = 5 K. The 

curves are fits to the M 2

ab (H ) data in Fig. 1(b). Uncertainties are statistical in 

origin and represent one standard deviation.

In summary, our magnetization, NMR, electrical resistivity, 

and x-ray and neutron diffraction measurements of 

Ba0.60K0.40Mn2As2 crystals reveal that this compound 

exhibits a novel magnetic structure in which half-metallic 

FM coexists with local-moment AFM of the Mn spin 

lattice, where the ordered moments of these two magnetic 

substructures are perpendicular to each other. The 

microscopic origin of the surprising half-metallic itinerant 

FM, and the mechanism behind the perpendicular alignment 

of the FM and AFM ordered magnetic structures, are 

interesting new questions to be explored.

References

[1] D. C. Johnston, Adv. Phys. 59, 803 (2010).

[2] D. C. Johnston, R. J. McQueeney, B. Lake, A. Honecker, M. E. 

Zhitomirsky, R. Nath, Y. Furukawa, V. P. Antropov, Y. Singh, 

Phys. Rev. B 84, 094445 (2011).

[3] A. Pandey, R. S. Dhaka, J. Lamsal, Y. Lee, V. K. Anand, A. 

Kreyssig, T. W. Heitmann, R. J. McQueeney, A. I. Goldman, 

B. N. Harmon, A. Kaminski, D. C. Johnston, Phys. Rev. Lett. 

108, 087005 (2012).

[4] J.-K. Bao, H. Jiang, Y.L. Sun, W.-H. Jiao, C.-Y. Shen, H.-J. 

Guo, Y. Chen, C.M. Feng, H.-Q. Yuan, Z.-A. Xu, G.-H. Cao, 

R. Sasaki, T. Tanaka, K. Matsubayashi, Y. Uwatoko, Phys. Rev. 

B 85, 144523 (2012).

[5] A. Pandey, B. G. Ueland, S. Yeninas, A. Kreyssig, A. Sapkota, Y. 

Zhao, J. S. Helton, J. W. Lynn, R. J. McQueeney, Y. Furukawa, 

A. I. Goldman, D. C. Johnston, Phys. Rev. Lett. 111, 047001 

(2013).

[6] Y. Tokura, Rep. Prog. Phys. 69, 797 (2006).

[7] J. Lamsal, G. S. Tucker, T. W. Heitmann, A. Kreyssig, A. Jesche, 

A. Pandey, W. Tian, R. J. McQueeney, D. C. Johnston, A. I. 

Goldman, Phys. Rev. B 87, 144418 (2013).
24 NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY – NIST CENTER FOR NEUTRON RESEARCH CONDENSED MAT TER

Phonon-driven superconductivity in the 

vicinity of ferroelectric and charge density 

wave (CDW) ordering in La(O,F)BiS2 

T. Yildirim1, 2

1

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

2

University of Pennsylvania, Philadelphia, PA 19104

S

uperconductivity – a phenomenon first documented in 

1911 – remains one of the most challenging subjects 

of condensed matter physics. Very recently a new 

family of layered materials containing BiS2 planes 

[1] was discovered to be superconducting at temperatures 

up to 10 K. These new systems REOxF1-xBiS2 (RE=La, 

Nd, Pr, and Ce) are structurally similar to the layered, ironbased superconductors LaOxF1-xFeAs, and in both cases the 

superconductivity is achieved by F-doping. This similarity 

has raised the exciting question of whether or not the 

superconducting mechanism in the BiS2 system is related to 

that in the iron pnictides. 

The fundamental question is whether or not the observed Tc

in this new system can be understood within a conventional 

electron-phonon (el-ph) coupling framework, or is a more 

exotic mechanism responsible for the superconducting 

pairing? In this study, [2] we present state-of-the-art first 

principles calculations that directly address this question. 

We find that BiS2 is a strong electron-phonon coupled 

superconductor in close proximity to competing ferroelectric 

and CDW phases. Our results suggest new directions with 

which to tune the balance between these phases and increase 

Tc in this new class of materials. 

Fig. 1 shows the tetragonal cell of LaOxF1-xBiS2, which 

consists of two types of atomic layers; namely the LaO 

spacer and electronically active BiS2 bilayer. Upon replacing 

some of the oxygen atoms in the LaO layer with F, one can 

control the charge transfer to BiS2 bilayer and thus tune the 

electronic properties as shown in Fig. 1. The undoped parent 

compound is a band-insulator with a gap of ≈ 1 eV. Upon 

electron doping, we start to fill the empty states in a rigidband fashion, turning the insulating parent compound into 

a metallic system. The density of states (DOS) at the Fermi 

level, N(EF), increases with increasing electron doping and 

becomes maximal at the half filling x = 0.5. 

FIGURE 1: (a) Crystal structure of LaOxF1-xBiS2 (x = 0.5). (b) Electronic DOS 

of LaOxF1-xBiS2 as a function of F-doping x. For clarity the curves are shifted 

vertically except x = 0.5. 

One of the most interesting results shown in Fig. 1 is that 

N(EF) is quite high at half-filling (x = 0.5) and EF coincides 

with a peak in the density of states. This usually suggests some 

sort of instability due to a Van Hove singularity. In order to 

check this, we calculated [2] phonon dispersion curves of 

the parent (x = 0) and half doped (x = 0.5) systems. To our 

surprise, we find that the undoped system shows instability 

near the center of the Brillouin zone while the doped system 

has instabilities at M (π,π). In order to have a better insight 

into the nature of these unstable phonons, we carried out 

total energy calculations as the system was distorted by the 

modes having the most negative energy. Fig. 2a shows the 

most unstable soft phonon Eu at the center of the Brillouin 

zone for x = 0. The S atoms move towards Bi atoms along 

a- or b-axis (two –fold degenerate) and slightly lower the 

energy of the system by ≈ 1 meV. It is remarkable that in 

the distorted phase, the inversion symmetry is broken and a 

large spontaneous polarization of P = 9.9 μC/cm2 is induced 

despite the rather small displacements. However, solving the 

Schrödinger equation for this shallow potential, we obtained 

energy levels that are above the potential minimum. Hence, 

the system should be dynamically disordered due to zeropoint motions and should appear as tetragonal. 

Fig. 2b shows the total energy in the √2 x √2 cell of the 

tetragonal structure for x = 0.5 as it is distorted according 

to the most negative energy phonon at (π,π). Unlike the 
2013 ACCOMPLISHMENTS AND OPPORTUNITIES 25CONDENSED MAT TER

parent compound, the distortion lowers the system energy 

significantly, causing S atoms to move away by 0.16 Å from 

the high symmetry site. Solving the resulting one-dimensional 

potential curve numerically, we obtained the energy levels, 

which are bound to the local minimum of the distortion. 

Hence, unlike the x = 0 case, DFT calculations predict that 

the x = 0.5 system should distort from tetragonal symmetry. 

Indeed, we determined that the fully stable optimized structure 

has the √2 x √2 unit cell with symmetry P2212 and that it 

shows a rather interesting rearrangement of Bi and S atoms in 

the BiS2 plane, as shown in Fig. 3. We denote this distorted 

structure as the CDW phase, due to the sinusoidal distortion 

of the Bi and S atoms as shown by red dashed lines in Fig. 3.

We next address the nature of superconductivity found in 

these BiS2 layered systems. We calculate the el-ph coupling in 

the CDW phase by the frozen-phonon method. The results 

are summarized in Fig. 3. We obtain quite large electronphonon coupling  = 0.6 and a logarithmic frequency

average ωlog = 122 K, which gives a Tc of 6 K. This value is 

in excellent agreement with the reported experimental values 

of Tc that vary from 3 K to 10 K, depending on the level of 

doping. Inspecting the modes which give the highest el-ph 

coupling, we estimate that about 90 % of  comes from inplane Bi and S phonons while the remaining 10 % is due to

phonons along the c-axis. There are two bands of phonons 

near (5 to 10) meV and (15 to 25) meV. The phonons in the 

lower energy band are due to coupled Bi and S motion while 

the phonons in the high energy bands are due to almost pure 

S oscillations. In Fig. 3, we also show the total phonon density 

of states along with the atomic-projections of the DOS. 

FIGURE 2: Total energy as the system is distorted by the most negative energy 

phonons in the tetragonal cell of LaOBiS2 at the center of the Brillouin zone 

(top) and in the √2 x √2 cell of LaO0.5F0.5BiS2 (bottom). The insets show the 

sketch of the unstable phonons. Horizontal dashed red lines show the energy 

levels of the one-dimensional potential (red curve). The calculated polarization, 

lattice parameters and the displacement of S atom are also indicated.

FIGURE 3: Top: The optimized structure of the BiS2 plane in the √2 x √2 CDW 

phase of LaO0.5F0.5BiS2. Large pink and small yellow spheres are Bi and S, 

respectively. Dashed red line is to guide the eye, indicating the sinusoidal 

distortion of the atoms. The white rectangle indicates the unit cell of the CDW 

phase. Middle: Eliashberg functions in the fully optimized CDW structure (top). 

El-ph coupling constant, λ, Tc , and ωlog are also given. The total and atomicprojected phonon DOS are shown in the bottom panel. 

In conclusion, we have discovered rather unusual structural 

and dynamical properties of LaOBiS2 with electron doping. 

The large-amplitude in-plane S-atom displacement controls 

the structural properties and gives rise to large el-ph coupling. 

It would be interesting to measure the isotope effect for the S 

atom, which may be unconventional. Our results also suggest 

that thin films of BiS2 on various substrates may exhibit 

unusual properties due to epitaxial strain at the interface. 

New materials with similar structures but with BiS2 plane 

could be quite interesting due to smaller mass of oxygen 

atom, which gives higher phonon energies, and in turn higher 

Tc . It is too early to say which of these predictions from our 

calculations will be demonstrated experimentally. However 

it is clear that the BiS2 based layered systems are very rich 

in physics, involving nearly ferroelectric soft phonons and 

CDW ordering along with strongly coupled electron-phonon 

superconductivity.

References

[1] Y. Mizuguchi, et al., Phys. Rev. B 86, 220510 (R) (2012).

[2] T. Yildirim, Phys. Rev. B 87, 020506 (R) (2013). 
26 NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY – NIST CENTER FOR NEUTRON RESEARCH CONDENSED MAT TER

Interfacial ferromagnetism in CaRuO3 / CaMnO3

C. He1, A. J. Grutter1,2, M. Gu3, N. D. Browning3, Y. Takamura3, B. J. Kirby4, J. A. Borchers4, J. W. Kim5, 

M. R. Fitzsimmons5

, X. Zhai1, V. V. Mehta1,2, F. J. Wong1, and Y. Suzuki1,2,6

1

University of California, Berkeley, CA 94720

2

Lawrence Berkeley National Laboratory, Berkeley, CA 94720

3

University of California, Davis, CA 95616

4

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

5

Los Alamos National Laboratory, Los Alamos, NM 87545

6

Stanford University, Stanford, CA 94305

There is a wide spectrum of phenomena that occur 

at the interface between dissimilar materials. In 

particular, the interface between two distinct but 

strongly correlated materials can constitute an 

environment very different from that corresponding to either 

of the materials alone, leading to emergent properties [1]. 

Among these is ferromagnetism that emerges at the interface 

between thin layers of non-ferromagnetic complex oxides. Such 

emergent ferromagnetism is fascinating from a fundamental 

perspective, and also holds great potential for applications in 

electronic devices. Only a few examples of this type of emergent 

ferromagnetism have been reported, typically dealing with 

interfaces between two different types of antiferromagnetic 

insulators [1,2]. Alternatively, ferromagnetism has also 

been observed for multilayers comprised of a paramagnetic 

metal CaRuO3 (CRO) and an insulating antiferromagnet 

CaMnO3 (CMO) [3]. Theory based on the double exchange 

mechanism predicts that this ferromagnetism arises from just 

one unit cell (u.c.) of ferromagnetic CMO at each CMO/

CRO interface [4]. However, actually determining the origin 

of ferromagnetism in these materials is problematic using 

only common laboratory magnetometry instruments, which 

measure just the total magnetic moment of the entire sample, 

with no spatial information. Thus, to experimentally test the 

double exchange model of interfacial ferromagnetism for this 

system, we have fabricated a series of high quality [CRO3 / 

CMON]10 superlattices (N = 3 to N = 12) on (001) SrTiO3

(STO) substrates, and studied them with several techniques that 

probe the collective magnetic behavior, and the depth resolved 

structure and magnetization, including superconducting 

quantum interference device (SQUID) magnetometry, scanning 

transmission electron microscopy (TEM), and polarized neutron 

reflectometry (PNR) [5].

The superlattices of CRO/CMO were grown by pulsed laser 

deposition with a KrF laser. The atomic abruptness of the 

interfaces in the superlattices was probed via x-ray reflectivity 

(XRR) and transmission electron microscopy (TEM). Fig. 

1(a) shows a representative XRR scan for a CRO3 / CMO12

superlattice. The low and high frequency oscillations correspond 

to the superlattice period and the total thickness, respectively. 

Fig. 1(b) shows an atomic resolution Z-contrast TEM image 

where the CRO layers appear brighter due to the localization 

of the heavy element Ru. Both XRR and TEM measurements 

indicate high quality CRO / CMO interfaces with minimal 

diffusion.

FIGURE 1: (a) X-ray reflectivity scan of CRO3 / CMO12. (b) cross sectional atomic 

resolution Z-contrast TEM image of CRO3 / CMO15 (the left half of the image is 

noise reduced using the principle component analysis).

To directly probe the interfacial magnetic profile, we used 

the NG-1 Reflectometer to perform PNR experiments on an 

N = 10 superlattice after the sample had been cooled to 5 K 

in 0.82 T. The neutron beam was polarized alternately up or 

down with respect to a magnetic field H applied to the sample, 

and the spin-dependent specular reflectivity was measured 

as a function of wavevector transfer Qz. For this scattering 

geometry, the spin-up and spin-down non-spin-flip reflectivities 

are functions of the depth profiles ρ(z), the nuclear scattering 

length density, and M(z), the magnetization component parallel 

to H. Thus ρ(z) and M(z) were deduced by model fitting the 

PNR spectra using the Refl1D software package. Fig. 2(a) shows 

the fitted non-spin-flip PNR data for the N =10 superlattice 

plotted as Fresnel normalized reflectivity (reflectivity scaled 

by the theoretical reflectivity of the bare STO substrate). The 

salient features of the spectra are the low Qz oscillatory spin 

splitting, and the spin splitting of the first-order superlattice 

Bragg peak near Qz ≈ 1.4 nm-1. The data are well fit by a 

model where ferromagnetism is assumed to arise solely from 

one u.c. of interfacial CMO, as shown in Figs. 2(b) and 2(c). 

This solution is not unique, as models featuring 2 magnetized 

u.c. of interfacial CMO, or uniformly magnetized CRO yield 

qualitatively similar fits to the data. However, we can strictly rule 
2013 ACCOMPLISHMENTS AND OPPORTUNITIES 27CONDENSED MAT TER

out other competing models, including those featuring magnetic 

moment that arises from a uniformly magnetized superlattice 

and uniformly magnetized CMO layers. These models cannot 

reproduce the spin dependence of the Bragg peak and the spin 

splitting at low Qz. Therefore, the PNR data are consistent with 

magnetic moment arising from 1 u.c. of CMO at the CMO/

CRO interfaces, and conclusively confirm a periodic distribution 

of moment. Similar PNR measurements of an N =11 sample 

measured using Asterix at the Los Alamos Neutron Science 

Center gave consistent results. 

FIGURE 2: (a) PNR spectra for CRO3 / CMO10 measured at 5 K in 0.82 T after 

field cooling. Inset highlights low Qz scattering. Lines are model fits to the 

data and error bars on the data are one standard deviation. (b) Nuclear depth 

profile. (c) Magnetic depth profile corresponding to 1 u.c. interfacial CMO 

magnetization.

Having confirmed the interfacial nature of the ferromagnetism, 

we now consider magnetometry measurements. Fig. 3 shows 

the hysteresis loops of four representative samples (N = 3, 4, 

8, 10) measured at a temperature of 10 K, after cooling in 

either a positive or negative 5 T magnetic field. For the N = 3 

superlattice [Fig. 3(a)], the +5 T and -5 T field cooled loops are 

basically identical, and are both centered about H = 0. For the 

N = 4 superlattice [Fig. 3(b)], the positive and negative field 

cooled loops exhibit small but distinct shifts of -/+ 0.018 T, 

respectively, and are no longer precisely centered about H = 0. 

These shifts are indicative of exchange bias, a phenomenon 

most often observed in systems containing ferromagnetic/ 

anitferromagnetic interfaces where uncompensated spins in the 

antiferromagnetic layer couple to spins in the ferromagnetic 

layer, biasing them along a particular direction. For superlattices 

with N = 8 [Fig. 3(c)] and N = 10 [Fig. 3(d)], the exchange bias 

field (HEB, the magnitude of the horizontal shift) increases to 

0.09 T and 0.12 T, respectively. Our observation of exchange 

bias implies the presence of a ferromagnetic layer strongly 

magnetically coupled to an adjacent antiferromagnetic layer. 

Thus, the onset of exchange bias in the N = 4 superlattice 

indicates the presence of antiferromagnetic ordering in the 

4 CMO layers. If we make a reasonable assumption that at least 

2 u.c. of CMO is necessary for antiferromagnetic ordering, that 

leaves only one u.c. of ferromagnetic CMO at each interface in 

the N = 4 superlattice to contribute to the ferromagnetism. For 

the N = 8 and N = 10 superlattices, HEB increases due to the 

increased pinning force from thicker adjacent antiferromagnetic 

CMO layers. However, the saturation (i.e., maximum) magnetic 

moment is similar to that of the N = 4 superlattice, indicating 

that the number of layers contributing to the ferromagnetism 

(i.e. 1) does not change from N = 4 to N = 10. These results 

indicate that the interfacial ferromagnetism identified by PNR 

indeed originates from only 1 u.c. of CMO at each interface. 

FIGURE 3: Field dependent magnetic moment of (a) N = 3, (b) N = 4, (c) N = 8, 

and (d) N = 10 CRO3 / CMON superlattices. The measurements were done after 

+5 T (black squares) and -5 T (red circles) field cooling from 300 K. 

In summary, we have found ferromagnetism in CRO3 / CMON

superlattices on STO (001) substrates, and have demonstrated 

that it arises from a solitary unit cell of magnetized CMO at 

each interface. This finding is consistent with density functional 

theory calculations that attribute the ferromagnetism to double 

exchange arising from CRO - CMO charge transfer at the 

interfaces.

References

[1] A. Bhattacharya, S. J. May, S. G. E. te Velthuis, M. 

Warusawithana, X. Zhai, Bin Jiang, J.-M. Zuo, M. R. 

Fitzsimmons, S. D. Bader, and J. N. Eckstein, Phys. Rev. Lett. 

100, 257203 (2008).

[2] K. Ueda, H. Tabata, and T. Kawai, Science 280, 1064 (1998). 

[3] K. S. Takahashi, et al., Appl. Phys. Lett. 79, 1324 (2001).

[4] B. R. K. Nanda, et al., Phys. Rev. Lett. 98, 216804 (2007).

[5] C. He, A. J. Grutter, M. Gu, N. D. Browning, Y. Takamura, 

B. J. Kirby, J. A. Borchers, J. W. Kim, M. R. Fitzsimmons, X. 

Zhai, V. V. Mehta, F. J. Wong, and Y. Suzuki, Phys. Rev. Lett. 

109, 197202 (2012).
28 NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY – NIST CENTER FOR NEUTRON RESEARCH CONDENSED MAT TER

Searching for magnetism across the metalinsulator phase transition of a doped Jeff = 1/2 

Mott insulator

C. Dhital1, T. Hogan1, X. Chen1, Z. Ren1, M. Pokharel1, W. Tian2, Z. Yamani3, C. Opeil1, J. S. Helton4, J. W. Lynn4, 

Z. Wang1

, and S. D. Wilson1

1

Boston College, Chestnut Hill, MA 02467

2

Oak Ridge National Laboratory, Oak Ridge, TN 37831

3

Chalk River Laboratories, Chalk River, Ontario K0J 1P0, Canada 

4

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

Anew frontier for materials discovery has 

recently been uncovered within a special 

class of 5d-electron compounds. These 

materials incorporate Ir4+ ions capable 

of stabilizing an effective spin one-half electronic 

ground state (Jeff = 1⁄2), where quantum fluctuations 

are maximal [1]. Electrons in this Jeff = 1/2 state 

are subject to a delicate balance between competing 

on-site Coulomb repulsion, electronic bandwidth, 

and spin-orbit coupling energy scales [1] whose 

subsequent interplay gives rise to a range of phenomena 

from unconventional superconducting states [2], to 

topologically-protected correlated electronic phases 

[3], to novel manifestations of Mott physics [4]. In 

particular, the search has begun for new electronic 

phases emergent once the insulating Jeff = 1/2 parent 

state in these 5d iridates is destabilized. In this 

highlight, we detail our recent neutron scattering-based 

exploration of the magnetic properties in a member of 

these new Jeff = 1/2 Mott insulating materials, Sr3Ir2O7

(Sr-327), as it is driven from an insulator into a metal 

via carrier doping.

Sr3Ir2O7 is the bilayer member of the RuddelsdenPopper iridate series (Fig. 1) and is known to possess a 

dramatically reduced charge gap, which rests very close 

to the metal-insulator boundary. Undoped, Sr-327 is a 

semiconducting two-sublattice antiferromagnet whose 

moments orient along the c-axis. One way of driving 

Sr-327 from an insulator into a metal is by gradually 

replacing Ir4+ (5d5) ions with Ru4+ (4d4) ions thereby 

introducing holes into the system and reducing the 

spin-orbit coupling necessary to stabilize the Jeff ground 

state. Upon replacing ≈ 35 % of Ir4+ atoms with Ru4+, 

charge transport shows that the system becomes a metal 

[6], but transport measurements cannot reveal the fate 

of the parent magnetic phase once the system enters the 

metallic regime.

O

Ir/Ru

Sr

a

b

G-type, m || c

a

b

a

b

a

b

a

b

a

b

c

b

(a) (b) (a) (b)

O

Ir/Ru

Sr

c

b

a

b

a

b

a

b

a

b

a

b

a

b

FIGURE 1: (a) Crystal structure of Sr3Ir2O7. Each (Ir/Ru) ion is surrounded 

by an octahedron of oxygen atoms. The fundamental building blocks of the 

system are IrO2 planes grouped into bilayers and separated by the A-site Sr 

atoms. Oxygen octahedra are rotated by ± 10 degrees within the ab-plane. 

(b) Magnetic structure of Sr-327 with moments pointing along the c-axis and 

antiferromagnetically coupled both within the ab-plane and between bilayers.

Our recent neutron scattering work studying the 

evolution of magnetic order in this Ru-doped Sr-327 

system has uncovered that, contrary to the picture 

painted by bulk magnetization and charge transport, 

an unexpected long-range itinerant, antiferromagnetic 

order survives deep into the metallic phase (Fig. 2) [6]. 

The persistence of magnetic order across the metalinsulator transition (MIT) calls into doubt competing 

theories that model this system as a magnetic band 

insulator. Instead, the mechanism for charge gap 

formation is likely tied to the proposed Jeff = 1/2 Mott 

mechanism along with a high temperature structural 

distortion we recently discovered.
2013 ACCOMPLISHMENTS AND OPPORTUNITIES 29CONDENSED MAT TER

In using the combined power of a position-sensitive 

detector and 3He-neutron polarization, we were 

also able to unambiguously separate magnetic and 

nonmagnetic scattering arising at the same scattering 

angles in the undoped Sr-327 compound and to 

identify structural superlattice peaks (Fig. 3) that 

violate the nominal Bbcb space group of this system 

[5]. This high temperature structural distortion is 

suggestive of a tilting of the oxygen octahedra into 

the ab-plane, and it raises questions regarding the 

distortion’s role in the charge gap formation of this 

class of materials. Future studies on doped samples on 

BT-7 will continue to explore the relationship between 

this distortion and the electronic ground state of this 

system. 

FIGURE 2: Electronic phase diagram of Sr3(Ir1-xRux)2O7. Symbols denote 

the boundaries between canted antiferromagnetic-insulating (CAF-I), 

antiferromagnetic-metallic (AF-M), paramagnetic-insulating (PM-I), and 

paramagnetic-metallic (PM-M) phases. Triangles and squares denote the 

results of bulk transport and magnetization measurements, respectively, while 

circles show neutron scattering results determining the onset temperatures of 

long-range antiferromagnetic order. 

FIGURE 3: Spin-flip (SF) and non-spin-flip (NSF) polarized neutron scattering 

data collected on the BT-7 triple-axis spectrometer. Data were collected 

at 300 K with the magnetic guide field oriented parallel to the scattering 

wave vector. The Bragg peak appears only in the non-spin-flip channel, 

demonstrating the structural origin of the superlattice and the violation of the 

Bbcb space group. Uncertaintes on the data are one standard deviation.

Through combined unpolarized and polarized neutron 

scattering investigations of the properties of the holedoped Jeff = 1/2 system Sr3(Ir1-xRux)2O7, we were 

able to show that antiferromagnetism survives into 

the metallic regime once the Jeff = 1/2 Mott phase is 

quenched. This emergent, itinerant magnetic phase 

arises from the delicate interplay between Ru4+ S = 1 

ions and the residual correlations of the Jeff= 1/2 Mott 

phase, and presents a new system for probing the 

magnetic interactions inherent to this 5d Mott phase. 

We also uncovered a surprising high temperature 

structural distortion in the undoped parent material 

Sr3Ir2O7 that may be related to the mechanism 

responsible for the insulating phase. Together, our 

neutron results uncover a complex picture of both 

magnetic and structural phase behavior within a doped 

Jeff = 1/2 insulator and suggest that electron-electron 

correlation effects play an essential role in governing 

the phase behavior in this class of 5d-electron materials.

References

[1] B. J. Kim, H. Ohsumi, T. Komesu, S. Sakai, T. Morita, 

H. Takagi, T. Arima, Science 323, 1329 (2009).

[2] F. Wang, T. Senthil, Phys. Rev. Lett. 106, 136402 

(2011).

[3] D. Pesin, L. Balents, Nature Physics 6, 376 (2010).

[4] B. J. Kim, H. Jin, S. J. Moon, J.-Y. Kim, B.-G. Park, C. 

S. Leem, Jaejun Yu, T.W. Noh, C. Kim, S.-J. Oh, J.-H. 

Park, V. Durairaj, G. Cao, E. Rotenberg, Phys. Rev. Lett. 

101, 076402 (2008).

[5] H. Matsuhata, I. Nagaia, Y. Yoshida, S. Hara, S. Ikeda, 

N. Shirakawa, J. Solid State Chem. 177, 3776 (2004).

[6] C. Dhital, T. Hogan, X. Chen, Z. Ren, M. Pokharel, W. 

Tian, Z. Yamani, C. Opeil, J. S. Helton, J. W. Lynn, Z. 

Wang, S. D. Wilson, Phys. Rev. Lett. (in review).
30 NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY – NIST CENTER FOR NEUTRON RESEARCH CONDENSED MAT TER

Frozen spin ice correlations in the ground 

state of the pyrochlore magnet Tb2Ti2O7

K. Fritsch1, E. Kermarrec1, K. A. Ross1,2,3, Y. Qiu3, J. R. D. Copley3, H. A. Dabkowska4, and B. D. Gaulin1,4,5

1

 Department of Physics and Astronomy, McMaster University, Hamilton, ON, L8S 4M1, Canada

2

 Institute for Quantum Matter and Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218

3

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

4

 Brockhouse Institute for Materials Research, McMaster University, Hamilton, ON, L8S 4M1, Canada

5

 Canadian Institute for Advanced Research, Toronto, ON, M5G 1Z8 Canada

Geometrically-frustrated magnetism has been fertile 

ground for exotic magnetic ground states in new 

magnetic materials, leading to spin glass, spin 

liquid and spin ice states at low temperatures, 

in contrast to conventional long range order found in most 

magnetic materials. Such materials are often comprised of 

magnetic moments decorating a network of interconnected 

triangles and tetrahedra, and the pair-wise interactions 

between the magnetic moments are incompatible with a 

simple ordered state on this network. Cubic pyrochlore 

titanate magnets, with the chemical composition of A2Ti2O7, 

where the A site is occupied by a magnetic rare earth ion, 

can be described in these terms. This family of materials has 

been widely explored by scientists interested in geometrical 

frustration, as many such magnets exist with varying 

properties, and they can be grown as large single crystals.

Tb2Ti2O7 (TTO) is one such cubic pyrochlore 

antiferromagnet, with magnetic Tb3+ ions decorating a 

network of corner-sharing tetrahedra. Remarkably, even 

though its exotic ground state has been debated for almost 

15 years, it has very recently been the topic of significant 

experimental research interest [1-3]. Our theoretical 

understanding of the interactions in TTO, based on classical 

Ising-like Tb3+ spins [4], originally suggested a magnetically 

ordered state below ≈ 1 K. However, early muon spin 

resonance and neutron scattering experiments on this 

material showed no evidence for long range order down 

to 50 mK [5]. Over time, this motivated two theoretical 

scenarios to account for the apparently disordered ground 

state in TTO: a quantum spin ice scenario [6] and a nonmagnetic singlet ground state [7].

Our recent neutron scattering measurements [2] on a single 

crystal of TTO, using the DCS beam line with a dilution 

refrigerator and 10 T magnet, reveal short range, static 

spin correlations developing below T ≈ 275 mK with a 

(1⁄2,1⁄2,1⁄2) ordering wave vector (Fig. 1a), and a concomitant 

opening of a spin gap across most of the Brillouin zone 

(Fig. 2). The diffuse elastic scattering observed at (1⁄2,1⁄2,1⁄2) 

positions in reciprocal space and its corresponding real 

space spin arrangement can be modeled as a short range 

antiferromagnetically ordered spin ice (Fig. 1b), in which 

spins obey a variant of the 2-in 2-out ice rules in each unit 

cell, and flip directions between adjacent cells (Fig. 1c, d). 

Spin ice itself is a six-fold degenerate arrangement of spins on 

a single tetrahedron. It leads to a macroscopically-degenerate 

disordered state which supports emergent electrodynamics, 

with diffusing magnetic monopoles as its elementary 

excitations [8].

FIGURE 1: Comparison of the measured elastic diffuse scattering in the 

(H,H,L) plane of Tb2Ti2O7 at 70 mK and H = 0 T (panel a) to the calculated S(Q) 

(panel b). The spin arrangement between neighboring conventional unit cells 

is shown as a projection onto the xy-plane in panel c). The ordered 2-in 2-out 

spin configuration in a single unit cell is shown in panel d), and this pattern 

is reversed in the neighboring cells (black vs. grey arrows in panel c) to form 

“(1⁄2,1⁄2,1⁄2) ordered spin ice”. The spins are tilted from their local [1,1,1] axes by 

12 degrees. 

Recently, ac susceptibility measurements at very low 

temperature and under a magnetic field applied along [1,1,1] 

were performed by Yin et al.[9]. They uncover a new H-T

phase diagram, with the existence of a crossover at T ≈ 0 

and μ0H ≈ 0.07 T between two quantum phases. We used 

inelastic neutron scattering to follow the evolution of the spin 

dynamics under magnetic fields as a related phase boundary 

is crossed (one pertaining to the application of a [1,-1,0] 

magnetic field, Fig. 3). For low fields and temperatures, 
2013 ACCOMPLISHMENTS AND OPPORTUNITIES 31CONDENSED MAT TER

the susceptibility of TTO is isotropic, and little directional 

dependence of the field is expected. As the magnetic field 

is increased, the diffuse scattering at the (1⁄2,1⁄2,1⁄2) positions 

gets suppressed substantially, while there is a strong buildup in intensity at the structurally forbidden 002 peak. 

The application of a small magnetic field of 0.075 T along 

[1, -1, 0] is found to destroy the antiferromagnetic short 

range ordered spin ice state previously evidenced in zero 

field (Fig. 3c), in agreement with the susceptibility data of 

Yin et al. A further feature in the elastic scattering maps 

are weak rods of scattering along the [0,0,L] and [1,1,1] 

directions that have been identified as evidence for significant 

anisotropic exchange in TTO, consistent with observations 

in other pyrochlore titanates such as Yb2Ti2O7 [10] or 

Er2Ti2O7 [11].

FIGURE 2: High-resolution neutron scattering data of Tb2Ti2O7 in zero field. 

Intensity vs. energy transfer of the (1⁄2,1⁄2,1⁄2) positions averaged over two 

peaks as a function of temperature. Note the logarithmic intensity scale. The 

Q-integration range (H = [+/-0.3 to +/-0.7], L = [1.2 to 1.8] r.l.u.) is shown in the 

inset by the two black squares. Error bars represent one standard deviation.

FIGURE 3: Elastic neutron scattering data within the (H,H,L) plane of Tb2Ti2O7

at T = 80 mK for different values of applied magnetic field (H || [1,-1,0]). The 

energy is integrated from -0.1 < E (meV) < 0.1. Panels a) through e) show the 

evolution of the elastic scattering for an applied magnetic field of 0 T, 0.05 T, 

0.075 T, 0.1 T and 0.2 T, respectively. Panel f) shows the Q-dependence of the 

elastic scattering along the [1,1,1] direction cutting through the (0,0,2) Bragg 

position as indicated by the yellow arrow in panel e). The (1⁄2,1⁄2,1⁄2) peaks vanish 

around μ0H ≈ 0.075 T (panel c)).

This set of recent neutron scattering measurements focused 

on the identification of the ground-state of TTO in zero 

and moderate magnetic fields. It notably supports the 

quantum spin ice picture to explain its low temperature 

properties - a frozen variant of spin ice is clearly observed 

at low temperatures. Diffuse scattering near the quantum 

critical point will place an important constraint on any 

theory wishing to describe this transition. The origin of the 

short range frozen state itself remains mysterious. Whether 

the presence of weak disorder, perhaps in the form of extra 

magnetic Tb3+ ions as suggested by Taniguchi et al. [3], is 

responsible for the ordering, or on the contrary is preventing 

the correlation length from diverging, is one of the key 

questions to address in the future. 

References

[1] for example: S. Petit et al., Phys. Rev. B 86, 174403 

(2012), T. Fennell et al., Phys. Rev. Lett. 109, 017201 

(2012).

[2] K. Fritsch et al., Phys. Rev. B 87, 094410 (2013).

[3] T. Taniguchi et al., Phys. Rev. B 87, 060408(R) (2013).

[4] M. J. P. Gingras et al., Phys. Rev. B 62, 6496 (2000).

[5] J. S. Gardner et al., Phys. Rev. Lett. 82, 1012 (1999); 

J. S. Gardner et al., Phys. Rev. B 68, 180401 (2003).

[6] H. R. Molavian et al., Phys. Rev. Lett. 98, 157204 

(2007); H. R. Molavian et al., arXiv:0912.2957v1 

(2009).

[7] P. Bonville et al., Phys. Rev. B 84, 184409 (2011).

[8] C. Castelnovo et al., Annu. Rev. Condens. Matter Phys. 

3, 35 (2012).

[9] L. Yin et al., Phys. Rev. Lett. 110, 137201 (2013).

[10] K. A. Ross et al., Phys. Rev. X 1, 021002 (2011).

[11] L. Savary et al., Phys. Rev. Lett. 109, 167201 (2012).
32 NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY – NIST CENTER FOR NEUTRON RESEARCH ENGINEERING

Stresses in a test artifact produced by additive 

manufacturing

T. Gnäupel-Herold1, J. Slotwinski2, and S. Moylan2

1

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

2

Intelligent Systems Division, Engineering Laboratory, National Institute of Standards and Technology, Gaithersburg MD 20899

Additive Manufacturing (AM) is a term to describe 

processes for fabricating parts layer-by-layer directly 

from a digital 3D model. AM is a technology at the 

beginning of its arc, and many parameters affecting 

performance-relevant mechanical properties have yet to be 

explored. In this work, we analyze the residual stresses in a test 

artifact made of a high-strength stainless steel with respect to 

effects of size, dimensions and aspect ratios of the structures 

in the artifact. In order to allow further processing of the 

undisturbed AM-specimen, neutron diffraction was used to 

evaluate non-destructively the three-dimensional distribution of 

stress fields.

AM has excellent prospects for producing high-value parts 

that are individually customized and complex in shape due to 

the lack of topological constraints. For example, there is no 

principal obstacle for producing a seamless, hollow sphere, and 

in a time comparable to conventional milling methods that 

still require joining of separately made parts. The capabilities 

of AM are extraordinary but the technology faces a number of 

challenges on its way to broader dissemination, including a lack 

of data and standards for mechanical properties. One of the 

central questions surrounding the process is the fidelity between 

the digital model and part metrics. This is also where residual 

stresses play a decisive role in the sense that stresses can and do 

create substantial distortions and deviations from the intended 

shape that can render the AM-produced part useless (Fig. 1).

FIGURE 1: Self-bending of a cobalt-chromium AM-sample as demonstrated by 

a 0.2 mm gap between ruler (top) and sample.

This is of particular importance for metal-based AM-built parts 

for use in applications such as automotive engines, aircraft 

assemblies and medical implants where the desired functionality 

dictates complex shapes and high strength, with the latter almost 

invariably implying high residual stresses. The implication 

of high residual stresses is rooted in the powder bed fusion 

(PBF) process most commonly used in metal-based additive 

manufacturing. The process is shown schematically in Fig. 2. 

FIGURE 2: Schematic of the powder bed fusion process. A point heat source 

provided by a 400 W Yb-fiber laser sinters a region of a powder bed. A layer is 

built by moving the point (100 μm to 500 μm diameter) according to the digital 

model using an optical deflection (mirror) and focusing system (f-q lens). After 

completion of the layer, a recoater spreads a new powder layer (≈ 0.02 mm) 

over the built structure that is then lowered by that thickness to keep the focal 

range constant. The process is repeated.

The layer-by-layer “build” occurs through moving (“scanning”) 

the laser focus within the build-plane whereby neighboring 

scan lines fuse together by a slight overlap of the laser focus. 

By thermally quenching small, hot zones where sintering of 

particles occurs (≈ 1700 K) on top of a structure that is at a 

much lower temperature (< 400 K) quenching strains arise that 

are only partially permanent (plastic), with a small fraction of 

elastic strains that give rise to residual stresses. However, this 

represents only a qualitative understanding, with the actual 

three-dimensional distribution of residual stresses depending on 

structure geometry and on machine-dependent parameters such 

as scan speed, focal diameter and laser power.

The AM machine was operated in a preset that distinguished 

between the so called “skin” mode and “core” mode. The skin 

mode featured a smaller laser focus diameter and closer scan 

lines within a range of ≈ 0.7 mm from any one of the six 

surfaces of the parallelepiped structures including the bottom 

surface fused to the build-plate (Fig. 3). This “skin” zone receives 

a higher input of thermal energy with the goal of reducing 
2013 ACCOMPLISHMENTS AND OPPORTUNITIES 33ENGINEERING

porosity and increasing strength. As a consequence, structures 

with different aspect ratios and dimensions several times that of 

the “skin” thickness will exhibit different stress fields, depending 

on the relative volumes of “core” and “skin”. In order to assess 

the influence of geometry and size on residual stresses several 

structures fused to a build-plate were investigated, and two 

different types of fusing the structures to the build plate were 

considered. The inset in Fig. 3, top right, shows one bottom 

surface (after cutting) with a support structure (blue dot) 

consisting of 0.1 mm thick walls arranged in a 1 mm by 1 mm 

pattern with 1 mm height. All structures but one (blue dot) 

on the actual sample were built with such a support structure. 

The purpose of the support structure is to allow easier removal 

after the build, and to reduce residual stresses through thermally 

insulating the structure from the build-plate during the build.

FIGURE 3: Test artifact used in the neutron diffraction stress measurements. 

Blue indicates a build that is fused directly to the build-plate (no support 

structure – red circle).

As shown in Fig. 4, this expectation of stress reduction is 

justified but the effect decreases as the distance to the buildplate increases (vertical scan). More notably, the stresses on 

the surface reach about 450 MPa – nearly 50 % of the bulk 

yield strength – which is high enough to raise concerns about 

fatigue performance.

A more detailed three dimensional analysis of the residual 

stresses is shown in Fig. 5. Three structures with very different 

aspect ratios of thickness to height ranging from 2:10 and 5:10 

were investigated with respect to stresses normal to the buildplate. The “blade” (2:10) is dominated by the “skin” mode and 

it has the least variation in terms of stress. Similar near-surface 

stresses are found in the structure with higher thickness (5:10). 

However, this structure also has a distinct “core” mode region, 

and higher stress gradients are present as indicated by the high 

compressive stresses in the interior (2.5 mm from surface). 

In other words, within a distance of approximately 2 mm the 

stresses transition from ≈ +200 MPa near-surface tensile stresses 

(“skin”) to ≈ -200 MPa compressive stress (“core”) or more. 

Another notable feature of the residual stresses is that structural 

symmetry does not necessarily imply stress symmetry.

FIGURE 4: Residual stresses in “builds” with and without support structures 

(buffer). The color codes in the inset picture are the same as in the graphs.

In this ongoing project, many of the data generated are first-inkind, and particularly the correlations between many process 

parameters (skin/core mode) and part properties such as stresses 

are not yet known. The stresses found here are unfavorable from 

a mechanical point of view because near surface tensile stresses 

promote cracking. A post-build treatment such as shot-peening 

is generally necessary to improve upon these properties, and it is 

intended to study the changes in stresses after shot-peening.

FIGURE 5: Stress maps (9x9 resolution) at various depths from the front 

surface. The arrows indicate the direction of the stress.
34 NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY – NIST CENTER FOR NEUTRON RESEARCH FACILIT Y DEVELOPMENT

TOF measurements at neutron guide NG-Bu to 

characterize the source spectrum

J. C. Cook1, J. Barker1, C. Gagnon1,2, R. Ibberson1,2, R. Lindstrom1, D. A. Neumann1, J. M Rowe1, and 

R. E. Williams1

1

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

2

University of Maryland, College Park, MD 20742

The cold neutron source of the NBSR research 

reactor at the NCNR produces a spectrum of 

especially slow-moving neutrons. These low-energy 

neutrons have particularly desirable properties 

for probing matter at the atomic level. Just as atoms in a 

gas slow down when cooled, so do neutrons when they 

interact with a cold material, giving up some of their energy 

to the material. The slowing-down material, which must 

exhibit good neutron scattering properties with low neutron 

absorption, is referred to as a moderator. In general, the 

lower the temperature of the moderator, the lower is the 

average energy of the neutrons that emerge. In the case of 

the NBSR, the cold source moderator is liquefied hydrogen 

(LH2) at atmospheric pressure at a temperature of about 

-253 °C, or 20 K. Knowing the cold neutron spectrum is a 

major asset to instrument development, and understanding 

or being able to confidently and reliably predict the spectrum 

is paramount for cold neutron source development. However, 

this seemingly fundamental quantity is surprisingly elusive. 

Unfortunately, direct measurement of the cold source 

spectrum by inserting a suitable probe in proximity of the 

functioning cold source is not feasible. An alternative is to 

measure the spectrum at the end of a cold neutron guide 

and correct for the transmission function of the guide. The 

neutron guide itself is a highly polished glass tube with special 

reflective interior coatings, used to concentrate the neutrons 

into beams and conduct them efficiently far from the 

source. As such, the neutron guide can alter the transmitted 

neutron spectrum in a complex way meaning that the guide 

transmission function must be simulated.

The temporary vacancy at the end of the newly-installed 

neutron guide NG-Bu, prior to installation of a SANS 

instrument, provided a rare opportunity to perform this 

measurement using the neutron time-of-flight (TOF) 

technique, Fig. 1. The particular properties of the NG-Bu 

guide, together with careful design of the measurement 

apparatus, allowed us to significantly improve upon 

a previous measurement from the mid-1990s. The 

aforementioned measurement was performed on an unfiltered 

straight guide (NG-1) with the first generation (Unit 1) 

liquid hydrogen cold source, but was subject to appreciable 

uncertainty. The situation was not improved by the fact 

that the second generation (Unit 2) cold source spectrum 

(previously unmeasured) had to be inferred from the Unit 

1 measurement, via measured Unit 2/Unit 1 gain curves, 

introducing another layer of uncertainty. 

FIGURE 1: A schematic layout of the TOF apparatus.

In addition to providing an accurate basis for instrument 

simulations, this measurement was motivated by the desire 

to understand more fully the physics of the liquid hydrogen 

cold source when the reactor is operating at full power. Even 

though the cold source at the NBSR operates at atmospheric 

pressure, the liquid hydrogen at 20 K is not a straightforward cryogen by virtue of the spin of the protons in the 

hydrogen molecule. In a low-radiation environment, freshly 

liquefied hydrogen (such as we have prior to most beginningof-cycle reactor startups) consists of a 75 % mole fraction 

of molecules in which both proton spins are parallel (ortho) 

and 25 % mole fraction of para (spins antiparallel). This 

ratio reflects the statistical occupancy of angular momentum 

states in “normal hydrogen” – an example of which is 

room-temperature hydrogen. Once liquefied, the hydrogen 

converts slowly towards the para ground state – a process 

that may be catalyzed – although 100 % mole fraction para 

is rarely achieved. However, in a high-radiation environment 

a different, but hard to quantify, ortho-para equilibrium is 

established. When trying to model the cold source spectrum 

this presents a problem because the scattering properties of 

ortho and para hydrogen are quite different in the energy 
2013 ACCOMPLISHMENTS AND OPPORTUNITIES 35FACILIT Y DEVELOPMENT

region of interest. Specifically, the scattering cross-section of 

para hydrogen is much lower than that of ortho hydrogen for 

neutron energies below about 15 meV (wavelengths greater 

than about 2.3 Å). Thus, a simulation of the cold source 

assuming an incorrect ortho:para ratio results in an incorrect 

spectrum. Furthermore, there are some disagreements 

between sources of ortho and para hydrogen scattering data 

used in transport codes, which leads to further uncertainty.

The neutron wavelength calibration was performed by 

measuring Bragg edges from a polycrystalline beryllium 

crystal and a polycrystalline graphite crystal. The absolute 

intensity normalization was provided by a gold foil activation 

measurement of the thermal-equivalent fluence rate. The 

three TOF measurements, each at different stages of a reactor 

cycle, yielded evidence that the spectrum below about 3 Å 

might change slightly during the cycle, but the cold 

neutron spectra revealed few differences. Fig. 2(a) shows 

the results of the three independent measurements (at 

20 MW). The “fuzziness” on the three sets of curves indicates 

a credible distribution of results, obtained by running 

multiple simulations of the NG-Bu guide with supermirror 

reflectivities, substrate waviness, and element misalignments 

adjusted randomly within their analyzed distributions. The 

blue curve in Fig. 2(b) represents the mean of these curves, 

which is henceforth adopted as the standard for future 

simulations. The shortest wavelength part of this model 

(which is relatively insensitive to variations in the ortho:para 

hydrogen ratio) is appended from an MCNP [1] simulation 

of the cold source cavity brightness, assuming a 65:35 

ortho:para mole ratio, with (calculated) scattering kernels 

originating from Los Alamos National Laboratory. This 

MCNP simulation, extended into the cold neutron region, is 

indicated by the circular black symbols for comparison with 

the measurements.

FIGURE 2: (a) Estimated Unit 2 LH2 cold source brightness resulting from three 

independent TOF measurements. For each measurement, 20 superimposed 

curves are shown, corresponding to 20 independent simulations of the 

neutron guide transmission. For each simulation a unique guide configuration 

was generated by randomly selecting the reflectivity, substrate waviness, and 

element misalignments within their estimated distributions. The distribution 

of the curves is therefore characteristic of the spread in results due to the 

simulation step of the brightness evaluation. (b) An MCNP simulation 

assuming a 65:35 ortho:para ratio using LANL scattering kernels (black circles) 

is compared against the mean brightness function from the curves in (a).

In total, three independent measurements were performed, 

including an attempt to witness spectral changes due to the 

increase of ortho content during the initial reactor power 

ramp and hold at 20 MW. The latter required extraordinary 

coordination with various teams. The hydrogen was liquefied 

many days prior to startup (to maximize the initial para 

concentration) and measurements were taken quickly as 

power was increased. In the end, measurements yielded little 

evidence of a significant change in the neutron spectrum 

suggesting that either equilibrium is established within 

minutes of startup or that the initial para concentration is 

lower than expected.

In conclusion, we have performed the most accurate 

measurement-based estimate of the NBSR Unit 2 liquid 

hydrogen cold source brightness to date. The data quality 

was sufficient to yield reliable source brightness estimates 

extending to neutron wavelengths exceeding 60 Å (neutron 

speeds below 65 m/s). A comparison of the measurement 

with simulations using the particle transport code MCNP 

and hydrogen scattering data originating from ENDF/B-VII 

(endf70a and endf70sab libraries) is consistent with a steadystate hydrogen distribution of (50 to 75) % mole fraction in 

the ortho state. These measurements eliminate uncertainties 

from previous measurements of the cold source brightness 

and will allow for improved design choices in future cold 

source development. More details of these measurements will 

appear in a forthcoming publication.

References

[1] MCNP–A General Monte Carlo N-Particle Transport 

Code, Version 5, X-5 Monte Carlo Team, Diagnostics 

Applications Group, Los Alamos National Laboratory.
36 NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY – NIST CENTER FOR NEUTRON RESEARCH GEOLOGY

Nano-pore condensation of methane in shales

A. P. R. Eberle1, H. E. King1, G. Rother2, D. J. Wesolowski2, C. C. Walters1, and C. E. Kliewer1

1

ExxonMobil Research and Engineering Company, Annandale, NJ 08801

2

Oak Ridge National Laboratory, Oak Ridge, TN 37831

I

n the last decade, natural gas produced from shales has 

grown to become a major factor in the U.S. energy 

supply. This boom is largely the result of improved 

extraction methods and a better understanding of the 

porous nature of mature organic matter. The production 

rates of wells within the same geologic formation can 

vary significantly. Opportunities to optimize well number 

and placement and completion practices require a fuller 

understanding of the physics of gas encapsulation and flow 

in shale. 

Shales are sedimentary rocks consisting of both organic 

and inorganic matter. While it is well established that the 

productivity of shale is a function of both gas storage and 

transport, the pore architecture in most high-maturity 

organic-rich shales is poorly understood. For instance, 

sorption measurements and microscopy suggest the majority 

of the porosity resides within organic matter [1,2]. This is 

in contrast to coarser grained sedimentary rocks where the 

pores form within a mostly inorganic framework and the 

pore-rock fabric interface is well described as a continuum 

of pore sizes spanning a range from mm to nm, following an 

approximately power-law size distribution [3]. 

Small-angle neutron scattering (SANS) offers unique 

advantages over other scattering techniques such as light and 

x-ray in the measurements reported herein as i) neutrons 

are highly penetrating, ii) neutrons interact with the atomic 

nucleus and lend to isotope labeling, and iii) the neutron 

scattering length density of the inorganic components of 

the matrix are similar, and as a result, the majority of the 

scattering comes from the pores. We use SANS to study 

the pore selectivity to light hydrocarbon condensation. We 

report on experimental measurements of shale samples under 

vacuum and pressurized with both deuterium and methane 

[4]. At pressures up to 34.5 MPa we find that methane 

condenses into nano-sized pores located within the organic 

phase of the matrix.

FIGURE 1: a) SANS scattering intensity from a shale sample in both vacuum 

and at 34.5 MPa of deuterium (D2). b) Expanded SANS from the region outlined 

by the box in (a). c) Average scattering length density of the matrix calculated 

from Eq. (1).

Shale slabs were cut parallel to the bedding plane with 

thickness < 0.4 mm to minimize multiple scattering. SANS 

measurements were performed using the NIST high pressure 

de-mountable cells under vacuum and pressurized with 

various gases. Fig. 1 (a) displays the scattering intensity, 

representative of all samples measured, in vacuum and 

at 34.5 MPa with D2. Deuterium, thermodynamically 

similar to hydrogen, has a relatively small kinetic diameter, 

d = 0.289 nm, and can be treated as an ideal gas over a wide 

range in temperature and pressure. We assume all the pores 

within the length scales measured with SANS ( >≈ 1 nm) 

are accessible to the gas molecules. The scattering at the 

two conditions is similar but the total intensity decreases 

for the case of deuterium, see Fig. 1 (b) an expansion of the 

box in Fig. 1 (a). This is expected as the major component 

to the scattering intensity arises from the contrast between 

the matrix and the pores, I(Q) ~ (ρmatrix – ρpore)2, where 

ρ is the scattering length density, and Q is the momentum 

transfer. The matrix ρmatrix ≈ 4 x 10-6 Å-2, and for vacuum 

and with deuterium, respectively, ρpore ≈ 0 Å-2 and 

ρpore ≈ 8.55 x 10-6 Å-2 , assuming gas density in the pore is 

equal to the bulk density calculated from the NIST Reference 

Fluid Thermodynamic and Transport Properties Database 

(REFPROP). To a first order approximation the pores can 

be represented by particulate scattering methods from a two-
2013 ACCOMPLISHMENTS AND OPPORTUNITIES 37GEOLOGY

phase system, in which case the average scattering length 

density of the matrix can be calculated from the following 

ratio, where ρvac, ρD2

, and ρm are the scattering length 

densities of the pore under vacuum, pore at pressure with 

D2 and the matrix, respectively, and Sf is the scattering 

function for the system. Fig. 1 (c) is a plot of the ρm vs. Q

calculated using Eq. (1), and we obtain an average 

ρm = 4.8 x 10-6 Å-2. This value agrees well with the estimated

scattering length density of the inorganic matrix (matrix 

composition determined from x-ray diffraction measurements,

data not shown) and is roughly twice the estimated value of 

the scattering length density of the pure organic material, 

ρorganic ≈ 2.0 x 10-6 Å-2.

 

FIGURE 2: SANS scattering intensity from a shale sample in both vacuum and 

at 34.5 MPa of methane (CD4 and CH4). The predicted scattering curve of CD4

determined using Eq. (1) with the bulk scattering length density of methane 

and the average scattering length density of the matrix.

Fig. 2 displays the predicted SANS scattering intensity using 

Eq. (1) and assuming bulk density of the deuterated methane 

within the pores, along with the experimental scattering 

from both CD4 and CH4 at 34.5 MPa. For length scales 

(L ≈ 2π/Q) L >≈ 15 nm, the predicted scattering is nearly 

identical to the experimental data but diverges at higher Q. 

This suggests a significant change in the scattering contrast, 

Δρ, as result of capillary condensation of the gas within the 

nano-pores, i.e. ρgas ≈ 2.93 x 10-6 Å-2, ρliquid ≈ 5.29 x 10-6 Å-2

(in the case of CD4). More detail can be extracted by 

considering the relative magnitude of the intensities at 

high Q, ICH4 > ICH4 > Ivacuum. Within the assumption 

that I(Q) ~ (ρmatrix – ρpore)2, and recognizing that ρCD4

and ρCH4 are quite distinct allows us to conclude that the 

major scattering contribution must arise from the fact that 

methane is selectively condensed within the organic phase. 

These results confirm without question that there is porosity 

within both the inorganic and organic phases of shales and 

the methane condenses within the nano-pores of the organic 

phase. However, we cannot rule out that the methane also 

condenses in nano-pores found in the inorganic phase.

A summary of our findings is depicted in Fig. 3. Shales 

consist of both an inorganic and organic phase. On large 

length scales O(cm) the compositional distribution is 

homogeneous but locally the two phases are separate. 

Pores exist in both phases but there are a disproportionate 

number of small pores O(nm) in the organic phase. We have 

confirmed the existence of the small pores through direct 

imaging using Helium Ion microscopy, an example can be 

seen as an inset to Fig. 3. When pressurized with methane, 

capillary condensation occurs in the small pores located 

within the organic phase. These results shed light on the 

phase behavior and interaction of light hydrocarbons in 

shales and have implications in quantifying total hydrocarbon 

capacity in shales, as well as the development of improved 

extraction methods.

FIGURE 3: Schematic of inorganic and organic phases in shale. The box 

indicates a magnification of the organic phase: (left) helium-ion image of 

nano-pores in the organic phase, (right) schematic of nano-pores under two 

conditions as inferred from SANS measurements: (right, top) vacuum, and 

(right, bottom) pressurized with methane. Blue and yellow represent liquid and 

gas phases, respectively.

References

[1] P. H. Nelson, Amer. Assoc. Petr. Geologists Bulletin 93, 

329 (2009).

[2] R. G. Loucks et al., J. Sed. Research 79, 848 (2009).

[3] A. P. Radlinski et al., Phys. Rev. Lett., 82 (15), 3078 (1999).

[4] A. P. R. Eberle et al., In preparation 2013.
38 NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY – NIST CENTER FOR NEUTRON RESEARCH SOFT MAT TER

Probing the interlamellar amorphous phase in 

semicrystalline polyolefins using vapor flow

A. G. McDermott1,2, C. R. Snyder1, R. L. Jones1,2

1

Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, MD 20899

2

nSoft, National Institute of Standards and Technology, Gaithersburg, MD 20899

The increasing popularity of shale-based sources of 

fuel, where byproducts of the extraction process 

are a cheap route to macromolecular synthesis, 

is driving a revolution in both commodity and 

high-performance polymer materials [1]. Key to this 

revolution is the development of new molecular architectures 

for polyolefin materials used to make polyethylene and 

hundreds of derivative plastics. To achieve new properties, 

materials chemists have pursued co-crystallized and 

blended structures by producing a wide array of molecular 

topologies including polyolefins with blocky main and side 

chains as well as compatibilizing side groups. While these 

strategies are thought to provide the range of properties 

necessary to meet emerging societal needs, there is a severe 

lack of direct measurements of the structure within a 

semicrystalline polymer. We report on developments of a 

new Small-Angle Neutron Scattering (SANS) method, using 

an infusion of labeled vapor into the amorphous polymer 

region to characterize structure and thermodynamics within 

semicrystalline polymers.

Semicrystalline polymers such as polyethylene often form 

sheet-like crystalline lamellae separated by amorphous 

material, termed here the “interlamellar” amorphous phase. 

“Extralamellar” amorphous regions can be found at grain 

boundaries and regions of uncrystallized material. These 

lamellar stacks may be randomly oriented (if crystallized 

without anisotropic stress), have a preferred orientation (if 

stretched or blown), or be nearly completely oriented (if 

crystallized under shear flow) (Fig. 1). 

FIGURE 1: SANS patterns from polyethylene samples with contrast enhanced 

by absorption of cyclohexane-d12 or p-xylene-d10 vapor into the interlamellar 

amorphous material. Insets are statistical representations of the corresponding 

morphologies of the lamellar stack orientation, in (left to right) an unoriented 

film, an oriented film, and a highly oriented fiber.

Key to determining mechanical, barrier and other properties 

is the precise structure of chains within the interlamellar 

amorphous region. As shown in Fig. 2, these molecules can 

enter adjacent crystalline lamellae at both, one, or neither 

end. “Tie chains” spanning the interlamellar amorphous layer 

provide a direct mechanical function analogous to crosslinks 

in a network. While methods such as differential scanning 

calorimetry and mechanical stretching can be used to extract 

some indication of the conformation, composition, and density 

of molecules in this region, the measurements are indirect and 

often do not provide the required level of information.

FIGURE 2: Semicrystalline polymer microstructure consisting of crystalline 

lamellae and interlamellar amorphous layers, (a) dry under no stress, (b) dry 

under external mechanical stress, and (c) swollen in solvent vapor. 

Measuring equilibrium swelling as a function of solvent 

vapor activity is an established method of simultaneously 

determining the polymer-solvent interaction parameter and the 

effective tie-chain molecular weight [2-4]. Bulk measurements 

of swelling and solvent uptake, however, include contributions 

from both extralamellar and interlamellar amorphous material; 

they generally must also treat the permeant and amorphous 

phase as incompressible fluids. Because tie chains so strongly 

influence the properties of semicrystalline polymers, 

measurements of swelling and solvent uptake that are 

independent of one another as well as specific to interlamellar 

amorphous material are highly desirable.

Inspired to improve these equilibrium swelling experiments 

using scattering methods, we have utilized a vapor flow 

cell [5,6] at the NG-B 10m SANS instrument at the NIST 

Center for Neutron Research (NCNR) to measure structure 

within the interlamellar amorphous regions. Critically, the 

method relies on the permeability of amorphous polymer to a 

nSoft
2013 ACCOMPLISHMENTS AND OPPORTUNITIES 39SOFT MAT TER

chosen vapor and the impermeability of the crystalline phase 

to the same vapor. Polyolefins exhibit nearly zero scattering 

contrast between crystalline and amorphous phases. But 

when deuterated gas, such as cyclohexane-d12, is allowed 

to permeate the amorphous region there is great neutron 

scattering contrast. When the swelling experiment described 

above is performed, the observed scattering peak is related 

to the long period of the lamellar structure, L. The degree 

of anisotropy of this peak is also indicative of the degree of 

orientation present, as described in Fig. 1.

In this in situ SANS swelling experiment, a melt-quenched 

sample of linear polyethylene SRM1475 [7] was equilibrated 

under cyclohexane-d12 vapor flow at several well-defined 

vapor activities. The dry long period, necessary to quantify 

the degree of swelling, was derived from an independent 

SAXS measurement. While a similar swelling experiment 

could also be carried out with SAXS, the larger contrast 

afforded using SANS independently quantified the amount 

of vapor absorbed; larger solvent vapor activities as caused 

the sample to absorb more vapor, producing larger scattering 

intensities as the peak shifted to lower wavevectors (Fig. 3). 

FIGURE 3: SANS patterns from an unoriented polyethylene film equilibrated 

under cyclohexane-d12 vapor flow at different solvent vapor activities as. A 

structure factor fit equating areas under peaks to the peak intensities of an 

ideal 1D lamellar structure yields the amorphous layer thickness.

The lamellae exhibit paracrystalline order; when distributions of 

crystal and amorphous layer thicknesses lc and la are sufficiently 

narrow, higher-order peaks are observed. The areas under 

these peaks (Fig. 3) were taken as the peak intensities of a 

corresponding ideal one-dimensional lamellar structure, which 

are determined by a structure factor arising from the relative 

thicknesses of the amorphous and crystalline layers within 

the lamellar stacks. From differential scanning calorimetry 

measurements, la,dry was known to be smaller than lc. The 

thickness of the interlamellar amorphous layer as a function of 

vapor activity was thus extracted from SANS patterns.

From Flory-Rehner swelling theory [2] adapted for onedimensional swelling [3], the interlamellar amorphous 

swelling ratio la/la,dry can be related to the solvent activity as

and an effective polymer-solvent interaction parameter χeff 

has a linear dependence as shown in Fig. 4. 

FIGURE 4: Fitting the data using the thermodynamic theory described in 

[3] yields an experimental measurement of the polymer-solvent interaction 

parameter χ and effective tie-chain molecular weight Mtc, both specific to the 

interlamellar amorphous fraction. Two points are omitted from the fit because 

samples did not reach equilibrium at the largest solvent activities.

The tie-chain molecular weight Mtc derived from the 

data in this study agrees well with literature values [3,4], 

considering that it likely depends sample history. The value 

of χ, while highly sensitive to choices in modeling and fitting 

the SANS patterns, differs from literature values derived 

from bulk measurements. Refinement of the modeling 

approach is required to reveal whether these differences are 

within measurement error or arise from variation in density 

and vapor solubility across the interlamellar amorphous 

region due to the presence of mesophases such as the rigid 

amorphous fraction. 

Combining SANS and swelling experiments provides 

a uniquely specific measurement of effective tie-chain 

molecular weight in the interlamellar amorphous 

fraction. This property largely determines the mechanical 

performance of semicrystalline polymers and is strongly 

influenced by processing conditions. This technique also 

provides information about the thermodynamic property χ, 

describing polymer-solvent energetic interactions, specific 

to the interlamellar amorphous region. This is important in 

understanding the permeability of functional materials as well 

as the effect of processing techniques such as gel spinning 

and solvent casting. Both Mtc and χ may differ from values 

previously derived from bulk measurements of swelling. 

While these SANS swelling experiments were performed on 

unoriented films, the vapor contrast-enhancement technique 

is also applicable to oriented films and fibers.

References

[1] Plastics News, June 21, (2013).

[2] P. J. Flory, J. Rehner, J. Chem. Phys. 11 (11), 521 (1943).

[3] H. R. Brown, J. Polym. Sci.: Polym. Phys. 16 (10), 1887 (1978).

[4] C. E. Rogers, V. Stannett, M. Szwarc, J. Phys. Chem. 63 (9), 

1406 (1959).

[5] M.-H. Kim and C. J. Glinka, J. Appl. Cryst. 38 (5), 734 (2005).

[6] M.-H. Kim and C. J. Glinka, Rev. Sci. Instr. 76 (11), 

113904 (2005).

[7] C. A. Hoeve, et al., Journal of Research of the NBS: A. Physics and 

Chemistry, 76A (2) 137 (1972).
40 NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY – NIST CENTER FOR NEUTRON RESEARCH SOFT MAT TER

Fibrillar structure of methylcellulose hydrogels

J. W. McAllister1, J. R. Lott1, M. Wasbrough2,3, F. S. Bates4, and T. P. Lodge1,4

1

Department of Chemistry, University of Minnesota, Minneapolis, MN 55455

2

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

3

University of Delaware, Newark, DE 19716

4

Department of Chemical Engineering & Materials Science, University of Minnesota, Minneapolis, MN 55455

Methylcellulose (MC) is a commercially 

important polymer prepared by partial and 

heterogeneous replacement of cellulose 

hydroxyl moieties with methoxyl groups. 

When the degree of substitution per anhydroglucose unit 

is intermediate (i.e., ca. 1.6 – 2.1), MC is a water-soluble 

polymer at low temperatures, and reversibly transitions to 

a turbid hydrogel at elevated temperature (Fig. 1) [1]. MC 

is categorized by the U.S. Food and Drug Administration 

as generally recognized as safe and has found use in 

a wide variety of products as thickeners or binders in 

pharmaceuticals, foods, and cosmetics as well as in building 

materials, ceramics, and cements. Despite widespread use of 

MC for nearly a century, the gel structure has been poorly 

understood. Fig. 1 shows the relationship between the 

thermogelation of MC by rheology and presence of fibrils 

by cryo-TEM. In this report, using a powerful combination 

of cryogenic transmission electron microscopy (cryo-TEM) 

and small-angle neutron scattering (SANS), we quantify fibril 

growth during MC thermogelation.

FIGURE 1: Storage (black) and loss (green) shear moduli, G' and G" respectively, 

of an aqueous 1.4 % mass fraction MC solution with M = 3.0 × 105 w g/mol upon 

heating (circles) and cooling (triangles). Measurements were collected using 

a frequency of 1.0 rad/s, 5 % strain and a heating and cooling rate of 1 °C/min. 

When G’ < G” (2 °C to 60 °C on heating, 2 °C to 30 °C on cooling), no structure is 

visible by cryo-TEM. However, when G’ > G” (60 °C to 80 °C on heating, 30 °C to 

80 °C on cooling), MC gels exhibit fibril structure of (15 ± 2) nm. All scale bars 

are 200 nm. SANS for MC gels at 70 °C of 5 different concentrations is 

shown in Fig. 2a. Scattering of the gel is noted by a break in 

intensity scaling from q -1.8 to q-4.2 at q ≈ 0.015 Å-1, for a 

more than a decade of concentrations. This is notable [2], as 

it suggests that MC gels have a structure that is independent 

of concentration between (0.09 to 2.45) % mass fraction. 

A model for the form factor of a semiflexible cylinder, first 

proposed by Pedersen et al. [3,4] was used to model the fibril 

gels at temperatures above 70 °C:

Model fits for concentrations from (0.09 to 2.45) % mass 

fraction give a uniform fibril diameter of (14 ± 1) nm, in 

excellent agreement with cryo-TEM results. If the scattering 

length density (ρcy1) of the cylinder in the model was set to 

ρMC of MC, there was a systematic overshoot of the model 

fit to the experimental data shown in Fig. 2a. This 

suggests that the fibrils of methylcellulose have a 

lower ρ than MC (expressed mathematically, 

(ρcy1 – ρD2O)

2

= x2(ρMC – ρD2O)

2

, where x is the volume 

fraction of MC contained in the fibrils) and the volume 

fraction of cylinders can be related to the volume fraction 

of MC in the cylinders by the fraction x, φcy1 = φMC/ x. 

Therefore, SANS intensity is directly proportional to the 

volume fraction of MC in the fibrils, I(q) ~ x. Using this 

relation, the fibrils of MC were found to contain (40 ± 5) % 

volume fraction polymer, with the remainder of the 

fibril comprised of solvent. 

Fig. 2b displays scattering intensity of a 1.09 % mass fraction 

solution of MC upon slow heating to the gel state at 70 °C. 

SANS and cryo-TEM suggest that MC exists primarily as 

semiflexible chains in solution at low temperatures, and the 

fibril structure develops upon heating, visible in the SANS 

by the growth of the slope break at q = 0.015 Å-1. 
2013 ACCOMPLISHMENTS AND OPPORTUNITIES 41SOFT MAT TER

At temperatures less than 40 °C, SANS can be fit to a model 

for semiflexible chains in solution: 

modified from Chatterjee et al. [5] At temperatures above 

70 °C, the semiflexible cylinder model is used with the 

appropriate ρcy1 calculated from Fig. 2(a). For intermediate 

temperatures, linear combinations of the two models can 

be used to approximate the scattering intensities, and as 

seen in Fig. 2(b), the fit is very good. To achieve the model 

fits in Fig. 2, a number of assumptions were made. At 

25 °C, the solution is assumed to have no fibrils, which is 

appropriate based upon our cryo-TEM results. At 70 °C, 

the gel is assumed to be comprised entirely of fibrils with 

no free chains. This is reasonable, based upon NMR results 

from Chatterjee et al. [5] showing a disappearance of the 

hydroxyl-water peak at 70 °C, indicating that MC molecules 

are associating very little with the surrounding solvent. Using 

this method, we are able to predict the scattering intensities 

during the entire heat-cool cycle of MC thermogelation.

FIGURE 2: (a) SANS of MC gels at 70 °C, with corresponding model fits to a 

semiflexible cylinder model assuming the SLD of the cylinders is equal to 

MC. The systematic overshoot of the model compared to the data indicates 

that fibrils in MC gels contain (40 ± 5) % volume fraction polymer with the 

remainder solvent. Intensities have been shifted for clarity of viewing. (b) 

SANS of a 1.09 % mass fraction MC solution heated from 40 °C to 70 °C, and 

model fits to linear combinations of semiflexible chains (low T) to semiflexible 

cylinders (high T).

Fig. 3 is calculated using the fraction of each model 

(semiflexible chains or semiflexible cylinders) applied to 

the fit at each temperature of the heat-cool cycle for MC. A 

“Fraction MC in fibrils” value of zero fibrils indicates that 

the semiflexible chain model was used exclusively, while 

a value of one indicates wholly the semiflexible cylinder 

model. Fig. 3 contains similar hysteresis upon heating and 

cooling to the storage modulus (G) of Fig. 1. This similarity 

strongly suggests that the growth of a fibril network is directly 

responsible for the elasticity of MC gels. 

FIGURE 3: The distribution of MC between solution and fibrils upon heating 

and cooling, calculated from an analysis of linear combination of semiflexible 

chains (solution) and semiflexible cylinders (fibrils) illustrated in Fig. 2.

We report a correlation between SANS, rheology, and 

cryo-TEM for the thermoreversible gelation of aqueous 

MC solutions. Upon heating, MC develops fibrils with 

uniform diameters of (14 ± 1) nm, which is agrees very 

well with cryo-TEM images. Using differences between the 

scattering length density of fibrils and MC, it was found that 

MC fibrils contain (40 ± 5) % volume fraction polymer, 

and approximately 60 % mass fraction solvent for MC 

concentrations between (0.09 to 2.45) % mass fraction. 

Model fits during a heat-cool cycle of MC indicate that a 

solvent-swollen fibril network is responsible for the elastic 

behavior of MC gels at elevated temperature.

References

[1] S. A. Arvidson, J. R. Lott, J. W. McAllister, J. Zhang, F. S. 

Bates, T. P. Lodge, R. L. Sammler, Y. Li, M. Brackhagen. 

Macromol. 46 (1), 300 (2013).

[2] K. Kobayashi, C. Huang, T.P. Lodge, Macromol. 32 (21),

7070 (1999).

[3] J. S. Pedersen, P. Schurtenberger. Macromol. 29 (23),

7602 (1996).

[4] W. R. Chen, P. D. Butler, L. J. Magid, Langmuir 22 (15) 

6539 (2006).

[5] T. Chatterjee, A. I. Nakatani, R. Adden, M. Brackhagen, 

D. Redwine, H Shen, Y. Li, T. Wilson, R. L. Sammler. 

Biomacromol. 13 (10), 3355 (2012).
42 NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY – NIST CENTER FOR NEUTRON RESEARCH SOFT MAT TER

Polymer chain mobility in confined polystyrene films

B. Akgun1,2,3, M. D. Dimitriou2, and S. K. Satija2

1

Bogazici University, Bebek 34342, Istanbul, Turkey

2

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

3

University of Maryland, College Park, MD 20742

Thin polymer films are widely used in cutting-edge 

technologies including semiconductor processing, 

organic electronics, protective coatings, biological 

coatings, sensors, and filtration. The final structure 

and performance of a film is largely dictated by the processing 

conditions used in the production of a film. Furthermore, 

the processing methods used to create a film are greatly 

affected by the thermal properties of the polymers that make 

up the film. As such, the glass transition temperature (or 

Tg, the temperature at which a polymer begins to flow) 

is a crucial property in determining a suitable processing 

method. However, as industry pushes to create polymers 

with greater functionality and smaller feature sizes, as well as 

thinner polymer films to cut cost, the soft matter community 

must reevaluate their conventional understanding of Tg to 

include polymers that exist in a confined geometry within the 

thin film—an environment which differs drastically from 

the bulk conditions typically used to measure Tg. Polymer 

mobility, which is inversely correlated with Tg in bulk, is 

not only easier to quantify than Tg, but better characterizes 

the behavior of the polymer within the thin film. Numerous 

studies have been dedicated to understand how Tg and 

polymer mobility change in a confined geometry; however, 

little research has been performed to determine if and how 

the relationship between Tg and mobility change when 

under confinement [1]. In this paper we investigate this 

relationship using samples where large Tg reductions have 

been observed [2] suggesting an enhanced mobility in the 

vicinity of a film surface. We leverage the unique elemental 

contrast that neutron reflectometry (NR) offers to observe 

perpendicular mobility in stacked layers of miscible polymers 

where the sample film geometry confines the polymers [3].

To measure the mobility under confinement, we 

engineered two samples of equal total thickness (Fig. 1). 

First, a 40 nm thick layer of deuterated polystyrene (dPS) 

(Mn = 525,000 g/mol) was spin coated onto a silicon wafer. 

Next for the bilayer film, a 21 nm thick layer of hydrogenated 

polystyrene (hPS), of equal molecular weight to dPS, was 

floated on top to create a 61 nm bilayer film. The trilayer 

sample was created by floating first a 11 nm thick hPS and 

then a 9 nm thick dPS. The floating technique allowed us 

to generate stacks of polymer thin films with extremely 

sharp interfaces (less than 1.5 nm RMS roughness) between 

the hPS and dPS layers. The isotopic difference between 

hydrogen in hPS and deuterium in dPS creates an enhanced 

contrast when utilizing NR, allowing us to quantify both 

the layer thickness and interface width between layers with 

sub-nanometer accuracy. This distinct isotopic difference, 

however, did not alter the polymer mobility due to the fact 

that the two polymers are fully miscible at 525,000 g/mol. 

By using the bilayer and trilayer samples, we could monitor 

the dPS/hPS interface at three distinct depths from the air/

film (free) surface: 9 nm (9TL), 20 nm (20TL), and 21 nm 

(21BL). Monitoring the interfaces as they broadened upon 

annealing enabled us to quantify perpendicular polymer 

mobility in a confined geometry and how it compares to 

polymer mobility in bulk.

FIGURE 1: Schematic of the arrangement of bilayer and trilayer samples used 

in this work to characterize interfacial broadening of the three interfaces 21BL, 

9TL, and 20TL.

The films were characterized using NR, generating a 

reflection profile as a function of momentum transfer vector 

perpendicular to the surface, Q. Next, both films underwent 

a set of equal annealing histories where the temperature was 

increased and reflectivity profiles were measured after each 

annealing step. Fig. 2a depicts the reflectivity profiles of the 

trilayer film after annealing. Each reflectivity profile was 

then fit to obtain a corresponding scattering length density 

depth profile (Fig. 2b) allowing us to determine the elemental 

composition and thickness of each layer, as well as the 

interfacial roughness between dPS and hPS layers. The rate at 

which the interface broadened was indicative of the polymer 

mobility due to interdiffusion between the miscible layers.

To negate differences in sample preparation the calculated 

interfacial roughness of each annealing step was normalized 

to the initial roughness prior to annealing. The normalized 

roughness values were then collapsed onto a universal curve 

using the time-temperature superposition principle (Fig. 3a). 

At ≈ 90 o

C to ≈ 95 oC the chains become mobile and 

the broadening of all three interfaces progress at the same rate 

suggesting that polymer mobility, in the direction 
2013 ACCOMPLISHMENTS AND OPPORTUNITIES 43SOFT MAT TER

perpendicular to the film surface, is the same at both 9 nm 

and 20 nm depths for PS films. This result is notable and 

either contradicts earlier work stating that Tg within these 

depths is not constant [2] or indicates that the relationship 

between Tg and polymer mobility cannot be described as 

simply inversely correlated, as conventionally assumed.

FIGURE 2: a) Evolution of trilayer reflectivity as a function of momentum 

transfer vector perpendicular to the surface, Q, taken intermittently during the 

anneal history. b) The scattering length density depth profile as determined by 

the best fit of the reflectivity.

80

60

40

20

0

Normalized RMS roughness (Å)

10-7 10-5 10-3 10-1 101 103

85 90 95 100 105 110 115 120

 21BL

 9TL

 20TL

Annealing temperature (°C)

a

Reduced annealing time

FIGURE 3: a) The normalized RMS roughness at each annealing step for 

each interface is collapsed onto a universal curve using time-temperature 

superposition showing the universality of the evolution of interfacial 

roughness. Error bars on data are statistical and are one standard deviation. 

b) The RMS broadening of 21BL compared to that of a bulk interface (80BL) at 

120 °C shows the increased mobility in the confined films.

To confirm that the system displays a correlation between 

the Tg and polymer mobility, we compared the interfacial 

broadening rate of 21BL with that of a bulk system at 120 °C 

(Fig. 3b). To do this, we generated an additional bilayer 

sample using the same preparation methods as described 

earlier but significantly increased the film thickness to avoid 

polymer confinement effects. Both the dPS and hPS layers 

were 80 nm thick, resulting in a 160 nm thick bilayer film 

and an interface 80 nm from the film surface (80BL), so that 

the film displays bulk polymer properties. Fig. 3b shows 

the distinctly higher interfacial broadening rate for 21BL 

relative to 80BL indicating that we in fact observe increased 

polymer mobility in the confined thin film bilayer interface as 

compared to the bulk sample.

The unique scattering contrast that neutrons have to offer 

has allowed us to probe the interactions at an interface of 

two analogous polymer layers. This study addressed two 

major points. First, it showed that when compared to bulk 

conditions, confined polymer thin films show increased 

amounts of mobility, in agreement with previous research 

that found Tg reduction under confinement. Second, the 

unique sample design allowed us to determine that there is 

no measureable difference in polymer mobility in confined, 

thin films at 9 nm and 20 nm depths. This finding suggests 

that either Tg and polymer mobility are not correlated, or 

that there is no gradient in Tg in polymer thin films between 

9 nm and 20 nm from the air/polymer surface. 

References

[1] J. A. Forrest, K. Dalnoki-Veress, Adv. Colloid Interface Sci., 94, 

167 (2001).

[2] C. J. Ellison, J. M. Torkelson, Nat. Mater., 2 (10), 695 (2003).

[3] B. Akgun, M. D. Dimitriou, S. K. Satija, submitted.
44 NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY – NIST CENTER FOR NEUTRON RESEARCH SOFT MAT TER

Small-angle neutron scattering reveals the size and 

shape of bottlebrush polymers in solution

S. L. Pesek1, X. Li1, B. Hammouda2, K. Hong3, and R. Verduzco1

1

Rice University, Houston, TX 77251

2

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

3

Oak Ridge National Laboratory, Oak Ridge TN 37831

P

olymeric nanoparticles are a versatile class of materials 

currently being studied for a wide-range of applications 

including drug delivery, water purification, detection 

and sensing, and enhanced oil recovery. For each of these 

applications, the size and shape of the polymeric nanoparticles 

in solution underlies its target functionality. For example, in 

the case of targeted drug delivery, both nanoparticle size and 

shape impact circulation times, cellular uptake, and potential 

toxicity. However, measuring the size and shape of polymeric 

nanoparticles in solution can be significantly more challenging 

than analyzing dry nanoparticles adsorbed to a surface, which 

may not reflect the true nanoparticle characteristics in solution. 

Here [1], we report small-angle neutron scattering (SANS) 

measurements to quantify the size, shape, and flexibility of 

bottlebrush polymers in solution. 

Bottlebrush polymers are nanoparticles with polymeric sidechains extending radially from a main-chain polymeric backbone 

and are promising for applications that rely on large, highly 

extended macromolecules and/or densely packed polymeric 

chains. These materials are of interest for drug delivery systems 

since the overall size and extension can in principle be controlled 

by the length and grafting density of the polymeric side-chains. 

However, a systematic study of bottlebrush polymer size and 

shape with varying molecular characteristics (backbone and sidechain length) has not been reported. 

Bottlebrush polymers have two main components; (1) a mainchain backbone polymer with M repeat units and (2) side-chain 

polymers of N repeat units that are chemically attached to the 

backbone (Fig. 1, top). Through optimized polymerization reactions [2] we can tailor both M and N independently. We utilized 

a “grafting-through” method in which the side-chains are first 

synthesized, followed by a polymerization reaction to generate 

the bottlebrush polymer. Side-chain polystyrene polymers were 

synthesized via reversible addition-fragmentation chain-transfer 

(RAFT) polymerization followed by ring opening metathesis 

polymerization (ROMP) to form the norbornene-functionalized backbone polymer. The PS bottlebrush polymers have 

side-chain molecular weights Mw from (3.1 to 6.9) kg mol-1, 

corresponding to side-chain degree of polymerization (DP) 

from N = 14 to N = 54, and overall molecular weights from

(36 to 3,140) kg mol-1, corresponding to backbone DP from 

M = 10 to M = 250. Bottlebrush polymer polydispersities (PDIs) 

range from 1.2 to 2.3. 

FIGURE 1: Schematic of a bottlebrush polymer (top) illustrating how the 

backbone length governs macromolecular length and side-chain polymers 

dictate radius or cross-sectional area. SANS data (bottom) and TEM micrograph 

(bottom, inset) for polystyrene bottlebrush polymers. Final PS bottlebrush 

polymers PNb(PSN)M have PS side chains with a degree of polymerization N

and a backbone with a degree of polymerization M.

SANS analysis was performed over a q-range of 0.008 Å-1

to 0.4 Å-1. This broad q-range provides information on the 

structure of bottlebrush polymers at multiple length scales. 

Roughly, the low-q region (0.008 < q (Å-1) < 0.02) gives 

information on the overall size of the bottlebrush polymer, 

the mid-q region (0.02 < q (Å-1) < 0.1) provides information 

about the cross sectional size and stiffness, and the high-q

region (q > 0.1 Å-1) is indicative of thermal fluctuations at the 

molecular level. SANS scattering curves are shown in Fig. 1. The 

plateau at low-q indicates fully dissolved bottlebrush polymers 

with little or no aggregates.

SANS data were analyzed using three different models. First, 

the Guinier-Porod model is a generic model that provides an 

estimate of overall size and shape for polymeric nanoparticles. 

Additionally, based on prior work with bottlebrush polymers 

[3,4], SANS data were analyzed using both rigid and semiflexible cylinder models, the latter of which can provide an 

estimate of backbone flexibility. All three models predict similar 

trends in the radius or cross-section of bottlebrush polymers. 

The bottlebrush polymer radius is found to depend on sidechain length, as expected based on the known structure. From 
2013 ACCOMPLISHMENTS AND OPPORTUNITIES 45SOFT MAT TER

the Guinier-Porod model, we observe a power-law dependence of the dimensions of the side-chains with side-chain DP, 

R ~ DP0.39. Using the radius R from the cylindrical form factor 

models provides a slightly larger exponent of 0.42 (Fig. 2a). 

These numbers suggest a 2-D or 3-D self-avoiding walk conformation of the polymeric side-chains. Side-chains show an average length per repeat unit greater than 1 nm in all cases, indicating they are strongly stretched. 

FIGURE 2: (a) Radius increase with side-chain length. (b) SANS data indicates 

that the backbone increases in length with increasing temperature. Error bars 

are one standard deviation.

Analysis of SANS data by both Guinier-Porod and cylindrical 

form factor models predict a sphere-to-cylinder transition with 

increasing backbone DP, shown schematically in Fig. 3. The 

results for PS bottlebrush polymers show a more elongated 

solution conformation for PS bottlebrush polymers with DPs 

greater than 120, while bottlebrush polymers with smaller 

backbone DPs are roughly spherical globules in solution. 

We can estimate the maximum dimension for bottlebrush 

polymers in solution using the Guinier-Porod model (diameter 

D= 2√2 Rg) for bottlebrush polymers with backbone DPs less 

than 120 and the length predictions for bottlebrush polymers 

with backbone DPs greater than 120. As shown in Fig. 3, this 

analysis predicts the maximum dimension is independent of 

backbone length below backbone DPs of 120, where side-chain 

stretching determines the size of the bottlebrush polymer. Above

a backbone DP of roughly 120, the maximum dimension increases 

with backbone DP. While we observe this conformational transition 

at a backbone DP of roughly 120, this transition will generally 

depend both on side-chain length, flexibility, and grafting density. 

FIGURE 3: Bottlebrush polymers undergo a conformational change from 

spherical to cylindrical after the backbone length extends beyond the 

diameter of the polymer. For polymers studied here, this transition occurs 

around backbone DP of 120. 

Our results from the flexible cylinder model further indicate that 

the backbone is not fully stretched, with lengths of backbone per 

monomer repeat unit, lb, roughly 0.18 nm ± 0.05 nm compared 

to the theoretical length for a fully extended backbone of roughly 

0.5 nm. For bottlebrush polymers with backbone DPs greater than 

120, temperature changes are found to only affect the backbone 

length and not bottlebrush polymer radius (Fig. 2b). This suggests 

that side-chains are highly stretched at all temperatures, while the 

backbone has more flexibility and reflects modest elongation with 

increasing temperature. 

Polymer nanoparticles have significant promise for a number of 

applications, but quantitative knowledge of their conformation 

and size in solution is needed. Here, we demonstrated that SANS 

analysis provides detailed information of the size and shape of 

bottlebrush polymers in solution. SANS measurement reveal a 

change in shape from spherical to cylindrical, for bottlebrush 

polymers with increasing backbone length. This has not been 

previously reported experimentally but is consistent with predictions 

of recent multi-scale molecular simulations of bottlebrush polymers. 

This finding has direct implications for the design and development 

of bottlebrush polymers for a wide variety of applications.

References

[1] S. L. Pesek, X. Li, B. Hammouda, R. Verduzco, 

Macromolecules 46 (17) 6998 (2013).

[2] Z. Li, J. Ma, N. S. Lee, K. L. Wooley, J. Am. Chem. Soc. 133

(5), 1228 (2011). 

[3] S. Rathgeber, T. Pakula, W. Agnieszka, K. Matyjaszewski, K. L. 

Beers, J. Chem. Phys. 122 (12), 124904 (2005). 

[4] B. Zhang, F. Grohn, J. S. Pederson, K. Fischer, M. Schmidt, 

Macromolecules 39 (24), 8440 (2006). 
46 NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY – NIST CENTER FOR NEUTRON RESEARCH ADVANCES IN MEASUREMENT

A shear cell designed to probe the velocity-velocity 

gradient (1-2) plane of shear in complex fluids

A. K. Gurnon1, P. D. Godfrin1, N. J. Wagner1, C. Lopez-Barron1, 2, A. P. R. Eberle1, 2, P. Butler2, C. Gagnon2,3, 

and L. Porcar1, 4

1

University of Delaware, Newark, DE 19716

2

NIST Center for Neutron Research, National Institute of Standards and 

Technology, Gaithersburg, MD 20899 3

University of Maryland, College Park, MD 20742

4

Institut Laue-Langevin, Grenoble Cedex 9, France

Anew shear cell sample geometry for complex fluids 

is optimized for SANS and USANS structure measurements at the NCNR that probes the most useful projection of the microstructure under flow; the 

velocity-velocity gradient (1-2) plane of shear (Fig. 1). The new 

NCNR sample environment is available for use on the three 

SANS (NG-3, NG-7, and 10m SANS) and USANS (BT-5) 

instruments at the NCNR and on D22 at the Institut LaueLangevin (ILL), as a collaborative development with the Center 

for Neutron Science at the University of Delaware and the ILL, 

Grenoble, France. Complex fluids encompass, but are not limited to, colloidal dispersions, surfactant solutions, emulsions, gels, 

glasses, proteins, biomaterials, foams, polymers and block copolymer solutions. Common to all is that oftentimes their processing and use involves flow. Hence, the study of soft matter forced 

out of equilibrium by shear flow is an important research area to 

improve formulation, processing, and manufacturing of complex 

fluids. The unique shear cell sample environment highlighted 

here represents a significant advance in our ability to understand 

the relationship between the microstructure of complex fluids 

and the macroscopic stress exhibited by these materials.

Recent manuscripts [1-3] discuss in varying detail the rheoand flow-SANS methods. The sealed Couette shear cell sample 

environment is designed to generate a laminar shear field while 

simultaneous microstructure measurements are made using 

SANS or USANS (Fig. 1) [3]. Investigating the evolution of 

velocity gradient dependent phenomenon, such as shear banding 

[7], is now possible by performing spatially-resolved experiments 

using a narrow slit aperture (Fig. 1) [4,5] during start-up flow 

[6] using time-resolution capabilities available at the NCNR. 

Example results of a time-resolved flow-SANS experiment 

(Fig. 2) are shown for a shear thickening colloidal suspension 

during large amplitude oscillatory shear (LAOS) using timeresolved SANS. The example 2D SANS patterns demonstrate 

the formation of hydroclusters corresponding to the highest 

shear rate and can be quantitatively used to determine the 

mechanism underlying the associated stress response [7,8]. This 

example illustrates just one of many uses for studying complex 

fluids under shear flow using the newly commissioned 1-2 

shear cell sample environment geometry in conjunction with 

spatial- and time-resolved neutron scattering methods at NIST. 

More information about this sample environment, including a 

video documenting its operation, is available from the Journal of 

Visual Experiments [3]. 

FIGURE 1: Left top: 1-2 shear cell geometry with velocity (1), velocity-gradient 

(2) and vorticity (3) shear directions indicated; bottom: counts as a function 

of position across the shear cell gap [3]. Right: Example of spatially resolved 

shear-banding.

FIGURE 2: Shear thickening fluid (SiO2 particles in d-ethylene glycol PEG-600 

(70/30), φeffective = 0.48) during LAOS (oscillation frequency ω = 10 rad/s and 

shear amplitude γ0 = 6278 %). The black line is the viscoelastic rheometry stress 

response reported as a Lissajous curve accompanied by 2D SANS results from 

experiments made in the 1-2 plane of shear.

References

[1] A. P. R. Eberle, L. Porcar, Curr. Opin. Colloid Interface Sci. 17, 

33 (2012).

[2] L. Porcar, et al., Rev. of Sci. Instrum. 82, 083902 (2011).

[3] A. K. Gurnon, et al., J. of Visual Exp. (In Press, 2013).

[4] M. W. Liberatore, et al., Phys. Rev. E 73, 020504 (2006). 

[5] M. E. Helgeson, et al., Phys. Rev. Lett. 105, 084501 (2010). 

[6] C. Lopez-Barron et al., Phys. Rev. Lett. (submitted 2013).

[7] N. J. Wagner, J. F. Brady, Phys. Today 62, 27 (2009).

[8] B. J. Maranzano, N. J. Wagner, J. Chem. Phys. 117, 

10291 (2002).
2013 ACCOMPLISHMENTS AND OPPORTUNITIES 47ADVANCES IN MEASUREMENT

Rapid and accurate calculation of small-angle 

scattering profiles using the golden ratio

M. C. Watson1 and J. E. Curtis1

1

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

S

mall-angle neutron and x-ray scattering have become 

invaluable tools for studying the nanoscale structure of 

biological molecules under near physiological conditions. 

While methods for measuring the overall size of 

molecules and the extent to which they are folded have long 

been established, determining three-dimensional molecular 

shape based on one dimensional small-angle scattering data 

remains one of the field’s greatest challenges. Achieving this ambitious goal has been made possible with the advent of modern 

computing, where the theoretical scattering profiles of millions 

of candidate structures are calculated until a configuration that 

agrees with the experimental data is found [1]. However, 

calculating the scattering intensity based on atomic positions 

is extremely time-consuming, and imposes a serious bottleneck 

on the interpretation of experimental measurements. Similar 

limitations are also encountered when calculating the average 

scattering profile in molecular simulations. 

We have devised a simple numerical method that significantly 

reduces this computational overhead [2]. While calculating the 

true scattering profile involves integrating over all scattering 

directions, we approximate it as a finite sum. The specific 

scattering directions used to evaluate the sum are chosen using 

the golden ratio, an irrational number known since the time of 

the ancient Greeks. Owing to a geometric property of the golden 

ratio, the scattering directions are uniformly distributed in all 

directions. This ‘golden vector’ approximation only consists of a 

few equations, allowing for easy customization [3].

The time required to calculate a scattering profile using the 

golden vector method scales as nN, where n is the number 

of scattering directions and N is the number of atoms in 

the molecule. The exact method scales as N2

. For biological 

molecules, N ranges from N = 103

 to N = 106. Taking four 

biomolecules as examples, we found that using n < 150 

orientations gives extremely accurate results (Fig. 1), offering 

tremendous time savings over the exact method. A previous 

approximation technique based on a multipole expansion [4] 

scales as NL2

 where L is the number of spherical harmonics. For 

a given level accuracy, we found that the golden vector method 

is much faster than the multipole technique for irregularly 

shaped molecules, while comparable in speed for quasi-spherical 

shapes (Fig. 2).

FIGURE 1: The calculated scattering profiles of lysozyme, MCM (mini 

chromosome maintenance complex), ferritin and a strand of DNA (images 

are not on the same scale). The red curves correspond to Debye’s exact, but 

computationally expensive formula [2]. The blue and green curves were 

obtained using the golden vector approximation for different numbers of 

scattering directions.

FIGURE 2: The speed improvement is shown as the calculation times required 

for the golden vector [3] and multipole expansion [4] techniques divided by 

the time needed to evaluate the exact formula. The timings shown correspond 

to 95 % agreement with the exact method.

Though we have examined cases involving a single type of 

biomolecule in a dilute solution, the golden vector method can 

be applied to a host of other systems. The scattering pattern of 

a flexible molecule can be obtained by calculating the scattering 

profile of each molecular conformation, and taking the ensemble 

average. Our method can be readily applied to simulations of 

interacting molecules by extending the sum to include all solute 

atoms. The analysis of x-ray and neutron powder diffraction data 

for many nanocrystalline materials relies on the same “candidate 

structure” approach as described above, and suffers from a 

similar computational bottleneck. The golden vector method 

may potentially expedite this analysis as well.

References

[1] P. Chacón et al., J. Mol. Biol. 299, 1289 (1998).

[2] B. Warren, X-ray Diffraction. (1990).

[3] M. C. Watson, J. E. Curtis, J. Appl. Cryst. 46, 1171 (2013).

[4] D. I. Svergun, C. Barberato, M. H. J. Koch. J. Appl. Cryst. 28, 

768 (1995).
48 NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY – NIST CENTER FOR NEUTRON RESEARCH ADVANCES IN MEASUREMENT

Advances in neutron flux measurement with the 

Alpha-Gamma device

A. T. Yue1,2,3, M. S. Dewey2, D. M. Gilliam2, G. L. Greene3,4, A. B. Laptev5,6, and J. S. Nico2

1

University of Maryland, College Park, MD 20742

2

Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899

3

University of Tennessee, Knoxville, TN 37996

4

Oak Ridge National Laboratory, Oak Ridge, TN 37831

5

Los Alamos National Laboratory, Los Alamos, NM 87545

6

Tulane University, New Orleans, LA 70118

Determining the flux (number of neutrons per second) 

of a neutron beam at the level of 0.1 % relative 

uncertainty has been an ongoing challenge for more 

than two decades, and it has applications in nuclear 

physics and neutron metrology. The ability to determine the 

flux at this precision is critical for beam-type neutron lifetime 

measurements [1], where the limiting systematic uncertainty has 

been the determination of the absolute neutron flux. A precise 

neutron flux technique will allow improved measurement of 

important neutron cross sections standards at near thermal 

energies, such as 6Li, 10B, and 235U, where there is little data [2]. 

It can also be used to calibrate the emission rate of NBS-1, the 

national standard Ra-Be photo-neutron source whose current 

emission rate uncertainty is 0.85 % [3]. We present the results 

from the Alpha-Gamma (AG) device, a totally absorbing 

neutron detector that was recently used to measure the neutron 

flux of beam line NG-6M to better than 0.1 % and to improve 

the uncertainty in the detection efficiency of an important 

neutron monitor by a factor of five.

The AG device determines the flux of neutrons impinging on a 

totally-absorbing 10B-enriched boron carbide target by counting 

the 478 keV 10B(n,γ)7Li reaction gamma rays with high-purity 

germanium (HPGe) detectors [4]. The flux is determined from 

the measured gamma rate and the absolute detection efficiency 

of the HPGe detectors for the capture gamma. The gamma 

detection efficiency is determined in a separate calibration procedure in which the precisely known activity of an alpha source 

is successively transferred through a series of intermediate steps.

The AG device and a thin 6LiF target-based neutron monitor 

were operated simultaneously on NG-6M, a monochromatic 

cold neutron beam (as shown in Fig. 1). A typical three-day 

measurement with the AG device determines the neutron 

flux to 0.07 % statistical uncertainty. The measured flux from 

the AG device and the measured rate of 6Li(n,t)4He reaction 

products in the neutron monitor are then used to determine the 

detection efficiency of the neutron monitor without reference to 

the 6Li(n,t)4He cross section or the target density. As shown in 

Fig. 2, data taken with three different beam collimations show 

good statistical consistency after correction for several systematic 

effects that may alter the efficiency. Including the uncertainties 

from systematic effects, the neutron monitor efficiency has been 

determined to 0.06 % with the AG device [5]. 

FIGURE 1: Schematic of the instrument setup on NG-6M.

FIGURE 2: Normalized flux monitor detection efficiency measurements with 

the AG device for three beam collimations. Corrections for systematic effects 

depending on beam collimation are included. The error bars (± σ) are statistical 

only. The dashed black line is a weighted fit to the data, and the grey bar 

represents the 1σ uncertainty on the fit.

The AG device has allowed us to perform high-precision neutron 

flux measurements on beam line NG-6M, directly measuring 

the detection efficiency of an important neutron monitor to 

levels of uncertainty previously unattainable. This reduced 

uncertainty provides improved calibration of neutron sources 

and has spurred a new effort to measure the neutron lifetime [6] 

with significantly reduced uncertainty. In addition, we are 

pursuing a program that for the first time would allow direct 

measurement of neutron capture cross sections.

References

[1] J. S. Nico, et al., Phys. Rev. C, 71, 055502 (2005).

[2] M. S. Dewey, et al., Proceedings of the 13th International 

Symposium on Reactor Dosimetry, 483 (2008).

[3] J. M. Adams, Nucl. Instrum. Methods B, 213, 218 (2004).

[4] D. M. Gilliam, et al., Nucl. Instrum. Methods A, 284, 220 (1989).

[5] A. T. Yue, Ph.D. Thesis, University of Tennessee (2011).

[6] M. S. Dewey, et al., Nucl. Instrum. Methods A, 611, 189 (2009).
2013 ACCOMPLISHMENTS AND OPPORTUNITIES 49

Neutron Source Operations

December 7, 2012 was the 45-year anniversary of the 

initial startup of the NBSR. Many things have changed 

at the facility since that afternoon in 1967 when the 

Reactor Operations staff posed for a group photo 

(Fig. 1) with their Chief of Reactor Operations, Tawfik Raby. To 

celebrate the years of continuous and successful reactor operation, 

Tawfik visited the NCNR control room at the exact moment 

(3:55 PM) that he supervised the first criticality of the NBSR.

NEUTRON SOURCE OPERATIONS

FIGURE 1: Tawfik Raby (front, center) and NBSR Reactor Operations and 

Engineering in 1967.

FIGURE 2: Tawfik Raby visiting the NBSR Control Room 45 years after initial 

reactor startup.

FIGURE 3: Number of NCNR Experimental Days per Fiscal Year 1999-2013.

FIGURE 4: Attila Halacsy and Greg Heller examine a new shim arm prior to 

installation.

This past fiscal year, the NBSR operated for 238 days with 98.5% 

reliability. Only four scheduled operational days were lost but two 

of these were made up by extending the impacted cycles. This year, 

lost days were due to the reactor and the NCNR being preemptively 

shutdown for over a day due to hurricane Sandy. Unplanned 

shutdowns in past years caused by equipment failures or power 

outages have been minimized. Even with unplanned shutdowns and 

an extended maintenance period in the summer, the NBSR provided 

slightly less than the average number of experimental days per year 

in FY13.

A major activity for ROE this year was the replacement of the four 

reactor control shim arms. These four, motor-driven and aluminumclad cadmium blades (arms) are used to control the NBSR power 

level and to shutdown the facility at the end of an experiment cycle. 

The arms must be replaced approximately every four years and this 

requires an extended shutdown (4 to 6 weeks). The longer shutdown 

and the removal of the shim arms this year provided an excellent 

opportunity to refurbish the four drive systems used by the reactor 

operators to remotely manipulate the arms and to upgrade a number 

of other reactor systems. All these activities were coordinated with 

Reactor Facility Operations (RFO) projects to minimize scheduling 

conflicts and the reactor restarted as scheduled at the end of the 

extended shutdown.

Progress towards the installation of a liquid deuterium source 

continued this year with the purchase of a new 7 kW helium 

refrigerator (expected delivery in early FY14) and the fabrication or 

ordering of several large components for the system. The operating 

large liquid hydrogen cold neutron source serving the guide hall 

has not been ignored and an upgraded control system for the 

source was purchased this year to assure that aging and obsolete 

components of the original system are replaced before failure. 

This instrumentation and control upgrade will not only provide 

enhanced reliability of the two operating liquid hydrogen cold 

sources but will be compatible with the new liquid deuterium cold 

source control system saving time and money when the new system 

is installed in a few years.

Reactor Operations and Engineering continues to work 

with the National Nuclear Security Agency (NNSA) and several 

national laboratories to develop a replacement reactor fuel that will 

allow the NCNR to use low enriched uranium (LEU) in the future. 

The fuel manufacturer and the NNSA must demonstrate the safety 

of the proposed fuel and its cost-effective manufacturability prior 

to the NBSR conversion to LEU. Safety analysis, fuel testing, and 

the development of a manufacturing process is on-going with an 

expected NBSR conversion sometime in the next decade prior to 

the NCNR receiving a planned additional 20-year operation license 

in 2029.
50 NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY – NIST CENTER FOR NEUTRON RESEARCH FACILIT Y DEVELOPMENT

Facility Development

F

acility support staff effort has focused on instrument 

installation and redeployment to capitalize on the 

new guide network and cold source infrastructure 

completed during the recent NCNR Expansion 

Initiative. 

Instrument Development

The Polarized Beam Reflectometer (PBR) and MAGIk, 

the new reflectometer dedicated to off-specular scattering, 

completed commissioning on guide NG-D and were the 

first instruments to enter the user program operating on 

the newly-installed supermirror guide network. Both 

instruments benefit from a larger beam area afforded by 

the new guide, with flux gains on PBR of nearly a factor ×3 

compared to the previous installation on NG-1. MAGIk 

is now operating routinely with the high-resolution 2-D 

Denex detector and will be the first instrument to migrate 

to the Facility’s new data acquisition and instrument control 

software – NICE (see below).

The NCNR’s small-angle neutron scattering capacity has also 

been enhanced following the installation and commissioning 

of a new 10 m SANS machine. The 10 m instrument 

is situated on NG-Blower, one of two low-divergence 

50 mm × 50 mm cross-section guides on the new network 

that will be dedicated to the SANS program. The 10 m 

SANS is the flagship instrument supporting the neutron 

scattering program of nSoft, the new NIST-led consortium 

of industrial, government, and academic members promoting 

research and development programs focused on high impact 

issues in soft materials manufacturing.

The final sections of the NG-A guide have now been installed 

ready to service the Neutron Spin Echo spectrometer, 

which is being relocated from its historical location on 

NG-5. The NG-A guide is strongly curved (on a radius of 

151 m) and direct line of sight is eliminated about 10 m 

from the cold source. The curvature has other operational 

advantages for the spectrometer, increasing its isolation from 

“contamination” from stray magnetic fields elsewhere in 

the Facility by gaining more distance from all neighboring 

beamlines. The final guide sections include a new polarizing 

cavity comprising supermirror coated “V”s of silicon wafers 

surrounded by 84 pieces of permanent magnet (NdFeB) 

to maintain a 500 G polarizing horizontal field for the 

supermirrors. The new polarizer promises improvements 

in beam polarization from the 80 % polarization at NG-5 

to ≈ 99 % at NG-A. The relocated instrument will also 

benefit from all new power supplies to replace the obsolete 

and increasingly unreliable units used at NG-5. The new 

units are now in place at NG-A and have been connected to 

a dedicated 480 V/600 A supply—this is at least an order of 

magnitude more power than required for typical instrument 

installations at the Facility. Commissioning activities for the 

Spin Echo instrument will start towards the end of the year.

FIGURE 1: Chuck Majkrzak aligns the new pyrolitic graphite monochromator 

for PBR inside the NG-D guide bunker.

In the confinement building, the cold-neutron Multi-Axis 

Crystal Spectrometer returned to user operations as MACS-II 

following its relocation from NG-0 to BT-9. The move 

was necessary in order to open up a viewport on the liquid 

hydrogen cold source for the new guide network, and a 

new dedicated cold source, “Peewee”, has been installed at 

BT-9 for MACS-II. The Peewee cold source has realized its 

design specification to provide a smaller (half the size) but 

brighter (factor ×2) source of cold neutrons optimized for 

the spectrometer and offering considerable gains in signal-tobackground for the typical sample sizes used in experiments 
2013 ACCOMPLISHMENTS AND OPPORTUNITIES 51FACILIT Y DEVELOPMENT

on the spectrometer. As part of the move, MACS was also 

upgraded to operate with a selection of cold filters on both 

the incident and scattered beams and, once again, these 

have already been shown to improve significantly signal-tobackground on the spectrometer. 

FIGURE 2: (left) Jim Moyer and Bill Clow install the monochromatic cold filter 

exchanger (MCFX) on the MACS analyzer system. (right) Danny Ogg and Eli 

Baltic lower into place the new incident beam cold filter exchanger (CFX) on 

MACS’ front end at BT-9.

Neutron Spin Filters

The NCNR promotes an active program, operated in 

collaboration with the Physical Measurement Laboratory at 

NIST, to provide and develop 3

He neutron spin filters (NSFs) 

to support high quality research using polarized neutrons. 

During the past year, the NCNR’s spin filter program 

serviced 15 user experiments, for a total of 58 days of beam 

time and 83 bar-liters of polarized 3

He gas.

Polarized beam experiments are routinely carried out on 

the thermal neutron triple-axis spectrometer BT-7 and on 

the small-angle neutron scattering instruments. 3

He gas 

is polarized by spin-exchange optical pumping (SEOP), in 

which alkali-metal atoms are polarized by optical pumping 

and the resulting electronic polarization is transferred to 

3

He nuclei in spin-exchange collisions. The goal is always 

to improve polarized neutronic performance and several 

large high-pressure cells have been successfully fabricated to 

meet demands of polarized inelastic experiments on BT-7. 

Improvements in polarization values have also been made, 

with a record value of 85 % in a large spin filter cell having 

now been achieved. The improvements were observed 

following conversion of the feedback element in the spectral 

narrowing scheme from a conventional diffraction grating 

to a chirped volume Bragg grating. The result, although 

welcome, was somewhat unexpected since prior studies had 

indicated that the alkali-metal polarization was unity and 

the 3

He polarization was limited to 80 % by the temperature 

dependence of 3

He relaxation under SEOP conditions. The 

origin of this gain is currently under investigation as the 

underlying physics likely has important implications for the 

limits of the SEOP technique.

Efforts continue to develop standard protocols for the routine 

use of NSFs in polarized neutron scattering measurements 

at the NCNR. These protocols include NMR and 3

He spin 

flipping devices and their associated software and an interface 

enabling communications between an instrument computer 

and IGOR-based 3

He NMR software. These user-friendly 

protocols have been implemented on dedicated spin filter 

apparatus for use on both BT-7 and the NG-3 and 

NG-7 SANS instruments. Similar systems are currently 

under development on the recently-commissioned MACS-II 

and MAGIk.

There have been a number of advances made on polarized 

neutron instrumentation for the individual instrument 

classes. For triple-axis experiments on BT-7 a polarized beam 

configuration has been implemented that capitalizes on earlier 

breakthroughs to reduce 3

He spin flip losses by two orders 

of magnitude and realize compact adiabatic spin rotation 

devices. Key features of the configuration include single or 

multiple adiabatic spin rotators, depending on whether the 

instrument is configured for polarization, P, perpendicular 

to Q, or P parallel to Q. The energy dependence and spatial 

uniformity of the spin transport has been characterized 

at better than 99 % for neutron energies up to 50 meV. 

Moreover, the spin transport efficiency is uniform over a wide 

range of scattering angles, a feature required in particular for 

the configuration of P parallel to Q. The nearly perfect spin 

transport is complemented by an observed flipping ratio of 

85 % with an intensity reduction factor of only 9.5 % as 

compared to an unpolarized beam configuration. This level 

of performance using a combination of a pyrolitic graphite 

monochromator and 3

He NSF is better than that achieved 

using Heusler crystal polarizers.

On the SANS instruments, polarization analysis development 

has focused on soft matter investigations. For a number of 

soft matter systems, extracting the weak coherent scattering 

from the sample at high Q is extremely challenging without 

accurate knowledge of the Q-independent nuclear spinincoherent background. Polarization analysis in combination 

with the time-of-flight (TOF) technique has been used to 

eliminate background from the inelastic scattering, and thus 

allow an accurate separation of coherent and spin-incoherent 

scattering. Refinement of the experimental procedures and 

data analysis methods for this technique is on-going and 

further tests of this challenging soft-matter application will be 

done in the future.

In addition, a compact in-situ SEOP system has been 

designed applicable for low-field SANS polarization 

analysis in both hard and soft matter research. The system 
52 NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY – NIST CENTER FOR NEUTRON RESEARCH FACILIT Y DEVELOPMENT

enables a constant 3He polarization to be maintained and 

decreases sensitivity to stray fields. The system incorporates 

a compact oven with silicon windows for neutron passage, 

a 

3

He flipping device, and a laser with associated optics and 

controllers. A dedicated system for NMR and 3

He spin 

flipping has been implemented and offline tests of the system 

are in progress.

Finally, following the commissioning of MACS-II, the 

development program for wide-angle neutron polarization 

analysis apparatus has restarted. The cells cover angles up to 

110° on either side of the neutron beam and the latest layout 

consists of a vertical, neutron-compatible, solenoid that 

contains a spin filter polarizer and analyzer cell situated close 

to the tail of a sample cryostat. The polarizer cell is contained 

in a shielded radio-frequency solenoid to permit inversion of 

the 3

He polarization via adiabatic fast passage NMR without 

loss of polarization in the analyzer cell. Free induction 

decay NMR is used to monitor the 3

He polarization in the 

spin filter cells. During preliminary testing a magnetic field 

gradient was discovered that led to reduced storage times for 

the polarized gas. A simple magnetic shield has since been 

used to block the stray fields originating from the MACS 

pre-sample optics without undue distortion of the highly 

homogeneous solenoid field. Further tests are required to 

validate this configuration but the research experiments using 

neutron polarization on MACS-II are expected to begin later 

his year.

Data Acquisition Software

Progress has continued in developing the New Instrument 

Control Environment software package (NICE) and the first 

deployment is now rolled out on MAGIk. The NICE project 

seeks ultimately to replace all the legacy software systems 

currently deployed at the NCNR with a modern and readilyextensible system common to all instrument classes. NICE 

is a Java-based package that incorporates a highly versatile 

scripting capability to enable end user adaptations to be 

coded under all the major scientific programing languages. 

Test releases of the new code are also available for the SANS 

instruments, the neutron spin echo spectrometer, and a basic 

triple-axis spectrometer.

Data Analysis Software

Development activity continues on the reflectometry analysis 

package, Refl1d, spawned from the DANSE (Distributed 

Data Analysis for Neutron Scattering Experiments) project. 

This package is used by many of our external users to fit 

their more complicated reflectometry models and a number 

of new features were added to make it easier to define and 

manipulate these models. 

Recently, bumps, the fitting engine at the core of Refl1d, has 

been separated from the fitting package and made available 

as a separate python application, which can be used to fit 

arbitrary models to data and report uncertainty in the fitting 

parameters. This program has been undergoing continual 

improvements to make it easier to construct models and share 

parameters between models for simultaneous fitting. Support 

for Message Passing Interface (MPI) parallelism has also been 

added to bumps, to facilitate runs on large computer clusters 

such as Kraken at Oak Ridge National Laboratory. 

The NCNR is also a contributor to the international SANS 

team working to develop the DANSE/SASview software 

package. The plug-in architecture has been redesigned to 

make it easier for developers and end users to add their own 

models in a compiled language and the first steps have been 

taken to incorporate the bumps fitting engine into SASView.

The Data Analysis and Visualization Environment (DAVE) 

project provides software solutions for a range of inelastic 

neutron scattering instruments at the NCNR and elsewhere. 

It is widely used by scientists to reduce, view and interpret 

their data and also for experiment planning. The software 

suite is fully supported on the three widely used computer 

platforms – Microsoft Windows, MacOS X and Linux and 

is freely available for download from the Internet. Currently, 

DAVE is a mature product with regards to its functionality, 

although it continues to evolve and expand to accommodate 

the needs of the Facility and its users. 

The data reduction module for the MACS instrument has 

been completely overhauled and is now fully supported 

through the Mslice reduction and analysis module. Thus 

visualizing and manipulating multiple datasets from MACS is 

more straightforward with the inclusion of slicing and cutting 

capabilities for volumetric data. In addition, experiment 

planning and scan setup tools are now available. For SPINS, 

a new reduction module is now in place for handling data 

from the position-sensitive detector. However, it is not 

yet feature complete as only data from powder samples is 

currently supported – support for a single crystal is planned. 

Numerous upgrades were applied to the BT-7 reduction 

software to support new features such as background 

subtraction, monitor correction and a raw view mode that 

adds to the existing powder and single crystal modes. 

A new genetic algorithm known as differential evolution 

(DE) is now an integral part of the peak analysis module 

(PAN) in DAVE. DE employs a population-based stochastic 

search approach to optimize the function parameters to 
2013 ACCOMPLISHMENTS AND OPPORTUNITIES 53FACILIT Y DEVELOPMENT

be fitted. In conventional DE, a mutation strategy and 

associated control parameters are selected to produce an 

evolution of the initial population of parameter vectors in 

future generations until a satisfactory solution is reached. 

Unfortunately, the performance of the algorithm is very 

sensitive to the choice of mutation strategy and the value of 

the control parameters. It is essentially problem-dependent. 

In our implementation we have employed a recent technique 

in which a pool of mutation strategies and control parameter 

values are used simultaneously and compete to produce a 

successful offspring generation. One significant advantage 

of this approach, which also happens to align perfectly with 

the goals of DAVE, is that the process is transparent to the 

end user since it is not necessary to make a choice about what 

mutation strategy to select. The end result is a DE algorithm 

that is as straightforward to use as the existing LevenbergMarquardt (LM) gradient search algorithm already in PAN. 

The LM algorithm remains the default but users can switch 

to and from the DE algorithm as required. However, for the 

DE, the user must specify the upper and lower bounds of the 

parameters to be fitted. In the figure, a fit of the “mean field 

order parameter” function to BT-7 data generally produces 

mixed results using the LM algorithm while switching to DE 

always produces an excellent fit as shown. 

FIGURE 3: Using the new Differential Evolution (DE) fitting algorithm in PAN to fit a mean field order parameter function to BT7 data. The user controls for the DE are 

shown in the bottom right section of the PAN interface. Using the Levenberg-Marquardt algorithm generally produces mixed results for this function. PAN uses the 

LM algorithm by default but switches to the DE algorithm if ‘Enable DE Algorithm’ is selected.
SERVING THE SCIENCE AND TECHNOLOGY COMMUNITY

54 NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY – NIST CENTER FOR NEUTRON RESEARCH

Serving the Science and Technology Community

The mission of the NIST Center for Neutron 

Research is to ensure the availability of neutron 

measurement capabilities to meet the needs of 

U.S. researchers from industry, academia and from 

other U.S. government agencies. To carry out this mission, 

the NCNR uses several different mechanisms to work with 

participants from outside NIST, including a competitive 

proposal process, instrument partnerships, and collaborative 

research with NIST.

Proposal System

Most of the time on NCNR instruments is made available 

through a competitive, peer-review proposal process. The 

NCNR issues calls for proposals approximately twice a 

year. Proposals are reviewed at several different levels. First, 

expert external referees evaluate each proposal on merit 

and provide us with written comments and ratings. This 

is a very thorough process where several different referees 

review each proposal. Second, the proposals are evaluated 

on technical feasibility and safety by NCNR staff. Third, we 

convene our Beam Time Allocation Committee (BTAC) to 

assess the reviews and to allocate the available instrument 

time. Using the results of the external peer review and their 

own judgment, the BTAC makes recommendations to the 

NCNR Director on the amount of beam time to allocate 

to each approved experiment. Approved experiments are 

scheduled by NCNR staff members in consultation with the 

experimenters.

The current BTAC members are:

n Andrew Allen (NIST Ceramics Division) 

n Jeffrey Allen (Michigan Technological University) 

n Collin Broholm (Johns Hopkins University) 

n Leslie Butler (Louisiana State University)

n Kushol Gupta (University of Pennsylvania) 

n Hye-Jung Kang (Clemson University)

n Ramanan Krishnamoorti (University of Houston)

n Valery Kiryukhin (Rutgers University) 

n Jennifer Lee (National Institutes of Health)

n Janna Maranas (The Pennsylvania State University) 

n Steven May (Drexel University)

n Alan Nakatani (Dow Chemical Company)

n Danilo Pozzo (University of Washington)

n Stephan Rosenkranz (Argonne National Laboratory)

n Gila Stein (University of Houston)

n Lynn Walker (Carnegie-Mellon University)

Partnerships

The NCNR may form partnerships with other institutions to 

fund the development and operation of selected instruments. 

These partnerships, or “Participating Research Teams”, may 

have access to as much as 75 % of the available beam time on 

the instrument depending on the share of total costs borne by 

the team. A minimum of 25 % of the available beam time is 

always made available through the NCNR proposal program 

to all users. Partnerships are negotiated for a fixed period 

(usually three years) and may be renewed if there is mutual 

interest and a continued need. These partnerships have 

proven to be an important and effective way to expand the 

research community’s access to NCNR capabilities and have 

been very successful in developing new instruments.

Collaboration With NIST

Some time on all instruments is available to NIST staff in 

support of our mission. This time is used to work on NIST 

research needs, instrument development, and promoting 

the widespread use of neutron measurements in important 

research areas, particularly by new users. As a result of these 

objectives, a significant fraction of the time available to NIST 

staff is used collaboratively by external users, who often take 

the lead in the research. Access through such collaborations 

is managed through written beam time requests. In contrast 

to proposals, beam time requests are reviewed and approved 

internally by NCNR staff. We encourage users interested in 

exploring collaborative research opportunities to contact an 

appropriate NCNR staff member.

Research Participation and 

Productivity

The NCNR continued its strong record of serving the U.S. 

research community this year. Over the 2013 reporting 

year, 2,148 research participants benefited from use of the 

NCNR. (Research participants comprise users who come to 

the NCNR to use the facility as well as active collaborators, 

including co-proposers of approved experiments, and coauthors of publications resulting from work performed at the 

NCNR.) As the number of participants has grown, the 

number of publications per year has increased proportionately. 

The quality of the publications has been maintained at a very 

high level. The trend of the past few years, however, suggests 

that the number of participants and publications is beginning 

to saturate, as one might expect as the capacity of the facility 

is reached. Completion of instruments associated with the 

Expansion Initiative that has taken place over the past few 

years promises increasing activity and productivity.
2013 ACCOMPLISHMENTS AND OPPORTUNITIES 55

FIGURE 1: Research participants at the NCNR 1986- 2013.

2013 NCNR Proposal Program

Two calls for proposals for instrument time were issued in 

the past year. We received 659 proposals, of which 393 were 

approved and received beam time. The oversubscription, i.e., 

the ratio of days requested on all proposals to the days 

available, was 2.1 on the average, but as high as 3.0 for 

specific instruments. Proposal demand has grown constantly 

since the NCNR first began accepting proposals in 1991, and 

has doubled in the past eight years. The following table shows 

the data for several instrument classes. 

SERVING THE SCIENCE AND TECHNOLOGY COMMUNITY

Instrument class Proposals Days 

requested

Days 

allocated

SANS and USANS 262 994 460

Reflectometers 113 728 348

Spectrometers 235 1581 714

Diffraction 21 65 46

Imaging 28 129 104

Total 659 3497 1672

Users Group Holds Election

The NCNR Users Group (NUG) provides an independent 

forum for all facility users to raise issues to NCNR 

management, working through its executive officers to carry 

out this function. The group held its fourth election in early 

2013, choosing four new members for the NUG Executive 

Committee. The newly elected members are Kate Gurnon 

(University of Delaware, student/postdoc member), (Alan 

Nakatani (Dow Chemical), Megan Robertson (University of 

Houston), and Michael Mackay (University of Delaware). 

Remaining on the committee are Despina Louca (University 

of Virginia, chair), John Katsaras (Oak Ridge National 

Laboratory), and Dale Schaefer (University of Cincinnati).

Panel Of Assessment

The major organizational components of NIST are evaluated 

annually for quality and effectiveness by the National 

Research Council (NRC), the principal operating agency of 

both the National Academy of Sciences and the National 

Academy of Engineering. A panel appointed by the NRC 

last reported on the NIST Center of Neutron Research in 

July 2013. The report from that meeting is not yet publicly 

available, but the findings of a prior meeting are summarized 

in a document that may be viewed online at http://www.nist.

gov/director/nrc/upload/nr-panel-2011-final-report.pdf. The 

panel members included Paul Fleury, Yale University, Laura 

Greene, University of Michigan, Andrew Harrison, Institut 

Laue-Langevin, Grenoble, Alan Hurd, Los Alamos National 

Laboratory, Dale Klein, University of Texas, Wade Konze, 

Dow Chemical, Roger Leach, DuPont Central Research and 

Development, Brian Maple, University of California, San 

Diego, and David Weitz, Harvard University. 

The Center For High Resolution 

Neutron Scattering (CHRNS)

CHRNS is a national user facility that is jointly funded 

by the National Science Foundation and the NCNR. Its 

primary goal is to maximize access to state-of-the-art neutron 

scattering instrumentation for the research community. It 

operates six neutron scattering instruments at the NCNR, 

enabling users from around the nation to observe dynamical 

phenomena involving energies from ≈ 30 neV to ≈ 100 meV, 

and to obtain structural information on length scales from 

≈ 1 nm to ≈ 10 μm. A more detailed account of CHRNS 

activities may be found on p. 57 of this report.

Partnerships For Specific Instruments

NG-7 SANS Consortium

A consortium that includes NIST, the ExxonMobil Research 

and Engineering Company, and the Industrial Partnership 

for Research in Interfacial and Materials Engineering 

(IPRIME) led by the University of Minnesota, operates, 

maintains, and conducts research at the NG-7 30 m SANS 

instrument. The consortium uses 57 % of the beam time on 

this instrument, with the remaining 43 % allocated to the 

general scientific community through the NCNR’s proposal 

system. Consortium members conduct independent research 

programs primarily in the area of large-scale structure in soft 

matter. For example, ExxonMobil has used this instrument 

to deepen their understanding of the underlying nature of 

ExxonMobil’s products and processes, especially in the fields 

of polymers, complex fluids, and petroleum mixtures. 
56 NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY – NIST CENTER FOR NEUTRON RESEARCH SERVING THE SCIENCE AND TECHNOLOGY COMMUNITY

The nSoft Consortium

Formed in August 2012, the nSoft Consortium allows 

member companies to participate with NIST in the 

development of advanced measurements of materials and 

manufacturing processes, and develop their own expertise 

in state-of-the-art measurement technologies to include 

in their analytical research programs. nSoft develops new 

neutron-based measurement science for manufacturers of soft 

materials including plastics, composites, protein solutions, 

surfactants, and colloidal fluids. Members receive access to 

leading expertise and training support in neutron technology 

and soft materials science at the NIST Center for Neutron 

Research, the NIST Materials Science and Engineering 

Division, and the University of Delaware. Contact: Ron 

Jones, nSoft Director, rljones@nist.gov, 301-975-4624.

NIST / General Motors – Neutron Imaging

An ongoing partnership and collaboration between General 

Motors and NIST continues to yield exciting results using 

neutron imaging. Neutron imaging has been employed to 

visualize the operation of fuel cells and lithium-ion batteries 

for automotive vehicle applications. Neutron imaging is 

an ideal method for visualizing hydrogen and lithium, the 

fuel of electric vehicle engines. These unique, fundamental 

measurements, provide valuable material characterizations 

that will help improve the performance, increase the 

reliability, and reduce the time to market introduction of 

the next generation electric car engines. 25 % of the time 

on the BT-2 Neutron Imaging Facility is made available to 

the general scientific community through peer-reviewed 

proposals.

Interagency Collaborations

The Smithsonian Institution’s Nuclear Laboratory for 

Archeological Research is part of the Anthropology 

Department at the National Museum of Natural History. It 

has had a productive 34 year partnership with the NCNR, 

during which time it has chemically analyzed over 43,100 

archaeological artifacts by Instrumental Neutron Activation 

Analysis (INAA), drawing extensively on the collections 

of the Smithsonian, as well as on those of many other 

institutions in this country and abroad. Such chemical 

analyses provide a means of linking these diverse collections 

together in order to study continuity and change involved in 

the production of ceramic and other artifacts.

The Center for Food Safety and Applied Nutrition, U.S. 

Food and Drug Administration (FDA), maintains laboratory 

facilities at the NCNR providing agency-wide analytical 

support for food safety and food defense programs. Neutron 

activation (instrumental, neutron-capture prompt-gamma, 

and radiochemical), x-ray fluorescence spectrometry, and 

low-level gamma-ray detection techniques yield multielement and radiological information about foods and 

related materials and provide a metrological foundation for 

FDA’s field investigations and for radiological emergency 

response planning. Current studies include development 

and validation of swordfish and cocoa powder in-house 

reference materials, measuring cesium levels in soil to study 

cesium uptake behavior into food products, rapid screening 

of food for dangerous levels of toxic elements, analysis of rice 

products for arsenic, and quantification of iodine in dietary 

supplements.
2013 ACCOMPLISHMENTS AND OPPORTUNITIES 57THE CENTER FOR HIGH RESOLUTION NEUTRON SCAT TERING (CHRNS)

The Center for High Resolution Neutron 

Scattering (CHRNS)

The Center for High Resolution Neutron Scattering 

is a national user facility that is jointly funded 

by the National Science Foundation through its 

Division of Materials Research (grant number 

DMR-0944772) and by the NCNR. The primary purpose 

of this partnership is to maximize access to state-of-theart neutron scattering instrumentation for the research 

community using the NCNR’s proposal system. Proposals 

to use the CHRNS instruments are critically reviewed on 

the basis of scientific merit and/or technological importance. 

The core mission of CHRNS is fourfold: (i) to develop and 

operate neutron scattering instrumentation, with broad 

application in materials research, for use by the general 

scientific community; (ii) to promote the effective use of the 

CHRNS instruments by having an identifiable staff whose 

primary function is to assist users; (iii) to conduct research 

that advances the capabilities and utilization of CHRNS 

facilities; and (iv) to contribute to the development of human 

resources through educational and outreach efforts.

FIGURE 1: Participants in the NCNR 2013 Summer School “Methods and Applications of Neutron Spectroscopy and SANS.”

Scattering Instruments and Research

During FY 2013, CHRNS supported operation of the 

following instruments: the NG-3 30 m Small Angle 

Neutron Scattering (SANS) instrument, the Ultra-Small 

Angle Neutron Scattering (USANS) instrument, the MultiAngle Crystal Spectrometer (MACS), the Disk Chopper 

Spectrometer (DCS), the High Flux Backscattering 

Spectrometer (HFBS), and the Neutron Spin-Echo (NSE) 

spectrometer. The small angle scattering instruments together 

provide structural information over length scales from 

≈ 1 nm to ≈ 10 μm. The spectrometers collectively yield 

dynamical information over time scales from ≈ 3 x 10-14 s to 

≈ 10-7 s (energy scales from ≈ 100 meV to ≈ 30 neV). These 

wide ranges of accessible distances and times support a very 

diverse scientific program, allowing researchers in materials 

science, chemistry, biology, and condensed matter physics 

to investigate materials such as polymers, metals, ceramics, 

magnetic materials, porous media, fluids and gels, and 

biological molecules.

In the most recent Call for Proposals (call 30), 236 proposals 

requested CHRNS instruments, and 124 of these proposals 

received beam time. Of the 1175 days requested for the 

CHRNS instruments, 497 were awarded. Corresponding 

numbers for all instruments were 340 proposals received, 

193 proposals approved, 1776 days requested, and 834 days 

awarded. Roughly half of the users of neutron scattering 

techniques at the NCNR use CHRNS-funded instruments, 

and more than one third of NCNR publications (see the 

“Publications” section on p. 62), over the current oneyear period, are based on research performed using these 

instruments. This reports contains several highlights of 

CHRNS publications. See the labeled highlights in the table 

of contents.

Scientific Support Services

CHRNS offers scientific support to our users in two critical 

areas: sample environment and chemical laboratories. The 

CHRNS Sample Environment team provides users with the 

equipment and training required to make measurements 

under special conditions of temperature, pressure, magnetic 

field, and fluid flow. This year the team commissioned a new 

3

He system that will be use with our 10 T magnet and our 

70 mm ILL cryostats, thus increasing our low temperature 
58 NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY – NIST CENTER FOR NEUTRON RESEARCH THE CENTER FOR HIGH RESOLUTION NEUTRON SCAT TERING (CHRNS)

capabilities. In order to improve our high temperature 

capabilities, the team commissioned two new high 

temperature CCR’s. In addition, other old and less reliable 

pieces of equipment have been replaced throughout the year. 

The laboratory staff continues work on developing training 

materials, helping users with their sample preparations, and 

keeping all our users laboratories in top shape. With nine 

laboratories dedicated to our users, the staff ensures that 

users have the tools and supplies they need for a successful 

experiment. 

Education and Outreach

This year the Center for High Resolution Neutron Scattering 

sponsored a variety of educational programs and activities 

tailored to specific age groups and professions. The annual 

summer school, held on June 17-20, 2013 was entitled 

“Methods and Applications of Neutron Spectroscopy and 

SANS”. Forty graduate and postdoctoral students from 23 

universities participated in the school. Lectures, research 

seminars and were highlighted for a wide variety of neutron 

measurement techniques. The guest lecturer was Prof. 

Stephen Wilson from Boston College. The evaluations were 

excellent and student feedback was very positive.

As part of its expanding education and outreach effort, 

CHRNS offers to university-based research groups with 

BTAC-approved experimental proposals the opportunity to 

request travel support for an additional graduate student to 

participate in the experiment. This support is intended to 

enable prospective thesis students, for example, to acquire 

first-hand experience with a technique that they may later 

use in their own research. Announcements of this program 

are sent to all of the university groups whose experimental 

proposals receive beam time from the BTAC. Recipients 

of the announcement are encouraged to consider graduate 

students from under-represented groups for this opportunity. 

The program is also advertised on the NCNR’s website at 

http://www.ncnr.nist.gov/outreach.html.

As in previous years, CHRNS participated in NIST’s Summer 

Undergraduate Research Fellowship (SURF) program. In 2013 

CHRNS hosted 13 SURF students. The students worked on a 

variety of projects including etch damage in magnetic thin-film 

sensors, dynamics of methanol/water mixtures, gas adsorption 

in metal-organic frameworks, pressure dependence of 

coordinated polymers, enhanced fitting engines for diffraction 

data refinement, and conceptual design of a new high-power 

research reactor. They presented their work at the NIST SURF 

colloquium in early August 2013.

The Summer High school Intern Program (SHIP) has been 

a very successful program with seven students participating 

this year. The students participated on research projects 

such as web-based data fitting, modeling off-specular 

x-ray scattering, minimizing roughness in permalloy thin 

films, and determining the glass transition temperature in 

confined polymer films. The results of the students’ summer 

investigations were highlighted in a NIST-wide poster 

session in early August, as well as in an oral symposium at 

the NCNR.

The NCNR initiated a Research Experiences for Teachers 

(RET) program in the summer of 2010. Wootton High 

School teacher Michael Thompson (Montgomery County, 

MD) was selected for the program for the summer of 

2012 and 2013. He collaborated with NCNR’s Joe Dura 

and SURF student Benjamin Jones from the University of 

Maryland on a project involving thin carbon films for battery 

and fuel cell applications.

FIGURE 2: The 2013 SURF students, NCNR director Rob Dimeo (left), CHRNS 

director Dan Neumann (second from left), and chief of reactor operations Sean 

O’Kelly (right).

FIGURE 3: Two of the NCNR’s SHIP students, Amy Lin and Mark Richardson 

from Winston Churchill High School (Potomac, MD) present their results at a 

NIST-wide symposium.
2013 ACCOMPLISHMENTS AND OPPORTUNITIES 59

The annual Summer Institute for Middle School Science 

Teachers brings middle school science teachers to NIST for 

two weeks in order to give them a better understanding of 

the scientific process. Each year, CHRNS hosts the teachers 

for a one-day introduction to neutron scattering with a 

presentation that describes how neutrons are produced and 

how they are used to improve our understanding of materials 

at the atomic scale. Having toured the neutron guide hall, 

and having seen several neutron instruments, the teachers 

learn about the types of experiments performed at the 

NCNR. To bring home projects suitable for middle school 

students, they then learn how to grow crystals of “alum” 

(hydrated aluminum potassium sulfate). Throughout the 

day and at lunchtime, the teachers have the opportunity to 

interact with staff members. 

Elementary, Middle, and High School 

Activities

As part of NIST’s activities for the annual “Take Your 

Daughters and Sons to Work Day”, CHRNS staff gave a 

presentation on what neutrons can do and offered a tour of 

the facility. The children, whose ages ranged from 12 years 

old to 15 years old, enjoyed watching the “Neutron Mouse 

Trap” (which demonstrates a “chain reaction” with mouse 

traps and ping pong balls).

22 tours for Middle School, High School, and University 

students were offered throughout the year.

“Adventures in Science” is a hands-on science program for 

middle school students with classes in physics, chemistry, 

computers, biology, astronomy, etc., taught by scientists, 

engineers, and technical professionals. Classes meet for about 

two hours on Saturday mornings from October through 

March. 

The NCNR and CHRNS staff developed a program to help 

Boy Scout troops from around the NIST area earn a Nuclear 

Science Merit Badge.

THE CENTER FOR HIGH RESOLUTION NEUTRON SCAT TERING (CHRNS)
60 NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY – NIST CENTER FOR NEUTRON RESEARCH 2013 AWARDS

2013 Awards

Shannon Watson and 

Wangchun Chen of the 

NCNR have been named the 

recipients of the 2013 Sigma 

Xi Award for Outstanding 

Scientific Support of NIST 

research scientists. This award recognizes their dedication in 

developing, producing, and delivering nuclear spin-polarized 

3

He gas cells used for neutron beam measurements. 

NCNR’s Kathryn Krycka was presented 

with the Young SANS Investigator Award

for her work on the magnetic morphology of 

nanoparticles during the 15th International 

Small-Angle Scattering Conference in 

Sydney, Australia.

David Mildner of the NCNR and an 

international group of co-workers received 

the Dal Swaine Award for the best paper 

in Coal and Hydrocarbon Source Rock 

Geochemistry, given by the Society for 

Organic Petrology. Their paper was titled 

“Pore size distribution and accessible pore size distribution in 

bituminous coals.”

Kim Tomasi has been selected to receive 

the NIST Colleague’s Choice Award. 

Kim is being recognized “For oversight in 

development, organization, and upkeep of 12 

laboratories and the design and maintenance 

of the laboratory safety program.” Kim 

Tomasi has also been selected to receive the organizational 

Safety Award as part of the NIST Biosafety Working Group. 

In particular they are being recognized “for their efforts in 

developing and promoting biosafety training and awareness 

for NIST staff.” The Safety Award is given to recognize NIST 

employees and organizations for substantial contributions to 

improving safety at NIST.

NCNR’s Yamali Hernandez,

Cindi Dennis (NIST MML), 

and NCNR's Julie Borchers 

received the NIST Equal 

Employment Opportunity/

Diversity Award “For 

extraordinary and voluntary effort into initiating and 

establishing the NIST Summer High School Internship 

Program (SHIP).”

NCNR’s Mike Dmitriou received first 

place at the Sigma Xi Post-doc Poster

Presentation for his poster entitled “The 

Effect of Tg Reduction on Chain Mobility in 

Confined Polystyrene Films.”

NCNR’s Brian Kirby received the NIST 

Bronze Medal. Brian is being recognized 

for “The elucidation of complex magnetic 

coupling in ferromagnetic, semiconducting 

multilayers using innovative polarized 

neutron reflectivity methods.”

NCNR’s William Ratcliff, Jr. received the 

NIST Bronze Medal for “His achievements 

in elucidating the magnetic and ferroelectric 

properties of BiFeO3, the leading contender 

for new spintronics technologies.”

NCNR’s Dan Dender, with Bruce Benner 

and Mike Kelley (NIST MML), and Adrian 

Mitchell and Carol Wood (NIST OFRM) 

were awarded the NIST Bronze Medal

“For improving the safety, efficiency, and 

effectiveness of the compressed gas program.”
2013 ACCOMPLISHMENTS AND OPPORTUNITIES 612013 AWARDS

Aaron Eberle from ExxonMobil was 

recognized for “Best Use of Small-Angle 

Neutron Scattering To an Industrial 

Application” presented at the 15th

International Small-Angle Scattering 

Conference in Sydney, Australia. Aaron was 

a post-doc at the NCNR and now leads the ExxonMobil 

program at the NCNR.

Norman Wagner, the Alvin B. and Julia O. 

Stiles Professor of Chemical Engineering at 

the University of Delaware, is the recipient 

of the 2013 Shell Global Solutions 

Thomas Baron Award. Prof. Wagner 

is being recognized for his excellence in 

colloidal suspension rheology fundamentals, developing new 

instrumentation, and translating these into breakthrough 

applications. This award recognizes an individual’s recent 

outstanding scientific/technical accomplishment that has 

made a significant impact in the field of fluid-particle systems 

or in a related field with potential for cross-fertilization. 

Norm is a frequent NCNR user.

Tyrel McQueen, assistant professor of 

chemistry at Johns Hopkins University 

received the 2013 ExxonMobil Solid-State 

Chemistry Faculty Fellowship. The award 

is administered by the ACS Division of 

Inorganic Chemistry, recognizing significant 

contributions to solid-state chemistry by an untenured faculty 

member at a U.S. institution. McQueen is a faculty member 

in Chemistry, as well as the Institute for Quantum Matter 

in Physics at Johns Hopkins University. His interdisciplinary 

research focuses on the discovery of new materials with 

unique physical properties, particularly those with strong 

electron correlation effects. Tyrel often uses the NCNR 

facilities for his work.

Kate Gurnon, a graduate student at the 

University of Delaware working with Prof. 

Norm Wagner won the Reg Davies Best 

Poster Award at the 2013 International 

Fine Particles Research Institute Annual 

Meeting held in Newark, DE. Her poster 

title was: “Microstructure-property Relationships for Novel 

Field-responsive Nanomaterials”. Kate also won 1st prize in 

the graduate student poster competition at the 85th Annual 

Meeting of the Society of Rheology, for her poster entitled 

“Spatiotemporal structure evolution and metastable states in 

shear banding wormlike micelles probed using LAOS and 

small angle neutron scattering.”

Simon Rogers, a post-doc working with 

Prof. Norm Wagner at the University of 

Delaware won 2nd prize in the post-doc 

poster competition at the 85th Annual 

Meeting of the Society of Rheology, for 

his poster on “The sequencing of dynamic 

rheological measurements.”
62 NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY – NIST CENTER FOR NEUTRON RESEARCH PUBLICATIONS

Publications: August 1, 2012 to July 31, 2013

Abriola, S.A., Bashir, J., Balagurov, A., Das, A., Edwards, 

L., Gnäupel-Herold, T., Goh, B., Ionita, I., Mikula, P., 

Ohms, C., Ridikas, D., Schneider, R.P., Sutiarso, S., 

Torok, G., Venter, A., Wimpory, R., “Development 

and Application of Residual Stress Measurement using 

Neutron Beams,” IAEA Tech. Rep. Series, edited by 

D.Ridikas, (International Atomic Energy Agency, 

Vienna, 2013), in press.

Abutaleb, M.O., Pushin, D.A., Huber, M.G., Majkrzak, 

C.F., Arif, M., Cory, D.G., “Design of Remnant 

Magnetization FeCoV Films as Compact, Heatless 

Neutron Spin Rotators,” Appl. Phys. Lett. 101(18), 

182404 (2012).

Anderson, D.L., Cunningham, W.C., “Analysis of 

FDA In-House Food Reference Materials with 

Anticoincidence INAA,” J. Radioanal. Nucl. Chem. 

296(1), 175 (2013).

Anderson, D.L., “Anticoincidence INAA Capabilities 

for Analysis of FDA Total Diet Study Seafoods,” J. 

Radioanal. Nucl. Chem. 296(1), 187 (2013).

Anderson, D.L., “INAA Study of Hg, Se, As, and Br 

Irradiation Losses from L-cysteine Treated and Untreated 

Reference Materials,” J. Radioanal. Nucl. Chem. 296(1), 

181 (2013).

Anderson, D.L., “Effect of L-cysteine on Drying and 

Neutron Irradiation Loss of Hg, Se, As, and Br from 

Fish Tissue,” J. Food Compos. Anal. 28(2), 88 (2012).

Anovitz, L.M., Cole, D.R., Rother, G., Allard, L.F., 

Jackson, A.J., Littrell, K.C., “Diagenetic Changes 

in Macro- to Nano-Scale Porosity in the St. Peter 

Sandstone: An (Ultra) Small Angle Neutron Scattering 

and Backscattered Electron Imaging Analysis,” 

Geochim. Cosmochim. Ac. 102, 280 (2013). 

[CHRNS]

Anovitz, L.M., Cole, D.R., Faulder, D.D., Sheets, J., Wang, 

H.-W., Rother, G., Wasbrough, M., Hjelm, R., Hartl, 

M., Pipich, V., Fu, Z., “Analysis of Multiscale Porosity 

at the Coso Geothermal Field,” in “Proceedings, 

Thirty-Eighth Workshop on Geothermal Reservoir 

Engineering,” (Stanford Geothermal Workshop, 

February 2013, Stanford, CA) SGP-TR-198 (2013). 

[CHRNS]

Arenas, D.J., Jegorel, T., Knab, C., Gasparov, L.V., Martin, 

C., Pajerowski, D.M., Kohno, H., Lufaso, M.W., 

“Raman Spectroscopy Evidence of Inhomogeneous 

Disorder in the Bismuth-Oxygen Framework of 

Bi25InO39 and Other Sillenites,” Phys. Rev. B 86(14), 

144116 (2012).

Armstrong, C.L., Toppozini, L., Dies, H., Faraone, A., 

Nagao, M., Rheinstädter, M.C., “Incoherent Neutron 

Spin-Echo Spectroscopy as an Option to Study LongRange Lipid Diffusion,” ISRN Biophys. 2013, 439758 

(2013). [CHRNS]

Arnold, D.E., Bohor, B.F., Neff, H., Feinman, G.M., 

Williams, P.R., Dussubieux, L., Bishop, R., “The 

First Direct Evidence of Pre-Columbian Sources of 

Palygorskite for Maya Blue,” J. Archaeol. Sci. 39(7), 

2252 (2012).

Azuah, R.T., Diallo, S.O., Adams, M.A., Kirichek, O., 

Glyde, H.R., “Phonon-Roton Modes of Liquid 4

He 

Beyond the Roton in the Porous Medium MCM-41,” 

Phys. Rev. B 88(2), 024510 (2013).

Bae, T.-H., Hudson, M.R., Mason, J.A., Queen, W.L., 

Dutton, J.J., Sumida, K., Micklash, K.J., Kaye, S.S., 

Brown, C.M., Long, J.R., “Evaluation of CationExchanged Zeolite Adsorbents for Post-Combustion 

Carbon Dioxide Capture,” Energ. Environ. Sci. 6(1), 

128 (2013).

Bao, W., Li, G.-N., Huang, Q.-Z., Chen, G.-F., He, J.-B., 

Wang, D.-M., Green, M.A., Qiu, Y.-M., Luo, J.-L., 

Wu, M.-M., “Superconductivity Tuned by the Iron 

Vacancy Order in KxFe2-ySe2,” Chinese Phys. Lett. 

30(2), 027402 (2013).

Bass, C.D., Beise, E.J., Breuer, H., Heimbach, C.R., 

Langford, T.J., Nico, J.S., “Characterization of a 6

LiLoaded Liquid Organic Scintillator for Fast Neutron 

Spectrometry and Thermal Neutron Detection,” Appl. 

Radiat. Isotopes 77, 130 (2013).

Bazilevskaya, E., Lebedeva, M., Pavich, M., Rother, G., 

Parkinson, D.Y., Cole, D., Brantley, S.L., “Where 

Fast Weathering Creates Thin Regolith and Slow 

Weathering Creates Thick Regolith,” Earth Surf. Proc. 

Land. 38(8), 847 (2013). [CHRNS]

Bentley, P.M., Kennedy, S.J., Andersen, K.H., Rodríguez, 

D.M., Mildner, D.F.R., “Correction of Optical 

Aberrations in Elliptic Neutron Guides,” Nucl. 

Instrum. Meth. A 693, 268 (2012).
2013 ACCOMPLISHMENTS AND OPPORTUNITIES 63PUBLICATIONS

Bertrand, C.E., Chiang, W.-S., Tyagi, M., Chen, S.-H., 

“Low-Temperature Water Dynamics in an Aqueous 

Methanol Solution,” J. Chem. Phys. 139(1), 014505 

(2013). [CHRNS]

Bertrand, C.E., Zhang, Y., Chen, S.-H., “Deeply-Cooled 

Water Under Strong Confinement: Neutron Scattering 

Investigations and the Liquid-Liquid Critical Point 

Hypothesis,” Phys. Chem. Chem. Phys. 15(3), 721 

(2013). [CHRNS]

Bingham, P., Polsky, Y., Anovitz, L., “Neutron Imaging 

for Geothermal Energy Systems,” in “Image 

Processing: Machine Vision Applications VI,” edited 

by Bingham, P.R., Lam, E.Y., (Proc. of SPIE-IS&T 

Electronic Imaging) 8661, 86610K (2013).

Bishop, R.L., Sears, E.L., Blackman, M.J., “Cerámicas 

en el borde occidental de las Tierras Baja Maya,” in 

“Arqueología de la costa de Campeche: La época 

prehispánica,” edited by Cobos, R., (Ediciones de la 

Universidad Autónoma de Yucatán, México) 187 (2012).

Blachowski, A., Ruebenbauer, K., Zajdel, P., Rodriguez, 

E.E., Green, M.A., “Mössbauer Study of the ‘11’ Ironbased Superconductors Parent Compound Fe1+xTe,” J. 

Phys.: Condens. Matter 24, 386006 (2012).

Blackburn, J.L., Engtrakul, C., Bult, J.B., Hurst, K., 

Zhao, Y., Xu, Q., Parilla, P.A., Simpson, L.J., Rocha, 

J.-D. R., Hudson, M.R., Brown, C.M., Gennett, T., 

“Spectroscopic Identification of Hydrogen Spillover 

Species in Ruthenium-modified High Surface Area 

Carbons by Diffuse Reflectance Infrared Fourier 

Transform Spectroscopy,” J. Phys. Chem. C 116(51), 

26744 (2012).

Boggara, M.B., Mihailescu, M., Krishnamoorti, R., 

“Structural Association of Nonsteroidal AntiInflammatory Drugs with Lipid Membranes,” J. Am. 

Chem. Soc. 134(48), 19669 (2012).

Budvytyte, R., Valincius, G., Niaura, G., Voiciuk, V., 

Mickevicius, M., Chapman, H., Goh, H.-Z., Shekhar, 

P., Heinrich, F., Shenoy, S., Lösche, M., Vanderah, D.J., 

“Structure and Properties of Tethered Bilayer Lipid 

Membranes with Unsaturated Anchor Molecules,” 

Langmuir 29(27), 8645 (2013).

Budvytyte, R., Mickevicius, M., Vanderah, D.J., Heinrich, 

F., Valincius, G., “Modification of Tethered Bilayers by 

Phospholipid Exchange with Vesicles,” Langmuir 29(13), 

4320 (2013).

Buss, H.L., Brantley, S.L., Scatena, F.N., Bazilievskaya, E.A., 

Blum, A., Schulz, M., Jiménez, R., White, A.F., Rother, 

G., Cole, D., “Probing the Deep Critical Zone Beneath 

the Luquillo Experimental Forest, Puerto Rico,” Earth 

Surf. Proc. Land., in press. [CHRNS]

Cappelletti, R.L., editor, “2012 NIST Center for Neutron 

Research Accomplishments and Opportunities,” NIST 

SP 1143 (2012).

Castañeda, C.A., Kashyap, T.R., Nakasone, M.A., Krueger, 

S., Fushman, D., “Unique Structural, Dynamical, and 

Functional Properties of K11-Linked Polyubiquitin 

Chains,” Structure 21(7), 1168 (2013). [CHRNS]

Chatterjee, T., Nakatani, A.I., Adden, R., Brackhagen, 

M., Redwine, D., Shen, H., Li, Y., Wilson, T., 

Sammler, R.L., “Structure and Properties of Aqueous 

Methylcellulose Gels by Small-Angle Neutron 

Scattering,” Biomacromolecules 13(10), 3355 (2012). 

[CHRNS]

Chen, S.-H., Wang, Z., Kolesnikov, A.I., Zhang, Y., Liu, 

K.-H., “Search for the First-Order Liquid-to-Liquid 

Phase Transition in Low-Temperature Confined 

Water by Neutron Scattering,” in “AIP Conference 

Proceedings,” edited by Takuyama, M., Oppenheim, I., 

(4th International Symposium on Slow Dynamics in 

Complex Systems, November 2012, Sendai) 1518, 77 

(2013). [CHRNS]

Chen, W. C., Erwin, R., Watson, S.M., “Neutron Path 

Length Correction of a 3

He Spin Filter,” in “Physics 

Procedia,” edited by Otto F., (Physics Procedia, June 

2012, Paris) 42, 163 (2013). [CHRNS]

Chen, X., Zhang, Y., Wang, Y., Zhou, W., Knight, D.A., 

Yisgedu, T.B., Huang, Z., Lingam, H.K., Billet, B., 

Udovic, T.J., Brown, G.M., Shore, S.G., Wolverton, 

C., Zhao, J.-C., “Structure Determination of an 

Amorphous Compound AlB4H11,” Chem. Sci. 3(11), 

3183 (2012).

Cheng, C.L., Kang, M., Perfect, E., Voisin, S., Horita, J., 

Bilheux, H.Z., Warren, J.M., Jacobson, D.L., Hussey, 

D.S., “Average Soil Water Retention Curves Measured 

by Neutron Radiography,” Soil Sci. Soc. Am. J. 76(4), 

1184 (2012).

Cho, K.T., Mench, M.M., “Investigation of the Role of 

the Micro-Porous Layer in Polymer Electrolyte Fuel 

Cells with Hydrogen Deuterium Contrast Neutron 

Radiography,” Phys. Chem. Chem. Phys. 14(12), 

4296 (2012).
64 NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY – NIST CENTER FOR NEUTRON RESEARCH PUBLICATIONS

Choi, D., Moon, J.H., Kim, H., Sung, B.J., Kim, 

M.W., Tae, G.Y., Satija, S.K., Akgun, B., Yu, C.-J., 

Lee, H.W., Lee, D.R., Henderson, J.M., Kwong, 

J.W., Lam, K.L., Lee, K.Y.C., Shin, K., “Insertion 

Mechanism of Cell-penetrating Peptides into 

Supported Phospholipid Membranes Revealed by 

X-ray and Neutron Reflection,” Soft Matter 8(32), 

8294 (2012).

Choi, J., Hore, M.J.A., Meth, J.S., Clarke, N., Winey, 

K.I., Composto, R.J., “Universal Scaling of Polymer 

Diffusion in Nanocomposites,” ACS Macro Letters 6, 

485 (2013). [CHRNS]

Choi, Y.J., Lee, N., Sharma, P.A., Kim, S.B., Vajk, 

O.P., Lynn, J.W., Oh, Y.S., Cheong, S.-W., “Giant 

Magnetic Fluctuations at the Critical Endpoint in 

Insulating HoMnO3,” Phys. Rev. Lett. 110(15), 

157202 (2013).

Chu, L., Wang, C., Bordet, P., Colin, C.V., Pairis, S., Na, 

Y., Yan, J., Huang, Q., “The Effect of Zn Vacancies on 

the Physical Properties of Antiperovskite Compounds 

Mn3ZnxN,” Scripta Mater. 68(12), 968 (2013).

Chung, J.-H., Lee, K.H., Song, Y.-S., Suzuki, T., Katsufuji, 

T., “Low Temperature Structural Instability of 

Tetragonal Spinel Mn3O4,” J. Phys. Soc. Jpn. 82, 

034707 (2013).

Chupp, T.E., Cooper, R. L., Coulter, K.P., Freedman, S.J., 

Fujikawa, B.K., García, A., Jones, G.L., Mumm, H.P., 

Nico, J.S., Thompson, A.K., Trull, C.A., Wietfeldt, 

F.E., Wilkerson, J.F., “Search for a T-odd, P-even 

Triple Correlation in Neutron Decay,” Phys. Rev. C 

86(3), 035505 (2012).

Chupp, T.E., Cooper, R.L., Coulter, K.P., Freedman, S.J., 

Fujikawa, B.K., Jones, G.L., García, A., Mumm, H.P., 

Nico, J.S., Thompson, A.K., Trull, C., Wietfeldt, 

F.E., Wilkerson, J.F., “Time Reversal and the Neutron 

Results of the emiT II Experiment,” Hyperfine Interact. 

214(1-3), 97 (2013).

Clapham, L., Babbar, V., Gnaüpel-Herold, T.H., Batisse, R., 

Zarea, M., “Neutron Diffraction Studies of Residual 

Stresses around Gouges and Gouged Dents,” in 

“Pipeline Integrity Management,” edited by American 

Society of Mechanical Engineers, (9th International 

Pipeline Conference, September 2012, Calgary, Alberta, 

Canada) 2, 747 (2012).

Clarkson, C.R., Solano, N., Bustin, R.M., Bustin, 

A.M.M., Chalmers, G.R.L., He, L., Melnichenko, 

Y.B., Radlińksi, A.P., Blach, T.P., “Pore Structure 

Characterization of North American Shale Gas 

Reservoirs using USANS/SANS, Gas Adsorption, and 

Mercury Intrusion,” Fuel 103, 606 (2013). [CHRNS]

Cockayne, E., Levin, I., Wu, H., Llobet, A., “Magnetic 

Structure of Bixbyite α-Mn2

O3: A combined DFT+U 

and Neutron Diffraction Study,” Phys. Rev. B 87(18), 

184413 (2013).

Colmenero, J. Arbe, A., “Recent Progress on Polymer 

Dynamics by Neutron Scattering: From Simple 

Polymers to Complex Materials”, J. Polymer Science B: 

Polymer Physics 51, 87 (2013).

Cooper, R.L., Alarcon, R., Bales, M.J., Bass, C.D., Beise, 

E.J., Breuer, H., Byrne, J., Chupp, T.E., Coakley, K.J., 

Dewey, M.S., Fu, C., Gentile, T.R., Mumm, H.P., 

Nico, J.S., O’Neill, B., Pulliam, K., Thompson, A.K., 

Wietfeldt, F.E., “A Gamma- and X-ray Detector for 

Cryogenic, High Magnetic Field Applications,” Nucl. 

Instrum. Meth. A 691, 64 (2012).

Crawford, M.K., Smalley, R.J., Cohen, G., Hogan, B., 

Wood, B., Kumar, S.K., Melnichenko, Y.B., He, L., 

Guise, W., Hammouda, B., “Chain Conformation in 

Polymer Nanocomposites with Uniformly Dispersed 

Nanoparticles,” Phys. Rev. Lett. 110(19), 196001 

(2013).

Cruz, J., Mihailescu, M., Wiedman, G., Herman, K., 

Searson, P.C., Wimley, W.C., Hristova, K., “A 

Membrane-Translocating Peptide Penetrates into 

Bilayers without Significant Bilayer Perturbations,” 

Biophys. J. 104(11), 2419 (2013).

Curtis, J.E., Nanda, H., Khodadadi, S., Cicerone, M., Lee, 

H.J., McAuley, A., Krueger, S., “Small-Angle Neutron 

Scattering Study of Protein Crowding in Liquid and 

Solid Phases: Lysozyme in Aqueous Solution, Frozen 

Solution, and Carbohydrate Powders,” J. Phys. Chem. B 

116, 9653 (2012). [CHRNS]

Curtis, J.E., McAuley, A., Nanda, H., Krueger, S., “Protein 

Structure and Interactions in the Solid State Studied by 

Small-Angle Neutron Scattering,” Faraday Discuss. 158, 

285 (2012). [CHRNS]

Das, P., Baumbach, R.E., Huang, K., Maple, M.B., Zhao, 

Y., Helton, J.S., Lynn, J.W., Bauer, E.D., Janoschek, 

M., “Absence of a Static In-plane Magnetic Moment in 

the ‘Hidden-Order’ Phase of URu2Si2,” New J. Phys. 

15, 053031 (2013).
2013 ACCOMPLISHMENTS AND OPPORTUNITIES 65PUBLICATIONS

Das, P., Densmore, J.M., Rastovski, C., Schlesinger, K.J., 

Laver, M., Dewhurst, C.D., Littrell, K., Bud’ko, S.L., 

Canfield, P.C., Eskildsen, M.R., “Field Dependence 

of the Superconducting Basal Plane Anisotropy of 

TmNi2Bi2C,”Phys. Rev. B 86(14), 144501 (2012).

Diamond, D.J., Hanson, A.L., Baek, J-S., Brown, N.R., 

Cuadra, A., Cheng, L.-Y., O’Kelly, D.S., Williams, R.E., 

Rowe, J.M., “Progress with the Conversion of the NIST 

Research Reactor,” in “Proceedings of RERTR 2012,” 

(RERTR 2012 - 34th International Meeting on Reduced 

Enrichment for Research and Test Reactors, September 

2012, Warsaw, Poland) (2012).

Dimeo, R., Ibberson, R., O’Kelly, S., Neumann, D., 

Cappelletti, R., Gehring, P., “The Expansion of the 

NIST Center for Neutron Research,” Neutron News 

24(1), 29 (2013).

Duan, X., Yu, J., Cai, J., He, Y., Wu, C., Zhou, W., Yildirim, 

T., Zhang, Z., Xiang, S., O’Keeffe, M., Chen, B., 

Qian, G., “A Microporous Metal-Organic Framework 

of a Rare Sty Topology for High CH4 Storage at Room 

Temperature,” Chem. Commun. 49(20), 2043 (2013).

Dumont, M.F., Risset, O.N., Knowles, E.S., Yamamoto, 

T., Pajerowski, D.M., Meisel, M.W., Talham, 

D.R., “Synthesis and Size Control of Iron(II) 

Hexacyanochromate(III) Nanoparticles and the Effect 

of Particle Size on Linkage Isomerism,” Inorg. Chem. 

52(8), 4494 (2013).

Dun, Z.L., Choi, E.S., Zhou, H.D., Hallas, A.M., 

Silverstein, H.J., Qiu, Y., Copley, J.R.D., Gardner, J.S., 

Wiebe, C.R., “Yb2Sn2O7: a Magnetic Coulomb Liquid 

at a Quantum Critical Point,” Phys. Rev. B 87(13), 

134408 (2013). [CHRNS]

Eastman, S.A., Kim, S., Page, K.A., Rowe, B.W., Kang, 

S., DeCaluwe, S.C., Dura, J.A., Soles, C.L., Yager, 

K.G., “Effect of Confinement on Structure, Water 

Solubility, and Water Transport in Nafion Thin 

Films,” Macromolecules 45(19), 7920 (2012).

Eberbeck, D., Dennis, C.L., Huls, N.F., Krycka, K.L., 

Grüttnerr, C., Westphal, F., “Multicore Magnetic 

Nanoparticles for Magnetic Particle Imaging,” IEEE 

T. Magn. 49(1), 269 (2013). [CHRNS]

Elliott, L.C.C., Jing, B., Akgun, B., Zhu, Y., Bohn, 

P.W., Fullerton-Shirey, S.K., “Loading and 

Distribution of a Model Small Molecule Drug in 

Poly(N- isopropylacrylamide) Brushes: a Neutron 

Reflectometry and AFM Study,” Langmuir 29(10), 

3259 (2013).

Enoki, M., Fujita, M., Nishizaki, T., Iikubo, S., Singh, 

D.K., Chang, S., Tranquada, J.M., Yamada, K., 

“Spin-Stripe Density Varies Linearly with the Hole 

Content in Single-Layer Bi2+xSr2-xCuO6+y Cuprate 

Superconductors,” Phys. Rev. Lett. 110(1), 017004 

(2013). [CHRNS]

Eriksson, S.M., Mackey, E.A., Lindstrom, R.M., Lamaze, 

G.P., Grogan, K.P., Brady, D.E., “Delayed-Neutron 

Activation Analysis at NIST,” J. Radioanal. Nucl. 

Chem., in press.

Fairweather, J.D., Spernjak, D., Weber, A.Z., Harvey, 

D., Wessel, S., Hussey, D.S., Jacobson, D.L., 

Artyushkova, K., Mukundan, R., Borup, R.L., 

“Effects of Cathode Corrosion on Through-Plane 

Water Transport in Proton Exchange Membrane Fuel 

Cells,” J. Electrochem. Soc. 160(9), F980 (2013).

Ferguson, P.P., Fleischauer, M.D., LaForge, J.M., Todd, 

A.D.W., Li, P., Dahn, J.R., “Studies of CoSn Grains 

in the Carbon Matrix Structure of Nanostructured 

Tin-Cobalt-Carbon,” J. Alloy Compd. 541, 168 

(2012). [CHRNS]

FitzGerald, P.A., McDonald, D.M., Warr, G.G., “The Effect 

of Degree of Polymerization on Intra- and Interchain 

Micellization of a Tail-Type Cationic Polysoap,” Soft 

Matter 9, 2711 (2013). [CHRNS]

FitzGerald, P.A., Warr, G.G., “Structure of Polymerizable 

Surfactant Micelles: Insights from Neutron 

Scattering,” Adv. Colloid. Interfac. Sci. 179-182, 14 

(2012). [CHRNS]

Foias, A.E., Bishop, R.L., “Ceramics, Production, and 

Exchange in the Petexbatun Region: The Economic 

Parameters of the Classic Maya Collapse,” in 

“Vanderbilt Institute of Mesoamerican Archaeology 

Series,” (Vanderbilt University Press) 7 (2013).

Fournier, P., Blackman, M.J., Bishop, R.L., “La 

arqueología histórica, etnoarqueología, y 

arqueometría aplicadas al estudio de las lozas 

vidriadas en Mexico: aproximaciones diacrónicas,” 

in “Haciendo Arqueología: Teoría, métodos y 

técnicas,” edited by Ladron, S. de Guevara, L. Budar, 

R. Lunagomez, (Universidad Veracruzana, Xalapa, 

Veracruz, Mexico) 131 (2012).

Fratini, E., Faraone, A., Ridi, F., Chen, S.-H., Baglioni, 

P., “Hydration Water Dynamics in Tricalcium Silicate 

Pastes by Time-Resolved Incoherent Elastic Neutron 

Scattering,” J. Phys. Chem. C 117(14), 7358 (2013).
66 NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY – NIST CENTER FOR NEUTRON RESEARCH PUBLICATIONS

Fritsch, K., Ross, K.A., Qiu, Y., Copley, J.R.D., Guidi, 

T., Bewley, R.I., Dabkowska, H.A., Gaulin, B.D., 

“Antiferromagnetic Spin Ice Correlations at (1⁄2,1⁄2,1⁄2) 

in the Ground State of the Pyrochlore Magnet 

Tb2Ti2O7,” Phys. Rev. B 87(9), 094410 (2013). 

[CHRNS]

Fritsch, K., Yamani, Z., Chang, S., Qiu, Y., Copley, 

J.R.D., Ramazanoglu, M., Dabkowska, H.A., 

Gaulin, B.D., “Magnetic Order and Fluctuations in 

the Presence of Quenched Disorder in the Kagome 

Staircase System (Co1-xMgx)3V2O8,” Phys. Rev. B 

86(17), 174421 (2012). [CHRNS]

Fu, R.S., Pasaogullari, U., Shiomi, T., Tabuchi, Y., Hussey, 

D.S., Jacobson, D.L., “High-Resolution Neutron 

Radiography of Through-Plane Liquid Water 

Distribution in Polymer Electrolyte Membrane and Gas 

Diffusion Layer,” J. Electrochem. Soc. 159(9), F545 

(2012).

Fujita, S., Kamazawa, K., Yamamoto, S., Tyagi, M., Araki, 

T., Sugiyama, J., Hasegawa, N., Kawasumi, M., “Proton 

Conductivity under Dry Conditions for Mesoporous 

Silica with Highly Dense Sulfonic Acid Groups,” J. Phys. 

Chem. C 117(17), 8727 (2013). [CHRNS]

García Sakai, V., Khodadadi, S., Cicerone, M.T., Curtis, J. 

E., Sokolov, A.P., Roh, J.H., “Solvent Effects on Protein 

Fast Dynamics: Implications for Biopreservation,” Soft 

Matter 9(22), 5336 (2013). [CHRNS]

García, A., Chupp, T.E., Cooper, R.L., Coulter, K.P., 

Freedman, S.J., Fujikawa, B.K., Jones, G.L., Mumm, 

H.P., Nico, J.S., Thompson, A.K., Trull, C.A., 

Wietfeldt, F.E., Wilkerson, J.F., “Search for T Violation 

in Neutron Decay: the emiT Experiment,” Lett. Nuovo 

Cimento 35C(4), 68 (2012).

Gaultois, M.W., Barton, P.T., Birkel, C.S., Misch, L.M., 

Rodriguez, E.E., Stucky, G.D., Seshadri, R., “Structural 

Disorder, Magnetism, and Electrical and Thermoelectric 

Properties of Pyrochlore Nd2Ru2O7,” J. Phys.: Condens. 

Matter 25(18), 186004 (2013).

Geier, S.J., Mason, J.A., Bloch, E.D., Queen, W.L., Hudson, 

M.R., Brown, C.M., Long, J.R., “Selective Adsorption 

of Ethylene over Ethane and Propylene over Propane in 

the Metal-Organic Frameworks M2 (dobdc) (M = Mg, 

Mn, Fe, Co, Ni, Zn),” Chem. Sci. 4(5), 2054 (2013).

Gentile, T.R., Hayden, M.E., Nacher, P.J., Petukhov, A.K., 

Saam, B., Walker, T.G., “Comment on ‘Enhanced 

Polarization and Mechanisms in Optically Pumped 

Hyperpolarized 3

He in the Presence of 4He,’” Phys. Rev. 

A 88(1), 017401 (2013).

Gericke, A., Leslie, N.R., Lösche, M., Ross, A.H., 

“PtdIns(4,5)P2-Mediated Cell Signaling: Emerging 

Principles and PTEN as a Paradigm for Regulatory 

Mechanism,” in “Advances in Experimental Medicine 

and Biology,” edited by Lambris, J.D., in press.

Gin, P., Jiang, N., Liang, C., Taniguchi, T., Akgun, B., Satija, 

S.K., Endoh, M.K., Koga, T., “Revealed Architectures 

of Adsorbed Polymer Chains at Solid-Polymer Melt 

Interfaces,” Phys. Rev. Lett. 109(26), 265501 (2012).

Glassman, M.J., Olsen, B.D., “Structure and 

Mechanical Response of Protein Hydrogels 

Reinforced by Block Copolymer Self-Assembly,” 

Soft Matter, in press.

Gnäupel-Herold, T.H., Iadicola, M.A., Creuziger, A.A., 

Foecke, T., Hu, L., “Interpretation of Diffraction 

Data from In-situ Stress Measurements during 

Biaxial Sheet Metal Forming,” Mater. Sci. Forum, in 

press.

Gnäupel-Herold, T.H., Green, D.E., Foecke, T.J., Iadicola, 

M.A., “Through-Thickness Stresses in Automotive 

Sheet Metal after Plane Strain Channel Draw,” Mater. 

Sci. Forum, in press.

Gorbachev, V.V., Cleveland, B.T., Gavrin, V.N., Ibragimova, 

T.V., Kalikhov, A.V., Nico, J.S., Veretenkin, E.P.V., “Ga 

Source Experiment for Detection of Short Baseline 

Neutrino Oscillations,” J. Phys.: Conf. Ser. 375(4), 

042068 (2012).

Granado, E., Lynn, J.W., Jardim, R.F., Torikachvili, M.S., 

“Two-Dimensional Magnetic Correlations and Partial 

Long-Range Order in Geometrically Frustrated 

Sr2YRuO6,” Phys. Rev. Lett. 110(1), 017202 (2013). 

Gupta, K., Curtis, J.E., Krueger, S., Hwang, Y., 

Cherepanov, P., Bushman, F.D., Van Duyne, G.D., 

“Solution Conformations of Prototype Foamy 

Virus Integrase and its Stable Synaptic Complex 

with U5 Viral DNA,” Structure 20(11), 1918 

(2012). [CHRNS]

Guralnick, B., Kirby, B.J., Majkrzak, C.F., Mackay, M.E., 

“Morphological Characterization of Plastic Solar Cells 

using Polarized Neutron Reflectivity,” Appl. Phys. 

Lett. 102(8), 083305 (2013).

Hallas, A.M., Paddison, J.A.M., Silverstein, H.J., Goodwin, 

A.L., Stewart, J.R., Wildes, A.R., Cheng, J.G., Zhou, 

J.S., Goodenough, J.B., Choi, E.S., Ehlers, G., Gardner, 

J.S., Wiebe, C.R., Zhou, H.D., “Statics and Dynamics 

of the Highly Correlated Spin Ice, Ho2Ge2O7,” Phys. 

Rev. B 86(13), 134431 (2012).
2013 ACCOMPLISHMENTS AND OPPORTUNITIES 67PUBLICATIONS

Hammouda, B., “Temperature Effect on the Nanostructure 

of SDS Micelles in Water,” J. Res. Natl. Inst. Stan. 

Tech. 118, 151 (2013). [CHRNS]

Hammouda, B., Mildner, D.F.R., Brûlet, A., Desert, 

S., “Insight into Neutron Focusing: the Outof-Focus Condition,” J. Appl. Crystallogr., in 

press. [CHRNS]

Han, T.-H., Helton, J.S., Chu, S., Nocera, D.G., 

Rodriguez-Rivera, J.A., Broholm, C., Lee, Y.S., 

“Fractionalized Excitations in the Spin-Liquid State of 

a Kagome-Lattice Antiferromagnet,” Nature 492, 406 

(2012). [CHRNS]

Hansen, F., Peters, G.H., Taub, H., Miskowiec, A., 

“Diffusion of Water and Selected Atoms in DMPC 

Lipid Bilayer Membranes,” J. Chem. Phys. 137(20), 

204910 (2012). [CHRNS]

Hardy, G.J., Nayak, R., Alam, S.M., Shapter, J.G., 

Heinrich, F., Zauscher, S., “Biomimetic Supported 

Lipid Bilayers with High Cholesterol Content 

Formed by α-helical Peptide-induced Vesicle Fusion,” 

J. Mater. Chem. 22, 19506 (2012).

Harriger, L.W., Liu, M., Luo, H., Ewings, R.A., Frost, C.D., 

Perring, T.G., Dai, P., “Temperature Dependence of the 

Paramagnetic Spin Excitations in BaFe2As2,” Phys. Rev. 

B 86(14), 140403 (2012).

Hayes, D.G., Alkhatib, M.H., Gomez del Rio, J., Urban, 

V.S., “Physicochemical Characterization of Water-in-oil 

Microemulsions formed by a Binary 1,3-dioxolane Alkyl 

Ethoxylate/Aerosol-OT Surfactant System,” Colloids 

Surf., A 417, 99 (2013). [CHRNS]

Hayre, N.R., Ross, K.A., Applegate, R., Lin, T., Singh, 

R.R.P., Gaulin, B.D., Gingras, M.J.P., “Thermodynamic 

Properties of Yb2Ti2O7 Pyrochlore as a Function of 

Temperature and Magnetic Field: Validation of a 

Quantum Spin Ice Exchange Hamiltonian,” Phys. Rev. B 

87(18), 184423 (2013).

He, C., Grutter, A.J., Gu, M., Browning, N.D., Takamura, 

Y., Kirby, B.J., Borchers, J.A., Kim, J.W., Fitzsimmons, 

M.R., Zhai, X., Mehta, V.V., Wong, F.J., Suzuki, Y., 

“Interfacial Ferromagnetism and Exchange Bias in 

CaRuO3/CamnO3 Superlattices,” Phys. Rev. Lett. 

109(19), 197202 (2012).

He, T., Wu, H., Chen, J., Zhou, W., Wu, G., Xiong, Z., 

Zhang, T., Chen, P., “Alkali and Alkaline-Earth Metal 

Borohydride Hydrazinates: Synthesis, Structures and 

Dehydrogenation,” Phys. Chem. Chem. Phys. 15(25), 

10487 (2013).

He, Y., Xiang, S., Zhang, Z., Xiong, S., Wu, C., Zhou, W., 

Yildirim, T., Krishna, R., Chen, B., “A Microporous 

Metal-Organic Framework Assembled from an Aromatic 

Tetracarboxylate for H2 Purification,” J. Mater. Chem. A 

1(7), 2543 (2013).

He, Y., Zhou, W., Krishna, R., Chen, B., “Microporous 

Metal-Organic Frameworks for Storage and Separation 

of Small Hydrocarbons,” Chem. Commun. 48(97), 

11813 (2012).

He, Y., Zhou, W., Yildirim, T., Chen, B., “A Series of MetalOrganic Frameworks with High Methane Uptake and 

an Empirical Equation for Predicting Methane Storage 

Capacity,” Energy Environ. Sci., in press.

Heeger, K.M., Tobin, M.N., Littlejohn, B.R., Mumm, H.P., 

“Experimental Parameters for a Reactor Antineutrino 

Experiment at Very Short Baselines,” Phys. Rev. D 

87(7), 073008 (2013).

Heinen, J.M., Blom, A.C.M., Hawkett, B.S., Warr, G.G., 

“Phase Behavior of Amphiphilic Diblock Co-oligomers 

with Nonionic and Ionic Hydrophilic Groups,” J. 

Phys. Chem. B 117(10), 3005 (2013).

Herm, Z.R., Wiers, B.M., Mason, J.A., van Baten, J.M., 

Hudson, M.R., Zajdel, P., Brown, C.M., Masciocchi, 

N., Krishna, R., Long, J.R., “Separation of Hexane 

Isomers in a Metal-Organic Framework with Triangular 

Channels,” Science 340, 960 (2013).

Herman, T.K., Parks, S.C., Scherschligt, J., “Thermal 

Equilibration of Samples for Neutron Scattering,” 

J. Appl. Crystallogr. 46, 279 (2013). [CHRNS]

Hirai, D., Bremholm, M., Allred, J.M., Krizan, J., Schoop, 

L.M., Huang, Q., Tao, J., Cava, R.J., “Spontaneous 

Formation of Zigzag Chains at the Metal-Insulator 

Transition in the β-Pyrochlore CsW2P6,” Phys. Rev.

Lett. 110(16), 166402 (2013).

Hong, L., Glass, D.C., Nickels, J.D., Perticaroli, S., Yi, 

Z., Tyagi, M., O’Neill, H., Zhang, Q., Sokolov, A.P., 

Smith, J.C., “Elastic and Conformational Softness of 

a Globular Protein,” Phys. Rev. Lett. 110(2), 028104 

(2013). [CHRNS]

Hong, T., Zhu, L.Y., Ke, X., Garlea, V.O., Qiu, Y., Nambu, 

Y., Yoshizawa, H., Zhu, M., Granroth, G.E., Savici, 

A.T., Gai, Z., Zhou, H.D., “Structural and Magnetic 

Properties in the Quantum S=1⁄2 Dimer System 

Ba3(Cr1-xVx)2O8 with Site Disorder,” Phys. Rev. B 

87(14), 144427 (2013). [CHRNS]
68 NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY – NIST CENTER FOR NEUTRON RESEARCH PUBLICATIONS

Hore, M.J.A., Composto, R.J., “Strategies for 

Dispersing, Assembling, and Orienting Nanorods 

in Polymers,” Curr. Opin. Chem. Eng. 2(1), 95 

(2013).

Horkay, F., Basser, P.J., Hecht, A.-M., Geissler, E., 

“Hierarchy and Organization of Hyaluronic Acid 

in Physiological Salt Solutions,” Polym. Mater. 

Sci. Eng. 107, 277 (2012). [CHRNS]

Horkay, F., “Interactions of Cartilage Extracellular Matrix 

Macromolecules,” J. Polym. Sci. B: Polym. Phys. 

50(24), 1699 (2012). [CHRNS]

Hou, H.-C., Kirby, B.J., Gao, K.Z., Lai, C.-H., 

“Characterizing Formation of Interfacial Domain 

Wall and Exchange Coupling Strength in Laminated 

Exchange Coupled Composites,” Appl. Phys. Lett. 

102(16), 162408 (2013).

Hould, N., Haouas, M., Nikolakis, V., Taulelle, F., 

Lobo, R.F., “Mechanisms of Quick Zeolite Beta 

Crystallization,” Chem. Mater. 24(18), 3621 (2012). 

[CHRNS]

Huang, B., Zhang, Y., Shu, X., Liu, Y., Penumadu, D., 

Ye, X. P., “Neutron Scattering for Moisture Detection 

in Foamed Asphalt,” J. Mater. Civil Eng. 25(7), 932 

(2013).

Hussey, D.S., Coakley, K.J., Baltic, E., Jacobson, D.L., 

“Improving Quantitative Neutron Radiography 

through Image Restoration,” Nucl. Instrum. Meth. A, 

in press.

Hussey, D.S., Spernjak, D., Weber, A.Z., Mukundan, R., 

Fairweather, J., Brosha, E.L., Davey, J., Spendelow, J.S., 

Jacobson, D.L., Borup, R.L., “Accurate Measurement 

of the Through-Plane Water Content of ProtonExchange Membranes using Neutron Radiography,” J. 

Appl. Phys. 112(10), 104906 (2012). 

Iida, K., Lee, S.-H., Onimaru, T., Matsubayashi, K., Sato, 

T.J., “Determination of Spin Hamiltonian in the Ni4

Magnetic Molecule,” Phys. Rev. B 86(6), 064422 

(2012). [CHRNS]

Inceoglu, S., Young, N.P., Jackson, A.J., Kline, S.R., 

Costeux, S., Balsara, N.P., “Effect of Supercritical 

Carbon Dioxide on the Thermodynamics of Model 

Blends of Styrene-Acrylonitrile Copolymer-Poly(methyl 

methacrylate) Studied by Small-Angle Neutron 

Scattering,” Macromolecules, in press. [CHRNS]

Jang, Y., Seo, J., Akgun, B., Satija, S., Char, K., “Molecular 

Weight Dependence on the Disintegration of SpinAssisted Weak Polyelectrolyte Multilayer Films,” 

Macromolecules 46(11), 4580 (2013).

Janson, O., Chen, S., Tsirlin, A.A., Hoffmann, S., 

Sichelschmidt, J., Huang, Q., Zhang, Z.-J., Tang, M.-

B., Zhao, J.-T., Kniep, R., Rosner, H., “Structure and 

Magnetism of Cr2[BP3O12]: Towards the QuantumClassical Crossover in a Spin-3/2 Alternating Chain,” 

Phys. Rev. B 87(6), 064417 (2013).

Jiang, P., Li, J., Ozarowski, A., Sleight, A.W., Subramanian, 

M.A., “Intense Turquoise and Green Colors in 

Brownmillerite-Type Oxides Based on Mn5+ in 

Ba2In2- xMnxO5+x,” Inorg. Chem. 52(3), 1349 (2013).

Kalinowski, A., Qin, Z., Coffey, K., Kodali, R., Buehler, 

M.J., Lösche, M., Dahl, K.N., “Calcium Causes a 

Conformational Change in Lamin A Tail Domain that 

Promotes Farnesyl-Mediated Membrane Association,” 

Biophys. J. 104(10), 2246 (2013).

Kihm, K., Kirchoff, E., Golden, M., Rosenfeld, J., Rawal, 

S., Pratt, D., Swanson, A., Bilheux, H., Walker, L., 

Voisin, S., Hussey, D.S., Jacobson, D.L., “Neutron 

Imaging of Alkali Metal Heat Pipes,” Physics Procedia 

43, 323 (2013).

Kilburn, D., Roh, J.H., Behrouzi, R., Briber, R.M., 

Woodson, S.A., “Crowders Perturb the Entropy of RNA 

Energy Landscapes to Favor Folding,” J. Am. Chem. 

Soc. 135(27), 10055 (2013).

Kim, J.M., Fang, J., Eberle, A.P.R., Castañeda-Priego, R., 

Wagner, N.J., “Gel Transition in Adhesive Hard-Sphere 

Colloidal Dispersions: The Role of Gravitational 

Effects,” Phys. Rev. Lett. 110(20), 208302 (2013). 

[CHRNS]

Kim, J., Gao, Y., Hebebrand, C., Peirtsegaele, E., Helgeson, 

M.E., “Polymer-Surfactant Complexation as a Generic 

Route to Responsive Viscoelastic Nanoemulsions,” Soft 

Matter, in press. [CHRNS]

Kim, S., Dura, J.A., Page, K.A., Rowe, B.W., Yager, K.G., 

Lee, H.-J., Soles, C.L., “Surface-Induced Nanostructure 

and Water Transport of Thin Proton-Conducting 

Polymer Films,” Macromolecules 46(14), 5630 (2013).

Kimura, K., Nakatsuji, S., Wen, J.-J., Broholm, C., Stone, 

M.B., Nishibori, E., Sawa, H., “Quantum Fluctuations 

in Spin-ice-like Pr2Zr2O7,” Nat. Commun. 4(1934), 1 

(2013). [CHRNS]
2013 ACCOMPLISHMENTS AND OPPORTUNITIES 69PUBLICATIONS

Kirby, B.J., Rahman, M.T., Dumas, R.K., Davies, J.E., Lai, 

C.-H., Liu, K., “Depth-resolved Magnetization Reversal 

in Nanoporous Perpendicular Anisotropy Multilayers,” J. 

Appl. Phys. 113(3), 033909 (2013).

Kirshenbaum, K., Butch, N.P., Saha, S.R., Zavalij, 

P.Y., Ueland, B.G., Lynn, J.W., Paglione, J., 

“Tuning Magnetism in FeAs-Based Materials via a 

Tetrahedral Structure,” Phys. Rev. B 86(6), 060504 

(2012).

Kitchen, B.B., Verdal, N., Udovic, T.J., Rush, J.J., Hartman, 

M.R., DeVries, D.J., “Investigation of an Unusual 

Low-Temperature Phase Transformation in RbBH4 by 

Neutron Diffraction,” J. Solid State Chem. 203, 51 

(2013).

Kizilay, E., Dinsmore, A.D., Hoagland, D.A., Sun, L., 

Dubin, P.L., “Evolution of Hierarchical Structures in 

Polyelectrolyte-Micelle Coacervates,” Soft Matter, in 

press. [CHRNS]

Kofu, M., Nagao, M., Ueki, T., Kitazawa, Y., Nakamura, 

Y., Sawamura, S., Watanabe, M., Yamamuro, O., 

“Heterogeneous Slow Dynamics of ImidazoliumBased Ionic Liquids Studied by Neutron Spin Echo,” 

J. Phys. Chem. B 117(9), 2773 (2013). [CHRNS]

Krycka, K.L., Borchers, J.A., Laver, M., Salazar-Alvarez, 

G., López-Ortega, A., Estrader, M., Suriñach, 

S., Baró, M.D., Sort, J., Nogués, J., “Correlating 

Material-Specific Layers and Magnetic Distributions 

within Onion-Like Fe3O4|MnO|γ-Mn2O3 Core/Shell 

Nanoparticles,”J. Appl. Phys. 113(17), 17B531-1 

(2013). [CHRNS]

Krycka, K.L., Borchers, J.A., Salazar-Alvarez, G., LópezOrtega, A., Estrader, M., Estradé, S., Winkler, E., 

Zysler, R.D., Sort, J., Peiró, F., Baró, M.D., Kao, C.-

C., Nogués, J., “Resolving Material-Specific Structures 

within Fe3O4|γ-Mn2O3 Core|Shell Nanoparticles Using 

Anomalous Small-Angle X-ray Scattering,” ACS Nano 

7(2), 921 (2013). [CHRNS]

Kumari, H., Kline, S.R., Dennis, C.L., Mossine, A.V., Paul, 

R.L., Deakyne, C.A., Atwood, J.L., “Solution-Phase 

and Magnetic Approach Towards Understanding Iron 

Gall Ink-like Nanoassemblies,” Angew. Chem. Int. Ed. 

37, 9263 (2012). 

Kumari, H., Kline, S.R., Wycoff, W.G., Atwood, J.L., 

“Investigating Structural Alterations in Pyrogallol[4] 

Arene-Pyrene Nanotubular Frameworks,” Small 

8(21), 3321 (2012).

Kumi, B.C., Greer, S.C., “Micelles of Polybutadiene-bpoly(ethylene oxide) in Deuterated Methanol and 

Deuterated Cyclohexane,” J. Colloid Interf. Sci. 

386(1), 212 (2012). [CHRNS]

Langford, T.J., Bass, C.D., Beise, E.J., Breuer, H., 

Erwin, D.K., Heimbach, C.R., Nico, J.S., “Event 

Identification 3

He Proportional Counters using 

Risetime Discrimination,” Nucl. Instrum. Meth. A 

717, 51 (2013).

Lee, H.B., Chun, S.H., Shin, K.W., Jeon, B.-G., Chai, Y.S., 

Kim, K.H., Schefer, J., Chang, H., Yun, S.-N., Joung, 

T.-Y., Chung, J.-H., “Heliconical Magnetic Order 

and Field-Induced Multiferroicity of the Co2Y-type 

Hexaferrite Ba0.3Sr1.7Co2Fe12O22,” Phys. Rev. B 86(9), 

094435 (2012).

Lee, H.-Y., Hashizaki, K., Diehn, K., Raghavan, S.R., 

“Reverse Self-Assembly of Lipid Onions Induced by 

Gadolinium and Calcium Ions,” Soft Matter 9(1), 

200 (2013). [CHRNS]

Lee, J., Stone, M.B., Huq, A., Yildirim, T., Ehlers, G., 

Mizuguchi, Y., Miura, O., Takano, Y., Deguchi, K., 

Demura, S., Lee, S.-H., “Crystal Structure, Lattice 

Vibrations, and Superconductivity of LaO1-xFxBiS2,” 

Phys. Rev. B 87(20), 205134 (2013).

Li, G., Rao, G., Huang, Q., Gao, Q., Luo, J., Liu, 

G., Li, J., Liang, J., “Phase Precipitation in the 

Bi1-xCaxMnO3 Compounds (x=0.4-0.6),” Europhys. 

Lett. 101, 67004 (2013).

Li, X., Malardier-Jugroot, C., “Confinement Effect in the 

Synthesis of Polypyrrole within Polymeric Templates in 

Aqueous Environments,” Macromolecules 46(6), 2258 

(2013). [CHRNS]

Lin, K.-J., Maranas, J.K., “Cation Coordination and Motion 

in a Poly(ethylene oxide)-Based Single Ion Conductor,” 

Macromolecules 45, 6230 (2012). [CHRNS]

Liu, D., Hussey, D., Gubarev, M.V., Ramsey, B.D., 

Jacobson, D., Arif, M., Moncton, D.E., Khaykovich, 

B., “Demonstration of Achromatic Cold-Neutron 

Microscope Utilizing Axisymmetric Focusing Mirrors,” 

Appl. Phys. Lett. 102(18), 183508 (2013).

Liu, X., Majzoub, E.H., Stavila, V., Bhakta, R.K., Allendorf, 

M.D., Shane, D.T., Conradi, M.S., Verdal, N., 

Udovic, T.J., Hwang, S.-J., “Probing the Unusual 

Anion Mobility of LiBH4 Confined in Highly Ordered 

Nanoporous Carbon Frameworks via Solid State NMR 

and Quasielastic Neutron Scattering,” J. Phys. Chem. A, 

in press. [CHRNS]
70 NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY – NIST CENTER FOR NEUTRON RESEARCH PUBLICATIONS

Liu, Y., Brown, C.M., Neumann, D.A., Geohegan, D.B., 

Puretzky, A.A., Rouleau, C.M., Hu, H., StyersBarnett, D., Krasnov, P.O., Yakobson, B.I., “MetalAssisted Hydrogen Storage on Pt-Decorated SingleWalled Carbon Nanohorns,” Carbon 50(13), 4953 

(2012).

Livingston, R., Nemes, N., Neumann, D., “QuasiElastic Neutron Scattering Investigation of the 

Effect of Water/Cement Ratio on Tricalcium Silicate 

Hydration,” in “13th International Conference on the 

Chemistry of Cement,” edited by Palomo, A., Zaragoze 

A., Agui, J., (ICCC, 2011, Madrid, Conf. Proc.) 

(2011).

Long, G.G., Chapman, K.W., Chupas, P.J., Bendersky, 

L.A., Levine, L.E., Mompiou, F., Stalick, J.K., Cahn, 

J.W., “Highly Ordered Noncrystalline Metallic Phase,” 

Phys. Rev. Lett. 111(1), 015502 (2013). 

López-Barrón, C.R., Wagner, N.J., “Structural Transitions 

of CTAB Micelles in a Protic Ionic Liquid,” Langmuir 

28(35), 12722 (2012).

López-Barrón, C.R., Li, D., DeRita, L., Basavaraj, M.G., 

Wagner, N.J., “Spontaneous Thermoreversible 

Formation of Cationic Vesicles in a Protic Ionic 

Liquid,” J. Am. Chem. Soc. 134(51), 20728 (2012). 

[CHRNS]

Lott, J.R., McAllister, J.W., Arvidson, S.A., Bates, 

F.S., Lodge, T.P., “Fibrillar Structure of 

Methylcellulose Hydrogels,” Biomacromolecules, 

in press.

Luo, J., Wu, H., Zhou, W., Kang, X., Wang, P., 

“Li2(NH2BH3)(BH4)/LiNH2BH3: the First 

Metal Amidoborane Borohydride Complex with 

Inseparable Amidoborane Precursor for Hydrogen 

Storage,” Int. J. Hydrogen Energ. 38(1), 197 

(2013).

Luzin, V., Prask, H. J., Gnäupel-Herold, T., Gordon, 

J., Wexler, D., Rathod, C.H., Pal, S., Daniel, W., 

Atrens, A., “Neutron Residual Stress Measurements 

in Rails,” Neutron News 24(3), 9 (2013).

Lynn, J.W., “Magnetic Neutron Scattering,” in 

“Characterization of Materials, 1st ed.,” edited by 

Kaufmann, E.N. (Wiley & Sons, Inc., Hoboken, 

NJ), 1328 (2012).

Magiera, J., “Validation of an Experimental Technique 

with the Physically Based Global Method,” CAMES 

19(4), 369 (2012).

Majkrzak, C., Borchers, J., “2012 American Conference 

on Neutron Scattering (ACNS 2012),” Neutron 

News 23(4), 7 (2012).

Manahan, M.P., Mench, M.M., “Laser Perforated 

Fuel Cell Diffusion Media: Engineered Interfaces 

for Improved Ionic and Oxygen Transport,” J. 

Electrochem. Soc. 159(7), F322 (2012).

Mang, J.T., Hjelm, R.P., “Fractal Networks of InterGranular Voids in Pressed TATB,” Propell. Explos. 

Pyrot., in press.

Manson, J.L., Brown, C.M., Huang, Q., Schlueter, 

J.A., Lancaster, T., Blundell, S.J., Singleton, J., 

Lynn, J.W., Pratt, F.L., “Mn(dca)2(o-phen){dca = 

dicyanamide; o- phen =1,10-Phenanthroline}: LongRange Magnetic Order in a Low-Dimensional Mndca Polymer,” Polyhedron 52, 679 (2013).

Marquardt, D., Williams, J.A., Kučerka, N., Atkinson, J., 

Wassall, S.R., Katsaras, J., Harroun, T.A., “Tocopherol 

Activity Correlates with Its Location in a Membrane: 

A New Perspective on the Antioxidant Vitamin E,” J. 

Am. Chem. Soc. 135(20), 7523 (2013).

Mastalerz, M., He, L., Melnichenko, Y.B., Rupp, J.A., 

“Porosity of Coal and Shale: Insights from Gas 

Adsorption and SANS/USANS Techniques,” Energ. 

Fuel. 26(8), 5109 (2012). [CHRNS]

Miao, Y., Yi, Z., Cantrell, C., Glass, D.C., Baudry, J., 

Jain, N., Smith, J.C., “Coupled Flexibility Change in 

Cytochrome P450cam Substrate Binding Determined 

by Neutron Scattering, NMR, and Molecular 

Dynamics Simulation,” Biophys. J. 103(10), 2167 

(2012). [CHRNS]

Miao, Y., Yi, Z., Glass, D.C., Hong, L., Tyagi, M., Baudry, 

J., Jain, N., Smith, J.C., “Temperature-Dependent 

Dynamical Transitions of Different Classes of Amino 

Acid Residue in a Globular Protein,” J. Am. Chem. Soc. 

134(48), 19576 (2012). [CHRNS]

Mossine, A.V., Kumari, H., Fowler, D.A., Shih, A., Kline, 

S.R., Barnes, C.L., Atwood, J.L., “Ferrocene Species 

Included within a Pyrogallo[4]arene Tube,” Chem.-Eur. 

J. 18(33), 10258 (2012).

Mulligan, P.L., Cao, L.R., Turkoglu, D., “A Multi-detector, 

Digitizer Based Neutron Depth Profiling Device for 

Characterizing Thin Film Materials,” Rev. Sci. Instrum. 

83(7), 073303 (2012).
2013 ACCOMPLISHMENTS AND OPPORTUNITIES 71PUBLICATIONS

Murnen, H.K., Rosales, A.M., Dobrynin, A.V., 

Zuckermann, R.N., Segalman, R.A., “Persistence 

Length of Polyelectrolytes with Precisely Located 

Charges,” Soft Matter 9(1), 90 (2013). [CHRNS]

Nagpure, S.C., Downing, R.G., Bhushan, B., Babu, S.S., 

“Discovery of Lithium in Copper Current Collectors 

used in Batteries,” Scripta Mater. 67(7-8), 669 (2012).

Nakano, K., Yajima, T., Takeiri, F., Green, M.A., Hester, 

J., Kobayashi, Y., Kageyama, H., “Tc Enhancement by 

Aliovalent Anionic Substitution in Superconducting 

BaTi2(Sb1-xSnx)2O,” J. Phys. Soc. Jpn. 82(7), 074707 

(2013).

Natali Sora, I., Caronna, T., Fontana, F., de Julián 

Fernández, C., Caneschi, A., Green, M.A., Bonville, 

P., “Charge Compensation and Magnetic Properties 

in Sr and Cu Doped La-Fe Perovskites,” EPJ Web of 

Conferences 40, 15005 (2013).

Navarre-Sitchler, A.K., Cole, D.R., Rother, G., Jin, L., 

Buss, H.L., Brantley, S.L., “Porosity and Surface Area 

Evolution during Weathering of Two Igneous Rocks,” 

Geochim. Cosmochim. Acta. 109, 400 (2013). 

[CHRNS]

Newbloom, G.M., Weigandt, K.M., Pozzo, D.C., “Structure 

and Property Development of Poly(3-hexylthiophene) 

Organogels Probed with Combined Rheology, 

Conductivity and Small Angle Neutron Scattering,” Soft 

Matter 8(34), 8854 (2012).

Nickels, J.D., O’Neill, H., Hong, L., Tyagi, M., Ehlers, 

G., Weiss, K.L., Zhang, Q., Yi, Z., Mamontov, E., 

Smith, J.C., Sokolov, A.P., “Dynamics of Protein and 

its Hydration Water: Neutron Scattering Studies on 

Fully Deuterated GFP,” Biophys. J. 103(7), 1566 

(2012). [CHRNS]

Njauw, C.-W., Cheng, C.-Y., Ivanov, V.A., Khokhlov, A.R., 

Tung, S.-H., “Molecular Interactions between Lecithin 

and Bile Salts/Acids in Oils and Their Effects on Reverse 

Micellization,” Langmuir 29(12), 3879 (2013).

Ogunsola, O.A., Kraeling, M.E., Zhong, S., Pochan, D.J., 

Bronaugh, R.L., Raghavan, S.R., “Structural Analysis of 

‘Flexible’ Liposome Formulations: New Insights into the 

Skin-Penetrating Ability of Soft Nanostructures,” Soft 

Matter 8(40), 10226 (2012). [CHRNS]

Oh, H., Ketner, A.M., Heymann, R., Kesselman, E., 

Danino, D., Falvey, D.E., Raghavan, S.R., “A Simple 

Route to Fluids with Photo-Switchable Viscosities 

based on a Reversible Transition between Vesicles and 

Wormlike Micelles,” Soft Matter 9(20), 5025 (2013). 

Olds, D.P., Duxbury, P.M., Kiel, J.W., Mackay, M.E., 

“Percolating Bulk Heterostructures from Neutron 

Reflectometry and Small-Angle Scattering Data,” 

Phys. Rev. E 86(6), 061803 (2012). [CHRNS]

Omenya, F., Chernova, N.A., Wang, Q., Zhang, 

R., Whittingham, M.S., “The Structural and 

Electrochemical Impact of Li and Fe Site Substitution in 

LiFePO4

,” Chem. Mater. 25(13), 2691 (2013).

Page, K.A., England, D., Texter, J., “Capturing Nanoscale in 

Network Gels by Microemulsion Polymerization,” ACS 

Macro. Letters 1(12), 1398 (2012). [CHRNS]

Pajerowski, D.M., Rotundo, C.R., Lynn, J.W., Birgeneau, 

R.J., “Magnetic Neutron Diffraction Study of 

Ba(Fe1-xCox)2As2 Critical Exponents through the 

Tricritical Doping,” Phys. Rev. B 87(13), 134507 

(2013).

Pajerowski, D.M., Garlea, V.O., Knowles, E.S., Andrus, 

M.J., Dumont, M.F., Calm, Y.M., Nagler, S.E., Tong, 

X., Talham, D.R., Meisel, M.W., “Magnetic Neutron 

Scattering of Thermally Quenched K-Co-Fe Prussian 

Blue Analogue Photomagnet,” Phys. Rev. B 86(5), 

054431 (2012).

Pajerowski, D.M., Zakrzewksi, B.M., Ravel, B., 

“X-ray Structural Studies of Prussian Blue Analog 

Heterostructures on Poly(ethylene terephthalate) 

Supports,” Thin Solid Films 526, 34 (2012).

Pan, C., Li, H., Akgun, B., Satija, S.K., Zhu, Y., Xu, D., 

Ortiz, J., Gersappe, D., Rafailovich, M.H., “Enhancing 

the Efficiency of Bulk Heterojunction Solar Cells via 

Templated Self-Assembly,” Macromolecules 46(5), 

1812 (2013).

Pan, J., Heberle, F.A., Tristram-Nagle, S., Szymanski, M., 

Koepfinger, M., Katsaras, J., Kučerka, N., “Molecular 

Structures of Fluid Phase Phosphatidylglycerol Bilayers 

as Determined by Small Angle Neutron and X-ray 

Scattering,” Biochem. Biophys. Acta 1818, 2135 

(2012). [CHRNS]

Pandey, A., Ueland, B.G., Yeninas, S., Kreyssig, A., 

Sapkota, A., Zhao, Y., Helton, J.S., Lynn, J.W., 

McQueeny, R.J., Furukawa, Y., Goldman, A.I., 

Johnston, D.C., “Coexistence of Half-Metallic 

Itinerant Ferromagnetism with Local-Moment 

Antiferromagnetism in Ba0.60K0.40Mn2As2,” Phys. Rev. 

Lett. 111(4), 047001 (2013).
72 NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY – NIST CENTER FOR NEUTRON RESEARCH PUBLICATIONS

Pandey, A., Khan, A.S., Kim, E.-Y., Choi, S.-H., 

Gnäupel-Herold, T., “Experimental and Numerical 

Investigations of Yield Surface, Texture, and 

Deformation Mechanisms in AA5754 Over Low to 

High Temperatures and Strain Rates,” Int. J. Plasticity 

41, 165 (2013). 

Pangelis, S., Olsen, S.R., Scherschlight, J., Leão, J.B., 

Pullen, S.A., Dender, D., Hester, J.R., Imperia, 

P., “Safety Interlock and Vent System to Alleviate 

Potentially Dangerous Ice Blockage of Top-loading 

Cryostat Sample Sticks.,” J. Appl. Crystallogr., in press. 

[CHRNS]

Patterson, J.P., Kelley, E.G., Murphy, R.P., Moughton, A.O., 

Robin, M.P., Lu, A., Colombani, O., Chassenieux, C., 

Cheung, D., Sullivan, M.O., Epps, III, T.H., O’Reilly, 

R.K., “Structural Characterization of Amphiphilic 

Homopolymer Micelles using Light Scattering, SANS, 

and Cryo-TEM,” Macromolecules, in press.

Patterson, J.P., Cotanda, P., Kelley, E.G., Moughton, 

A.O., Lu, A., Epps, III, T.H., O’Reilly, R.K., 

“Catalytic Y-Tailed Amphiphilic Homopolymers 

- Aqueous Nanoreactors for High Activity, Low 

Loading SCS Pincer Catalysts,” Polym. Chem. 4(6), 

2033 (2013).

Paul, R.L., “Determination of Arsenic in Food and Dietary 

Supplement Standard Reference Materials by Neutron 

Activation Analysis,” J. Radioanal. Nucl. Ch., in press.

Paul, R.L., Lindstrom, R.M., “Preparation and Certification 

of Hydrogen in Titanium Alloy Standard Reference 

Materials,” Metall. Trans. A 43(12), 4888 (2012).

Peng, J., Xu, W., Yan, Y., Yang, J., Fu, L., Kang, H., He, 

J., “Study on Lattice Dynamics of filled Skutterudites 

InxYbyCo4Sb12,” J. Appl. Phys. 112(2), 024909 (2012).

Peng, Y., Krungleviciute, V.N., Eryazici, I., Hupp, J.T., Farha, 

O.K., Yildirim, T., “Methane Storage in Metal-Organic 

Frameworks: Current Records, Surprise Findings, and 

Challenges,” J. Am. Chem. Soc., in press.

Peng, Y., Srinivas, G., Wilmer, C.E., Eryazici, I., Snurr, R.Q., 

Hupp, J.T., Yildirim, T., Farha, O.K., “Simultaneously 

High Gravimetric and Volumetric Methane Uptake 

Characteristics of the Metal-Organic Framework NU111,” Chem. Commun. 49(29), 2992 (2013).

Perez Mendez, M., Hammouda, B., “SAXS and SANS 

Investigation of Synthetic Cholesteric Liquid-Crystal 

Polymers for Biomedical Applications,” J. Mtls. Sci. Eng. 

B 3(2), 104 (2013). [CHRNS]

Petzetakis, N., Robin, M.P., Patterson, J.P., Kelley, E.G., 

Cotanda, P., Bomans, P.H.H., Sommerdijk, N.A.J., 

Dove, A.P., Epps, III, T.H., O’Reilly, R.K., “Hollow 

Block Copolymer Nanoparticles through a Spontaneous 

One-Step Structural Reorganization,” ACS Nano 7(2), 

1120 (2013).

Pimpinella, R.E., Zhang, D., McCartney, M.R., Smith, D.J., 

Krycka, K.L., Kirby, B.J., O’Dowd, B.J., Sonderhouse, 

L., Leiner, J., Liu, X., Dobrowolska, M., Furdyna, J.K., 

“Magnetic Properties of GaAs/Fe Core/Shell Nanowires,” 

J. Appl. Phys. 113(17), 17B5201 (2013). [CHRNS]

Polsky, Y., Anovitz, L.M., Bingham, P., Carmichael, J., 

“Application of Neutron Imaging to Investigate 

Flow Through Fractures for EGS,” in “Proceedings, 

Thirty-Eighth Workshop on Geothermal Reservoir 

Engineering,” (Stanford Geothermal Workshop, 

February 2013, Stanford, CA) SGP-TR-198 (2013).

Pratt, D.K., Chang, S., Tain, W., Taskin, A.A., Ando, 

Y Zarestky, J.L., Kreyssig, A., Goldman, A.I., 

McQueeney, R., “Checkerboard to Stripe Charge 

Ordering Transition in TbBaFe2O5,” Phys. Rev. B 

87(4), 045127 (2013).

Purewal, J., Keith, J.B., Ahn, C.C., Brown, C.M., Tyagi, 

M., Fultz, B., “Hydrogen Diffusion in Potassium 

Intercalated Graphite Studied by Quasielastic Neutron 

Scattering,” J. Chem. Phys. 137(22), 224704 (2012). 

[CHRNS]

Qajar, A., Peer, M., Rajagopalan, R., Liu, Y., Brown, 

C., Foley, H.C., “Surface Compression of Light 

Adsorbates Inside Microporous PFA-Derived 

Carbons,” Carbon 60, 538 (2013).

Qian, K.K., Zhou, W., Xu, X., Udovic, T.J., 

“Characterization of Medicinal Compounds Confined 

in Porous Media by Neutron Vibrational Spectroscopy 

and First-Principles Calculations: A Case Study with 

Ibuprofen,” Pharm. Res. 29(9), 2432 (2012).

Rao, X., Cai, J., Yu, J., He, Y., Wu, C., Zhou, W., 

Yildirim, T., Chen, B., Qian, G., “A Microporous 

Metal-Organic Framework with Both Open Metal 

and Lewis Basic Pyridyl Sites for High C2H2 and 

CH4 Storage at Room Temperature,” Chem. 

Commun., in press.

Ratcliff, II, W., Yamani, Z., Anbusathaiah, V., Gao, 

T.R., Kienzle, P.A., Cao, H., Takeuchi, I., “ElectricField-Controlled Antiferromagnetic Domains in 

Epitaxial BiFeO3 Thin Films Probed by Neutron 

Diffraction,” Phys. Rev. B 87(14), 140405 (2013).
2013 ACCOMPLISHMENTS AND OPPORTUNITIES 73PUBLICATIONS

Reents-Budet, D., Stanley, G., Bishop, R.L., Blackman, 

M.J., “Identity and Interaction: Ceramic Styles 

and Social History of the Ik’ Polity, Guatemala,” in 

“Motul de San José: politics, history and economy in 

a Maya polity,” edited by Foias, A.E. and Emery, K.F., 

(University of Florida Press, Gainesville) 67 (2012). 

Reents-Budet, D., Bishop, R.L., “Classic Maya Painted 

Ceramics: Artisans, Workshops, and Distribution,” 

in “Ancient Maya Art at Dumbarton Oaks,” edited 

by Pillsbury, J., Doutriaux , M., Ishihara-Brito, R., 

Tokovinine, A., ( Pre-columbian Art at Dumbarton 

Oaks, Number 4. Dumbarton Oaks Research 

Library and Collection, Washington, D.C.) (2012).

Rehm, C., Barker, J., Bouwman, W.G., Pynn, R., “DCD 

USANS and SESANS: a Comparison of Two Neutron 

Scattering Techniques Applicable for the Study of 

Large-Scale Structures,” J. Appl. Crystallogr. 46(2), 354 

(2013). [CHRNS]

Reyes-Ortiz, V., Heins, R.A., Cheng, G., Kim, E.Y., 

Vernon, B.C., Elandt, R.B., Adams, P.D., Sale, K.L., 

Hadi, M.Z., Simmons, B.A., Kent, M.S., TullmanErcek, D., “Addition of a Carbohydrate-binding 

Module Enhances Cellulase Penetration into Cellulose 

Substrates,” Biotechnol Biofuels 6, 93 (2013).

Rikkou-Kalourkoti, M., Patrickios, C.S., “Synthesis 

and Characterization of End-Linked Amphiphilic 

Copolymer Conetworks Based on a Novel Bifunctional 

Cleavable Chain Transfer Agent,” Macromolecules 

45(19), 7890 (2012).

Ro, H.W., Akgun, B., O’Connor, B.T., Hammond, M., 

Kline, R.J., Snyder, C.R., Satija, S.K., Ayzner, A.L., 

Toney, M.F., Soles, C.L., DeLongchamp, D.M., 

“Poly(3-hexylthiophene) and [6,6]-Phenyl-C61-butyric 

Acid Methyl Ester Mixing in Organic Solar Cells,” 

Macromolecules 45(16), 6587 (2012).

Rubinson, K.A., Meuse, C.W., “Deep Hydration: 

Poly(ethylene glycol) Mw 2000-8000 Da Probed by 

Vibrational Spectrometry and Small-Angle Neutron 

Scattering and Assignment of ∆G° to Individual Water

Layers,” Polymer 54(2), 709 (2013). [CHRNS]

Rubinson, K.A., Pokalsky, C., Krueger, S., Prochaska, 

L.J., “Structure Determination of Functional 

Membrane Proteins using Small-Angle Neutron 

Scattering (SANS) with Small, Mixed-Lipid 

Liposomes: Native Beef Heart Mitochondrial 

Cytochrome c Oxidase Forms Dimers,” Protein J. 

32(1), 27 (2013). [CHRNS]

Ruppert, L.F., Sakurovs, R., Blach, T.P., He, L., Melnichenko, 

Y.B., Mildner, D.F.R., Alcantar-Lopez, L., “A USANS/

SANS Study of the Accessibility of Pores in the Barnett 

Shale to Methane and Water,” Energ. Fuel. 27(2), 772 

(2013). [CHRNS]

Sadakane, K., Horikawa, Y., Nagao, M., Seto, H., “The 

Effect of Tetraphenylphosphonium Chloride on Phase 

Behavior and Nanoscale Structures in a Mixture of 

D2O and 3-Methylpyridine,” Chem. Lett. 41(10), 1075 

(2012).

Satsoura, D., Kučerka, N., Shivakumar, S., Pencer, J., 

Groffiths, C., Leber, B., Andrews, D.W., Katsaras, 

J., Fradin, C., “Interaction of the Full-Length Bax 

Protein with Biomimetic Mitochondrial Liposomes: 

A Small-Angle Neutron Scattering and Fluorescence 

Study,” Biochim. Biophys. Acta, Biomembr. 1818(3), 

384 (2013). [CHRNS]

Savary, L., Ross, K.A., Gaulin, B.D., Ruff, J.P.C., Balents, L., 

“Order by Quantum Disorder in Er2Ti2O7,” Phys. Rev. 

Lett. 109(16), 167201 (2012). [CHRNS]

Selamet, O.F., Pasaogullari, U., Spernjak, D., Hussey, D.S., 

Jacobson, D.L., Mat, M.D., “Two-phase Flow in a 

Proton Exchange Membrane Electrolyzer Visualized in 

situ by Simultaneous Neutron Radiography and Optical 

Imaging,” Int. J. Hydrogen Energ. 38(14), 5823 (2013).

Shenoy, S.S., Nanda, H., Lösche, M., “Membrane 

Association of the PTEN Tumor Suppressor: 

Electrostatic Interaction with PhosphatidylserineContaining Bilayers and Regulatory Role of the 

C-Terminal Tail,” J. Struct. Biol. 180(3), 394 (2012).

Shin, N., Kang, J., Richter, L.J., Prabhu, V.M., Kline, R.J., 

Fischer, D.A., DeLongchamp, D.M., Toney, M.F., Satija, 

S.K., Gundlach, D.J., Purushothaman, B., Anthony, 

J.E., Yoon, D.Y., “Vertically Segregated Structure 

and Properties of Small Molecule-Polymer Blend 

Semiconductors for Organic Thin-Film Transistors,” 

Adv. Funct. Mater. 23(3), 366 (2013).

Siegel, J.B., Stefanopoulou, A.G., Hagans, P., Ding, 

Y., Gorsich, D., “Expansion of Lithium Ion 

Pouch Cell Batteries: Observations from Neutron 

Imaging,” J. Electrochem. Soc. 160(8), A1031 

(2013).

Simmons, D.S., Cicerone, M.T., Zhong, Q., Tyagi, M., 

Douglas, J.F., “Generalized Localization Model of 

Relaxation in Glass-forming Liquids,” Soft Matter 8(45), 

11455 (2012). [CHRNS]
74 NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY – NIST CENTER FOR NEUTRON RESEARCH PUBLICATIONS

Singh, D.K., Lee, Y., “Nonconventional Spin Glass Transition 

in a Chemically Ordered Pyrochlore,” Phys. Rev. Lett. 

109(24), 247201 (2012). [CHRNS]

Singh, D.K., Thamizhavel, A., Lynn, J.W., Dhar, S.K., 

Hermann, T., “Multiple Magnetic Structures of 

Correlated Ce-ions in Intermetallic CeAu2Ge2,” Phys. 

Rev. B 86(6), 060405 (2012). [CHRNS]

Snow, W.M., Anderson, E., Barrón-Palos, L., Bass, 

C.D., Bass, T.D., Crawford, B.E., Fry, J., Gan, K., 

Heckel, B.R., Luo, D., Malone, R.C., Markoff, 

D.M., Micherdzinska, A.M., Mumm, H.P., Nico, 

J.S., Opper, A.K., Penn, S., Santra, S., Sarsour, 

M., Sharapov, E.I., Swanson, H.E., Van Sciver, 

S., Walbridge, S.B., Zhumabekova, V., “Parity 

Violating Neutron Spin Rotation in 4

He and H,” Il 

Nuovo Cimento 35(4), 57 (2012).

Song, Y., Carr, S.V., Lu, X., Zhang, C., Sims, Z.C., 

Luttrell, N.F., Chi, S., Zhao, Y., Lynn, J.W., Dai, P., 

“Uniaxial Pressure Effect on Structural and Magnetic 

Phase Transitions in NaFeAs and its Comparison 

with As-Grown and Annealed BaFe2As2,” Phys. Rev. 

B 87(18), 184511 (2013).

Sorte, E.G., Bowman, Jr., R.C., Majzoub, E.H., 

Verkuijlen, M.H.W., Udovic, T.J., Conradi, M.S., 

“Mobile Species in NaAlH4,” J. Phys. Chem. C 

117(16), 8015 (2013).

Srinivas, G., Travis, W., Ford, J., Wu, H., Guo, Z.-X., 

Yildirim, T., “Nanoconfined Ammonia Borane in 

a Flexible Metal-Organic Framework Fe-MIL-53: 

Clean Hydrogen Release with Fast Kinetics,” J. 

Mater. Chem. A 1(13), 4167 (2013).

Stalick, J.K., Wang, K., Waterstrat, R.M., “The 

Crystal Structure and Phase Transition of 

Hf2Pt3,” J. Phase Equilib. Diff. 1, (1) (2013).

Starowicz, P., Schwab, H., Goraus, J., Zajdel, P., Forster, F., 

Rak, J.R., Green, M.A., Vobornik, I., Reinert, F., “A 

Flat Band at the Chemical Potential of a Fe1.03Te0.94S0.06

Superconductor Observed by Angle-Resolved 

Photoemission Spectroscopy,” J. Phys.: Condens. 

Matter 25(19), 195701 (2013).

Stock, C., Broholm, C., Zhao, Y., Demmel, F., Kang, H.J., 

Rule, K.C., Petrovic, C., “Magnetic Field Splitting 

of the Spin Resonance in CeCoIn5,” Phys. Rev. Lett. 

109(16), 167207 (2012). [CHRNS]

Stock, C., Broholm, C., Demmel, F., Van Duijn, J., 

Taylor, J.W., Kang, H.J., Hu, R., Petrovic, C., 

“From Incommensurate Correlations to Mesoscopic 

Spin Resonance in YbRh2Si2,” Phys. Rev. Lett. 

109(12), 127201 (2012).

Stock, C., Gehring, P.M., Hiraka, H., Swainson, I., Xu, G., 

Ye, Z.-G., Luo, H., Li, J.-F., Viehland, D., “Evidence 

for Anisotropic Polar Nanoregions in Relaxor 

Pb(Mg1/3Nb2/3)O3: A Neutron Study of the Elastic 

Constants and Anomalous TA Phonon Damping 

in PMN,” Phys. Rev. B 86(10), 104108 (2012). 

[CHRNS]

Subramanian, D., Boughter, C.T., Klauda, J.B., 

Hammouda, B., Anisimov, M.A., “Mesoscale 

Inhomogeneities in Aqueous Solutions of Small 

Amphiphilic Molecules,” Faraday Discuss., in press. 

[CHRNS]

Swain, M., Singh, S., Basu, S., Gupta, M., “Effect of 

Interface Morphology on Intermetallics Formation upon 

Annealing of Al-Ni Multilayer,” J. Alloy Compd., in 

press.

Tang, Z., Tan, Y., Wu, H., Gu, Q., Zhou, W., Jensen, C.M., 

Yu, X., “Metal Cation-Promoted Hydrogen Generation 

in Activated Aluminium Borohydride Ammoniates,” 

Acta Mater. 61(13), 4787 (2013).

Tarasevich, B.J., Perez-Salas, U., Masica, D.L., Philo, J., 

Kienzle, P., Krueger, S., Majkrzak, C.F., Gray, J.L., 

Shaw, W.J., “Neutron Reflectometry Studies of the 

Adsorbed Structure of the Amelogenin, LRAP,” J. Phys. 

Chem. B 117(11), 3098 (2013).

Tong, P., Louca, D., Wang, G., Liaw, P.K., Yokoyama, Y., 

Llobet, A., Kawaji, H., Qiu, Y., Shi, Y., “Structural 

Irreversibility in Enhanced Brittleness under Fatigue in 

Zr-Based Amorphous Solids,” Metals 2(4), 529 (2012). 

[CHRNS]

Tong, X., Jiang, C.Y., Lauter, V., Ambaye, H., Brown, D., 

Crow, L., Gentile, T.R., Goyette, R., Lee, W.T., Parizzi, 

A., Robertson, J.L., “In situ polarized 3

He System for 

the Magnetism Reflectometer at the Spallation Neutron 

Source,” Rev. Sci. Instrum. 83(7), 075101 (2012).

Toppozini, L., Armstrong, C.L., Barrett, M.A., Zheng, S., 

Luo, L., Nanda, H., García Sakai, V., Rheinstädter, 

M.C., “Partitioning of Ethanol into Lipid Membranes 

and its Effect on Fluidity and Permeability as seen by 

X-ray and Neutron Scattering,” Soft Matter 8, 11839 

(2012). [CHRNS]
2013 ACCOMPLISHMENTS AND OPPORTUNITIES 75PUBLICATIONS

Tung, W.-S., Bird, V., Composto, R.J., Clarke, N., Winey, 

K.I., “Polymer Chain Conformations in CNT/PS 

Nanocomposites from Small Angle Neutron Scattering,” 

Macromolecules 46(13), 5345 (2013). [CHRNS]

Udovic, T.J., Verdal, N., Rush, J.J., De Vries. D.J., 

Hartman, M.R., Vajo, J.J., Gross, A.F., Skripov, A.V., 

“Mapping Trends in the Reorientational Mobilities of 

Tetrahydroborate Anions via Neutron-Scattering FixedWindow Scans,” J. Alloy Compd., in press. [CHRNS]

Vaish, A., Silin, V., Walker, M.L., Steffens, K.L., Krueger, 

S., Yeliseev, A.A., Gawrisch, K., Vanderah, D.J., “A 

Generalized Strategy for Immobilizing Uniformly 

Oriented Membrane Proteins at Solid Interfaces,” 

Chem. Commun. 49, 2685 (2013). 

Van Dyk, A., Nakatani, A., “Shear Rate-Dependent Structure 

of Polymer-Stabilized TiO2 Dispersions,” J. Coating. 

Tech. Res. 10(3), 297 (2013). [CHRNS]

Verdal, N., Udovic, T.J., Zhou, W., Rush, J.J., De Vries, 

D.J., Hartman, M.R., “Vibrational Spectroscopic Study 

of Subtle Phase Transitions in Alkali Borohydrides: 

Comparison with First-Principles Calculations,” J. Phys. 

Chem. C 117(2), 876 (2013).

Verdal, N., Udovic, T.J., Rush, J.J., Wu, H., Skripov, A.V., 

“Evolution of the Reorientational Motions of the 

Tetrahydroborate Anions in Hexagonal LiBH4-LiI 

Solid Solution by High-Q Quasielastic Neutron 

Scattering,” J. Phys. Chem. C 117(23), 12010 

(2013). [CHRNS]

Wagman, J.J., Van Gastel, G., Ross, K.A., Yamani, Z., 

Zhao, Y., Qiu, Y., Copley, J.R.D., Kallin, A.B., 

Mazurek, E., Carlo, J.P., Dabkowska, H.A., Gaulin, 

B.D., “Two-Dimensional Incommensurate and Three 

Dimensional Commensurate Magnetic Order and 

Fluctuations in La2-xBaxCuO4,” Phys. Rev. B 88(1), 

014412 (2013). [CHRNS]

Wang, H.-W., Wesolowski, D.J., Proffen, T.E., Vlcek, L., 

Wang, W., Allard, L.F., Kolesnikov, A.I., Feygenson, M., 

Anovitz, L.M., Paul, R.L., “Structure and Stability of 

SnO2 Nanocrystals and Surface-Bound Water Species,” 

J. Am. Chem. Soc. 135(18), 6885 (2013).

Wang, R., Yang, C., Fan, M., Wu, M., Wang, C., Yu, X., 

Zhu, J., Zhang, J., Li, G., Huang, Q., Chen, D., Jin, 

T., Kamiyama, T., Liao, F., Lin, J., “Phase Relationship 

of the TbO1.81-Mn3O4-Fe2O3 System Synthesized at 

1200 °C,” J. Alloy Compd. 554, 385 (2013).

Watson, B.J., Hammouda, B., Briber, R.M., Hutcheson, 

S.W., “Influence of Organic Liquids on the 

Nanostructure of Precipitated Cellulose,” J. Appl. 

Polym. Sci. 127(4), 2620 (2013). [CHRNS]

Watson, M.C., Curtis, J.E., “Rapid and Accurate 

Calculation of Small-Angle Scattering Profiles using 

the Golden Ratio,” J. Appl. Cryst., in press.

Weigandt, K.M., White, N., Chung, D., Ellingson, E., 

Wang, Y., Fu, X., Pozzo, D.C., “Fibrin Clot Structure 

and Mechanics Associated with Specific Oxidation 

of Methionine Residues in Fibrinogen,” Biophys. J. 

103(11), 2399 (2012). [CHRNS]

Welch, C., Labouriau, A., Hjelm, R., Orler, B., Johnston, 

C., Kim, Y.S., “Nafion in Dilute Solvent Systems: 

Dispersion or Solution?,” ACS Macro Letters 1, 1403 

(2012). [CHRNS]

Wignall, G.D., Littrell, K.C., Heller, W.T., Melnichenko, 

Y.B., Bailey, K.M., Lynn, G.W., Myles, D.A., Urban, 

V.S., Buchanan, M.V., Selby, D.L., Butler, P.D., “The 

40 m General Purpose Small-Angle Neutron Scattering 

Instrument at Oak Ridge National Laboratory,” J. Appl. 

Crystallogr. 45(5), 990 (2012).

Wilmer, C.E., Farha, O.K., Yildirim, T., Eryazici, I., 

Krungleviciute, V., Sarjeant, A.A., Snurr, R.Q., 

Hupp, J.T., “Gram-Scale, High-Yield Synthesis of 

a Robust Metal-Organic Framework for Storing 

Methane and Other Gases,” Energy Environ. Sci. 

6(4), 1158 (2013).

Wong-Ng, W., Kaduk, J.A., Wu, H., Suchomel, M., 

“Synchrotron X-Ray Studies of Metal-Organic 

Framework M2(2,5-Dihydroxyterephthalate), 

M=(Mn, Co, Ni, Zn) (MOF74),” Powder Diffr. 

27(4), 256 (2012).

Wong-Ng, W., Kaduk, J.A., Huang, Q., Espinal, 

L., Li, L., Burress, J.W., “Investigation of NaY 

Zeolite with Adsorbed CO2 by Neutron Powder 

Diffraction,” Micropor. Mesopor. Mat. 172, 95 

(2013).

Wright, N.T., Raththagala, M., Hemmis, C.W., Edwards, 

S., Curtis, J.E., Krueger, S., Schildbach, J.F., “Solution 

Structure and Small Angle Scattering Analysis of Tral 

(381-569),” Proteins 80(9), 2250 (2012). [CHRNS]
76 NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY – NIST CENTER FOR NEUTRON RESEARCH PUBLICATIONS

Wu, B., Liu, Y., Li, X., Mamontov, E., Kolesnikov, A.I., 

Diallo, S.O., Do, C., Porcar, L., Hong, K., Smith, S.C., 

Liu, L., Smith, G.S., Egami, T., Chen, W.-R., “ChargeDependent Dynamics of a Polyelectrolyte Dendrimer 

and Its Correlation with Invasive Water,” J. Am. Chem. 

Soc. 135(13), 5111 (2013). [CHRNS]

Wu, B., Chen, W.-R., Egami, T., Li, X., Liu, Y., Wang, Y., 

Do, C., Porcar, L., Hong, K., Liu, L., Smith, G.S., 

Smith, S.C., “Molecular Dynamics and Neutron 

Scattering Study of the Dependence of Polyelectrolyte 

Dendrimer Conformation on Counterion Behavior,” J. 

Chem. Phys. 137(6), 064902 (2012).

Wu, H., Chua, Y.S., Krungleviciute, V., Tyagi, M., Chen, P., 

Yildirim, T., Zhou, W., “Unusual and Highly Tunable 

Missing-Linker Defects in Zirconium Metal-Organic 

Framework UiO-66 and Their Important Effects on 

Gas Adsorption,” J. Am. Chem. Soc. 135(28), 10525 

(2013). [CHRNS]

Wu, H., Yildirim, T., Zhou, W., “Exceptional Mechanical 

Stability of Highly Porous Zirconium Metal-Organic 

Framework UiO-66 and its Important Implications,” 

J. Phys. Chem. Lett. 4(6), 925 (2013).

Xie, W., Hitchcock, D.A., Kang, H.J., He, J., Tang, X., 

Laver, M., Hammouda, B., “The Microstructure 

Network and Thermoelectric Properties of Bulk 

(BiSb)2Te3,” Appl. Phys. Lett. 101(11), 113902 (2012). 

[CHRNS]

Xu, L., Zhang, Q., Hou, G., Chen, P., Li, G., Pajerowski, 

D.M., Dennis, C.L., “Syntheses, Structures, and 

Magnetic Properties of Salen Type Cu-Gd Dimer 

and Hexamer Complexes with Strong Ferromagnetic 

Interactions,” Polyhedron 52, 91 (2013).

Xu, Z., Wen, J., Berlijn, T., Gehring, P.M., Stock, 

C., Stone, M.B., Ku, W., Gu, G., Shapiro, S.M., 

Birgeneau, R.J., Xu, G., “Thermal Evolution of the 

Full Three-Dimensional Magnetic Excitations in the 

Multiferroic BiFeO3,” Phys. Rev. B 86(17), 174419 

(2012).

Xu, Z., Wen, J., Zhao, Y., Matsuda, M., Ku, W., Liu, X., 

Gu, G., Lee, D.-H., Birgeneau, R.J., Tranquada, J.M., 

Xu, G., “Temperature-Dependent Transformation of 

the Magnetic Excitation Spectrum on Approaching 

Superconductivity in Fe1+y-x(Ni/Cu)xTe0.5Se0.5,” Phys. Rev. 

Lett. 109(22), 227002 (2012).

Xu, Z., Wen, J., Mamontov, E., Stock, C., Gehring, P.M., 

Xu, G., “Freezing of the Local Dynamics in the Relaxor 

Ferroelectric [Pb(Zn1/3Nb2/3)O3]0.955[PbTiO3]0.045,” Phys. 

Rev. B 86(14), 144106 (2012).

Yamada, T., Yamada, T., Tyagi, M., Nagao, M., Kitagawa, 

H., Yamamuro, O., “Phase Transition and Dynamics 

of Water Confined in Hydroxyethyl Copper Rubeanate 

Hydrate,” J. Phys. Soc. Jpn., in press. [CHRNS]

Yamaguchi, H., Gin, P., Arita, H., Kobayashi, M., Bennett, 

S., Satija, S.K., Asada, M., Koga, T., Takahara, A., 

“Effect of Supercritical Carbon Dioxide on Molecular 

Aggregation States of Side Chains of Semicrystalline 

Poly{2-(perfluorooctyl)ethyl Acrylate} Brush Thin 

Films,” RSC Advances 3(14), 4778 (2013).

Yan, H., Snow, W.M., “New Limit on Possible LongRange Parity-Odd Interactions of the Neutron from 

Neutron-Spin Rotation in Liquid 4

He,” Phys. Rev. 

Lett. 110(8), 082003 (2013).

Yang, Y.B., Chen, X.G., Guo, S., Yan, A.R., Huang, 

Q.Z., Wu, M.M., Chen, D.F., Yang, Y.C., Yang, J.B., 

“Temperature Dependences of Structure and Coercivity 

for Melt-Spun MnBi Compound,” J. Magn. Magn. 

Mater. 330, 106 (2013).

Yao, J., Rudyk, B.W., Brunetta, C.D., Knorr, K.B., Figore, 

H.A., Mar, A., Aitken, J.A., “Mn Incorporation in 

CuInS2 Chalcopyrites: Structure, Magnetism and 

Optical Properties,” Mater. Chem. Phys. 136(2-3), 415 

(2012).

Ye, Q., Gentile, T.R., Anderson, J., Broholm, C., Chen, 

W.C., DeLand, Z., Erwin, R.W., Fu, C.B., Fuller, J., 

Kirchhoff, A., Rodriguez-Rivera, J.A., Thampy, V., 

Walker, T.G., Watson, S., “Wide Angle Polarization 

Analysis with Neutron Spin Filters,” Physics Procedia 

42, 206 (2013). [CHRNS]

Yeon, J., Kim, S.-H., Green, M.A., Bhatti, K.P., Leighton, 

C., Halasyamani, P.S., “Syntheses, Crystal Structures, 

and Characterization of Two New Tl+

-Cu2+-Te6+

Oxides: Tl4CuTeO6 and Tl6CuTe2O10,” J. Solid State 

Chem. 196, 607 (2012).

Yildirim, T., “Ferroelectric Soft Phonons, Charge Density 

Wave Instability, and Strong Electron-Phonon 

Coupling in BiS2 Layered Superconductors: A FirstPrinciples Study,” Phys. Rev. B 87(2), 020506 (2013).
2013 ACCOMPLISHMENTS AND OPPORTUNITIES 77PUBLICATIONS

Yin, L., Lodge, T.P., Hillmyer, M.A., “A Stepwise 

‘Micellization-Crystallization’ Route to Oblate 

Ellipsoidal, Cylindrical, and Bilayer Micelles with 

Polyethylene Cores in Water,” Macromolecules 

45(23), 9460 (2012).

Yoon, I., Ma, H.B., Winholtz, R.A., “Study of the 

Effects of Liquid Fraction and Vapor Volume on the 

Fluctuating Temperature in an Oscillating Heat Pipe 

using Neutron Imaging,” Heat Transfer Research 

44(1), 43 (2013).

Yoon, I., Wilson, C., Borgmeyer, B., Winholtz, R.A., 

Ma, H.B., Jacobson, D.L., Hussey, D.S., “Neutron 

Phase Volumetry and Temperature Observations in 

an Oscillating Heat Pipe,” Int. J. Therm. Sci. 60, 52 

(2012).

Yu, J., Phelan, D., Rodriguez-Rivera, J.A., Podlesnyak, A., 

Louca, D., “Magneto-Polaron Formation and FieldInduced Effects with Dilute Doping in LaCo1-yNiyO3” 

J. Supercond. Nov. Magn., in press. [CHRNS]

Yu, L.L., Jarrett, J.M., Davis, W.C., Kilpatrick, E.L., Oflaz, 

R., Turk, G.C., Leber, D.D., Valentin, L., MorelEspinosa, M., Blount, B.C., “Characterization of 

Perchlorate in a New Frozen Human Urine Standard 

Reference Material,” Anal. Bioanal. Chem. 404(6-7), 

1877 (2012).

Yu, W., Peri, S.R., Akgun, B., Foster, M.D., “Manipulation 

of Polymer/Polymer Interface Width from 

Nonequilibrium Deposition,” ACS Appl. Mater. 

Interfaces 5(8), 2976 (2013).

Yue, M., Liu, D., Huang, Q., Wang, T., Hu, F., Li, J., 

Rao, G., Shen, B., Lynn, J.W., Zhang, J., “Structure 

Evolution and Entropy Change of Temperature and 

Magnetic Field Induced Magneto-Structural Transition 

in Mn1.1Fe0.9P0.76Ge0.24,” J. Appl. Phys. 113(4), 043925 

(2013). 

Zan, G.H., Tan, C., Deserno, M., Lanni, F., Lösche, M., 

“Hemifusion of Giant Unilamellar Vesicles with Planar 

Hydrophobic Surfaces: A Fluorescence Microscopy 

Study,” Soft Matter 8(42), 10877 (2012).

Zeissler, C.J., Forsley, L.P.G., Lindstrom, R.M., Newsome, 

S., Kirk, A., Mosier-Boss, P.A., “Radio-microanalytical 

Particle Measurements Method and Application to 

Fukushima Aerosols Collected in Japan,” J. Radioanal. 

Nucl. Chem. 296(2), 1079 (2013).

Zhang, G., Wu, H., Li, G., Huang, Q., Yang, C., Huang, F., 

Liao, F., Lin, J., “New High Tc Multiferroics KBiFe2O5

with Narrow Band Gap and Promising Photovoltaic 

Effect,” Sci. Rep. 3, 1265 (2013).

Zhang, M., Liu, D., Liu, C., Huang, Q., Wang, S., Zhang, 

H., Yue, M., “Research of the Relationship between 

Phase Transition Process and Magnetic Properties in 

Magnetic Refrigeration Material Mn1.2Fe0.8P0.76Ge0.24,” 

Acta Meteorol. Sin. 49(7), 783 (2013).

Zhao, J., Rotundu, C.R., Marty, K., Matsuda, M., Zhao, Y., 

Setty, C., Bourret-Courchesne, E., Hu, J., Birgeneau, 

R.J., “Effect of Electron Correlations on Magnetic 

Excitations in the Isovalently Doped Iron-Based 

Superconductor Ba(Fe1-xRux)2As2,” Phys. Rev. Lett. 

110(14), 147003 (2013).

Zhao, L.L., Wu, S., Wang, J.K., Hodges, J.P., Broholm, 

C., Morosan, E., “Quasi-two-Dimensional 

Noncollinear Magnetism in the Mott Insulator 

Sr2F2Fe2OS2,” Phys. Rev. B 87(2), 020406 (2013).

Zhou, H.D., Xu, C., Hallas, A.M., Silverstein, H.J., Wiebe, 

C.R., Umegaki, I., Yan, J.Q., Murphy, T.P., Park, J.-

H., Qiu, Y., Copley, J.R.D., Gardner, J.S., Takano, 

Y., “Successive Phase Transitions and Extended SpinExcitation Continuum in the S=1⁄2 Triangular-Lattice 

Antiferromagnet Ba3CoSb2O9,” Phys. Rev. Lett. 

109(26), 267206 (2012). [CHRNS]

Zhu, J., Feng, S., Liu, Q., Zhang, J., Xu, H., Li, Y., Li, X., 

Liu, J., Huang, Q., Zhao, Y., Jin, C., “Temperature and 

Pressure Effects of Multiferroic Bi2NiTiO6 Compound,” 

J. Appl. Phys. 113(14), 143514 (2013).

Zilcha, O., Quinn, G.D., Rowe, J.M., Pierce, D.J., 

“Investigation into the Mechanical Cause of Failure of 

Neutron Guide NG-2 at the NIST Research Reactor,” 

J. Fail. Anal. and Preven. 12(6), 604 (2012).
78 NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY – NIST CENTER FOR NEUTRON RESEARCH INSTRUMENTS AND CONTACTS

Instruments and Contacts (Name, tel. 301-975-xxxx, email)

High resolution powder diffractometer (BT-1):

n J. K. Stalick, 6223, judith.stalick@nist.gov n H. Wu, 2387, hui.wu@nist.gov

n Q. Z. Huang, 6164, qing.huang@nist.gov

n C. M. Brown, 5134, craig.brown@nist.gov

Residual stress diffractometer (BT-8):

• T. Gnaeupel-Herold, 5380, thomas.gnaeupel-herold@nist.gov

30-m SANS instrument (NG-7): 

n Y. Liu, 6235, yun.liu@nist.gov n B. Akgun, 6469, bulent.akgun@nist.gov n P. D. Butler, 2028, paul.butler@nist.gov n J. R. Krzywon, 6650, jkrzywon@nist.gov

30-m SANS instrument (NG-3) (CHRNS):

n B. Hammouda, 3961, hammouda@nist.gov

n S. Krueger, 6734, susan.krueger@nist.gov

n C. Gagnon, 2020, cedric.gagnon@nist.gov

10-m SANS instrument (NG-B) (nSoft): 

n R. Jones, 4624, ronald.jones@nist.gov n K. Weigandt, 8396, kathleen.weigandt@nist.gov n K. Page, 5030, kirt.page@nist.gov n T. Perevozchikova, 8498, tatiana.perevozchikova@nist.gov

USANS, Perfect Crystal SANS (BT-5) (CHRNS):

n D. F. R. Mildner, 6366, david.mildner@nist.gov n M. J. Wasbrough, 6017, matthew.wasbrough@nist.gov n P. D. Butler, 2028, paul.butler@nist.gov

Polarized Beam Reflectometer/Diffractometer (NG-D):

n B. J. Kirby, 8395, brian.kirby@nist.gov

n J. A. Borchers, 6597, julie.borchers@nist.gov n C. F. Majkrzak, 5251, cmajkrzak@nist.gov

MAGIk, Off-Specular Reflectometer (NG-D):

n B. B. Maranville, 6034, brian.maranville@nist.gov

n J. A. Dura, 6251, joseph.dura@nist.gov

Neutron reflectometer-horizontal sample (NG-7): 

n S. K. Satija, 5250, satija@nist.gov

Double-focusing triple-axis Spectrometer (BT-7): 

n Y. Zhao, 2164, yang.zhao@nist.gov

n J. W. Lynn, 6246, jeff.lynn@nist.gov

SPINS, Spin-polarized triple-axis spectrometer (NG-5): 

n L. Harriger, 8360, leland.harriger@nist.gov

Triple-axis spectrometer (BT-4):

n W. Ratcliff, 4316, william.ratcliff@nist.gov

DCS, Disk-chopper time-of-flight spectrometer (NG-4) (CHRNS):

n J. R. D. Copley, 5133, jcopley@nist.gov

n D. Pajerowski, 5660, daniel.pajerowski@nist.gov

n N. Butch, 4863, nicholas.butch@nist.gov n C. M. Brown, 5134, craig.brown@nist.gov

FANS, Filter-analyzer neutron spectrometer (BT-4): 

n T. J. Udovic, 6241, udovic@nist.gov

HFBS, High-flux backscattering spectrometer (NG-2) (CHRNS):

n M. Tyagi, 2046, madhusudan.tyagi@nist.gov

n W. Zhou, 8169, wei.zhou@nist.gov

NSE, Neutron spin echo spectrometer (NG-5) (CHRNS): 

n A. Faraone, 5254, antonio.faraone@nist.gov n M. Nagao, 5505, michihiro.nagao@nist.gov

MACS, Multi-angle crystal spectrometer (BT-9) (CHRNS): 

n J. A. Rodriguez-Rivera, 6019, jose.rodriguez@nist.gov

n Y. Qiu, 3274, yiming.qiu@nist.gov

Cold-neutron prompt-gamma neutron activation analysis (NG-D): 

n R. L. Paul, 6287, rpaul@nist.gov n D. J. O’Kelly, 8793, donna.okelly@nist.gov

Thermal-neutron prompt-gamma activation analysis (VT-5):

n R. L. Paul, 6287, rpaul@nist.gov

n D. J. O’Kelly, 8793, donna.okelly@nist.gov

Cold neutron depth profiling (NG-1):

n R. G. Downing, 3782, gregory.downing@nist.gov

Neutron activation analysis facilities:

n D. J. O’Kelly, 8793, donna.okelly@nist.gov

Neutron Imaging Station (BT-2):

n D. Jacobson, 6207, david.jacobson@nist.gov

n D. Hussey, 6465, daniel.hussey@nist.gov

n M. Arif, 6303, muhammad.arif@nist.gov

Neutron interferometer (NG-7):

n M. Arif, 6303, muhammad.arif@nist.gov n D. Jacobson, 6207, david.jacobson@nist.gov n D. Hussey, 6465, daniel.hussey@nist.gov

Fundamental neutron physics station (NG-6): 

n NG-6M: M. S. Dewey, 4843, mdewey@nist.gov

n NG-6U: H. P. Mumm, 8355, pieter.mumm@nist.gov

n NG-6: J. Nico, 4663, nico@nist.gov

Theory and modeling:

n J. E. Curtis, 3959, joseph.curtis@nist.gov

n T. Yildirim, 6228, taner@nist.gov

INSTRUMENTS UNDER DEVELOPMENT:

vSANS instrument:

n J. G. Barker, 6732, john.barker@nist.gov

n C. G. Glinka, 6242, charles.glinka@nist.gov

CANDOR, White-beam reflectometer/diffractometer:

n F. Heinrich, 4507, frank.heinrich@nist.gov

n C. F. Majkrzak, 5251, charles.majkrzak@nist.gov
2013 ACCOMPLISHMENTS AND OPPORTUNITIES

NIST CENTER FOR NEUTRON RESEARCH CONTACTS

NIST Center for Neutron Research Contacts

Copies of annual reports, facility information, user 

information, and research proposal guidelines are 

available electronically.

Please visit our website: http://www.ncnr.nist.gov

FOR A PAPER COPY OF THIS REPORT:

Steve Kline

301-975-6243

steven.kline@nist.gov

FOR GENERAL INFORMATION ON THE FACILITY:

Rob Dimeo

301-975-6210

robert.dimeo@nist.gov

Dan Neumann

301-975-5252

dan.neumann@nist.gov

FOR INFORMATION ON VISITING THE

FACILITY AND/OR USER ACCESS QUESTIONS:

Julie Keyser

301-975-8200

julie.keyser@nist.gov

Mary Ann FitzGerald

301-975-8200

maryann.fitzgerald@nist.gov

For information on performing

research at the facility:

Bill Kamitakahara

301-975-6878

william.kamitakahara@nist.gov

FACILITY ADDRESS:

NIST Center for Neutron Research

National Institute of Standards and Technology

100 Bureau Drive, Mail Stop 6100

Gaithersburg, MD 20899-6100 USA
NIST CENTER FOR NEUTRON RESEARCH

National Institute of Standards and Technology

100 Bureau Drive, MS 6100

Gaithersburg, MD 20899-6100

www.ncnr.nist.gov