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Mamontov E, Boone C, Frost MJ, Herwig KW, Huegle T, Lin JYY, McCormick B, McHargue W, Stoica AD, Torres P, Turner W. A concept of a broadband inverted geometry spectrometer for the Second Target Station at the Spallation Neutron Source. Rev Sci Instrum 2022; 93:045101. [PMID: 35489951 DOI: 10.1063/5.0086451] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Accepted: 03/11/2022] [Indexed: 06/14/2023]
Abstract
BWAVES is an acronym for Broadband Wide-Angle VElocity Selector spectrometer, indicating that a novel WAVES (Wide-Angle VElocity Selector) device will be used to select the velocity/wavelength of the detected neutrons after they are scattered by the sample. We describe a conceptual design of BWAVES, a time-of-flight broadband inverted-geometry neutron spectrometer for the Second Target Station at the Spallation Neutron Source operated by Oak Ridge National Laboratory. Being the first inverted geometry spectrometer where the energy of the detected neutrons can be chosen by a WAVES device mechanically, irrespective of the limitations imposed by the crystal analyzers or filters, BWAVES will feature a uniquely broad, continuous dynamic range of measurable energy transfers, spanning 4.5 decades. This will enable measurements of both vibrational and relaxational excitations within the same, continuous scattering spectra. Novel approaches that are necessary for the implementation of a WAVES device at the BWAVES spectrometer will result in a spectrometer with the design and characteristics much different from those displayed by the neutron spectrometers in existence today.
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Affiliation(s)
- E Mamontov
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - C Boone
- SNS Second Target Station Project, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - M J Frost
- Neutron Technologies Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - K W Herwig
- SNS Second Target Station Project, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - T Huegle
- Neutron Technologies Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - J Y Y Lin
- SNS Second Target Station Project, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - B McCormick
- SNS Second Target Station Project, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - W McHargue
- Neutron Technologies Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - A D Stoica
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - P Torres
- SNS Second Target Station Project, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - W Turner
- SNS Second Target Station Project, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
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Buck ZN, Torres J, Miskowiec A, Mamontov E, Kaiser H, Hansen FY, Taub H, Tyagi M, Collins L, Herwig KW. Effect of melittin on water diffusion and membrane structure in DMPC lipid bilayers. ACTA ACUST UNITED AC 2018. [DOI: 10.1209/0295-5075/123/18002] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Miskowiec A, Buck ZN, Hansen FY, Kaiser H, Taub H, Tyagi M, Diallo SO, Mamontov E, Herwig KW. On the structure and dynamics of water associated with single-supported zwitterionic and anionic membranes. J Chem Phys 2017; 146:125102. [DOI: 10.1063/1.4978677] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- A. Miskowiec
- Department of Physics and Astronomy and University of Missouri Research Reactor, University of Missouri, Columbia, Missouri 65211, USA
| | - Z. N. Buck
- Department of Physics and Astronomy and University of Missouri Research Reactor, University of Missouri, Columbia, Missouri 65211, USA
| | - F. Y. Hansen
- Department of Chemistry, Technical University of Denmark, IK 207 DTU, DK-2800 Lyngby, Denmark
| | - H. Kaiser
- Department of Physics and Astronomy and University of Missouri Research Reactor, University of Missouri, Columbia, Missouri 65211, USA
| | - H. Taub
- Department of Physics and Astronomy and University of Missouri Research Reactor, University of Missouri, Columbia, Missouri 65211, USA
| | - M. Tyagi
- Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-6102, USA
- Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742, USA
| | - S. O. Diallo
- Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - E. Mamontov
- Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - K. W. Herwig
- Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
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Gallmeier FX, Lu W, Riemer BW, Zhao JK, Herwig KW, Robertson JL. Conceptual moderator studies for the Spallation Neutron Source short-pulse second target station. Rev Sci Instrum 2016; 87:063304. [PMID: 27370444 DOI: 10.1063/1.4953612] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Candidate moderator configurations for a short-pulse second target station (STS) at the Oak Ridge National Laboratory Spallation Neutron Source (SNS) have been identified using a global optimizer framework built around the MCNPX particle transport code. Neutron brightness metrics were selected as the figure-of-merit. We assumed that STS would use one out of six proton pulses produced by an SNS accelerator upgraded to operate at 1.3 GeV proton energy, 2.8 MW power and 60 Hz repetition rate. The simulations indicate that the peak brightness can be increased by a factor of 5 and 2.5 on a per proton pulse basis compared to the SNS first target station for both coupled and decoupled para-hydrogen moderators, respectively. Additional increases by factors of 3 and 2 were demonstrated for coupled and decoupled moderators, respectively, by reducing the area of neutron emission from 100 × 100 mm(2) to 20 × 20 mm(2). This increase in brightness has the potential to translate to an increase of beam intensity at the instruments' sample positions even though the total neutron emission of the smaller moderator is less than that of the larger. This is especially true for instruments with small samples (beam dimensions). The increased fluxes in the STS moderators come at accelerated poison and de-coupler burnout and higher radiation-induced material damage rates per unit power, which overall translate into lower moderator lifetimes. A first effort was undertaken to group decoupled moderators into a cluster collectively positioning them at the peak neutron production zone in the target and having a three-port neutron emission scheme that complements that of a cylindrical coupled moderator.
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Affiliation(s)
- F X Gallmeier
- Instrument and Source Division, Oak Ridge National Laboratory, P.O. Box 2008, MS6466, Oak Ridge, Tennessee 37831, USA
| | - W Lu
- Instrument and Source Division, Oak Ridge National Laboratory, P.O. Box 2008, MS6466, Oak Ridge, Tennessee 37831, USA
| | - B W Riemer
- Instrument and Source Division, Oak Ridge National Laboratory, P.O. Box 2008, MS6466, Oak Ridge, Tennessee 37831, USA
| | - J K Zhao
- Instrument and Source Division, Oak Ridge National Laboratory, P.O. Box 2008, MS6466, Oak Ridge, Tennessee 37831, USA
| | - K W Herwig
- Instrument and Source Division, Oak Ridge National Laboratory, P.O. Box 2008, MS6466, Oak Ridge, Tennessee 37831, USA
| | - J L Robertson
- Instrument and Source Division, Oak Ridge National Laboratory, P.O. Box 2008, MS6466, Oak Ridge, Tennessee 37831, USA
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al-Wahish A, Armitage D, al-Binni U, Hill B, Mills R, Jalarvo N, Santodonato L, Herwig KW, Mandrus D. A new apparatus design for high temperature (up to 950°C) quasi-elastic neutron scattering in a controlled gaseous environment. Rev Sci Instrum 2015; 86:095102. [PMID: 26429475 DOI: 10.1063/1.4929580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Accepted: 08/14/2015] [Indexed: 06/05/2023]
Abstract
A design for a sample cell system suitable for high temperature Quasi-Elastic Neutron Scattering (QENS) experiments is presented. The apparatus was developed at the Spallation Neutron Source in Oak Ridge National Lab where it is currently in use. The design provides a special sample cell environment under controlled humid or dry gas flow over a wide range of temperature up to 950 °C. Using such a cell, chemical, dynamical, and physical changes can be studied in situ under various operating conditions. While the cell combined with portable automated gas environment system is especially useful for in situ studies of microscopic dynamics under operational conditions that are similar to those of solid oxide fuel cells, it can additionally be used to study a wide variety of materials, such as high temperature proton conductors. The cell can also be used in many different neutron experiments when a suitable sample holder material is selected. The sample cell system has recently been used to reveal fast dynamic processes in quasi-elastic neutron scattering experiments, which standard probes (such as electrochemical impedance spectroscopy) could not detect. In this work, we outline the design of the sample cell system and present results demonstrating its abilities in high temperature QENS experiments.
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Affiliation(s)
- Amal al-Wahish
- Department of Physics and Astronomy, The University of Tennessee, Knoxville, Tennessee 37996-1200, USA
| | - D Armitage
- Instrument and Source Design Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37861-6475, USA
| | - U al-Binni
- Department of Physics, Astronomy and Geology, Berry College, Mount Berry, Georgia 30149, USA
| | - B Hill
- Instrument and Source Design Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37861-6475, USA
| | - R Mills
- Instrument and Source Design Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37861-6475, USA
| | - N Jalarvo
- Forschungszentrum Jülich GmbH, Jülich Centre for Neutron Science (JCNS), Outstation at Spallation Neutron Source (SNS), and Chemical and Engineering Materials Division, Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6473, USA
| | - L Santodonato
- Instrument and Source Design Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37861-6475, USA
| | - K W Herwig
- Instrument and Source Design Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37861-6475, USA
| | - D Mandrus
- Department of Physics and Astronomy, The University of Tennessee, Knoxville, Tennessee 37996-1200, USA
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Abstract
We describe the design and current performance of the backscattering silicon spectrometer (BASIS), a time-of-flight backscattering spectrometer built at the spallation neutron source (SNS) of the Oak Ridge National Laboratory (ORNL). BASIS is the first silicon-based backscattering spectrometer installed at a spallation neutron source. In addition to high intensity, it offers a high-energy resolution of about 3.5 μeV and a large and variable energy transfer range. These ensure an excellent overlap with the dynamic ranges accessible at other inelastic spectrometers at the SNS.
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Affiliation(s)
- E Mamontov
- Neutron Scattering Science Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
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Diama A, Matthies B, Herwig KW, Hansen FY, Criswell L, Mo H, Bai M, Taub H. Structure and phase transitions of monolayers of intermediate-length n-alkanes on graphite studied by neutron diffraction and molecular dynamics simulation. J Chem Phys 2009; 131:084707. [PMID: 19725621 DOI: 10.1063/1.3212095] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We present evidence from neutron diffraction measurements and molecular dynamics (MD) simulations of three different monolayer phases of the intermediate-length alkanes tetracosane (n-C(24)H(50) denoted as C24) and dotriacontane (n-C(32)H(66) denoted as C32) adsorbed on a graphite basal-plane surface. Our measurements indicate that the two monolayer films differ principally in the transition temperatures between phases. At the lowest temperatures, both C24 and C32 form a crystalline monolayer phase with a rectangular-centered (RC) structure. The two sublattices of the RC structure each consists of parallel rows of molecules in their all-trans conformation aligned with their long axis parallel to the surface and forming so-called lamellas of width approximately equal to the all-trans length of the molecule. The RC structure is uniaxially commensurate with the graphite surface in its [110] direction such that the distance between molecular rows in a lamella is 4.26 A=sqrt[3a(g)], where a(g)=2.46 A is the lattice constant of the graphite basal plane. Molecules in adjacent rows of a lamella alternate in orientation between the carbon skeletal plane being parallel and perpendicular to the graphite surface. Upon heating, the crystalline monolayers transform to a "smectic" phase in which the inter-row spacing within a lamella expands by approximately 10% and the molecules are predominantly oriented with the carbon skeletal plane parallel to the graphite surface. In the smectic phase, the MD simulations show evidence of broadening of the lamella boundaries as a result of molecules diffusing parallel to their long axis. At still higher temperatures, they indicate that the introduction of gauche defects into the alkane chains drives a melting transition to a monolayer fluid phase as reported previously.
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Affiliation(s)
- A Diama
- Department of Physics and Astronomy and the University of Missouri Research Reactor, University of Missouri, Columbia, Missouri 65211, USA
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Fernandez-Alonso F, Bermejo FJ, McLain SE, Turner JFC, Molaison JJ, Herwig KW. Observation of fractional Stokes-Einstein behavior in the simplest hydrogen-bonded liquid. Phys Rev Lett 2007; 98:077801. [PMID: 17359062 DOI: 10.1103/physrevlett.98.077801] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2006] [Indexed: 05/14/2023]
Abstract
Quasielastic neutron scattering has been used to investigate the single-particle dynamics of hydrogen fluoride across its entire liquid range at ambient pressure. For T>230 K, translational diffusion obeys the celebrated Stokes-Einstein relation, in agreement with nuclear magnetic resonance studies. At lower temperatures, we find significant deviations from the above behavior in the form of a power law with exponent xi=-0.71+/-0.05. More striking than the above is a complete breakdown of the Debye-Stokes-Einstein relation for rotational diffusion. Our findings provide the first experimental verification of fractional Stokes-Einstein behavior in a hydrogen-bonded liquid, in agreement with recent computer simulations [S. R. Becker, Phys. Rev. Lett. 97, 055901 (2006)10.1103/PhysRevLett.97.055901].
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Affiliation(s)
- F Fernandez-Alonso
- ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire OX11 0QX, United Kingdom.
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Hansen FY, Criswell L, Fuhrmann D, Herwig KW, Diama A, Dimeo RM, Neumann DA, Volkmann UG, Taub H. Intramolecular diffusive motion in alkane monolayers studied by high-resolution quasielastic neutron scattering and molecular dynamics simulations. Phys Rev Lett 2004; 92:046103. [PMID: 14995389 DOI: 10.1103/physrevlett.92.046103] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2003] [Indexed: 05/24/2023]
Abstract
Molecular dynamics simulations of a tetracosane (n-C24H50) monolayer adsorbed on a graphite basal-plane surface show that there are diffusive motions associated with the creation and annihilation of gauche defects occurring on a time scale of approximately 0.1-4 ns. We present evidence that these relatively slow motions are observable by high-energy-resolution quasielastic neutron scattering (QNS) thus demonstrating QNS as a technique, complementary to nuclear magnetic resonance, for studying conformational dynamics on a nanosecond time scale in molecular monolayers.
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Affiliation(s)
- F Y Hansen
- Department of Chemistry, Technical University of Denmark, IK 207 DTU, DK-2800 Lyngby, Denmark
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Bordallo HN, Herwig KW, Luther BM, Levinger NE. Quasi-elastic neutron scattering study of dimethyl-sulfoxide–water mixtures: Probing molecular mobility in a nonideal solution. J Chem Phys 2004; 121:12457-64. [PMID: 15606266 DOI: 10.1063/1.1823391] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The translational and rotational motions of water and dimethyl sulfoxide, [DMSO, (CH(3))(2)SO] have been investigated using quasi-elastic neutron scattering. Water-DMSO mixtures at five DMSO mole fractions, chi(DMSO), ranging from 0 to 0.75, were measured. Hydrogen-deuterium substitution was used to extract independently the water proton dynamics (d-DMSO-H(2)O), the DMSO methyl proton dynamics (h-DMSO-D(2)O) and to obtain background corrections (d-DMSO-D(2)O). The translational diffusion of water slows down significantly compared to bulk water at all chi(DMSO)>0. The rotational time constant for water exhibits a maximum at chi(DMSO)=0.33 that corresponds to the observed maximum of the viscosity of the mixture. Data for DMSO can be analyzed in terms of a relatively slow tumbling of the molecule about its center-of-mass in conjunction with random translational diffusion. The rotational time constant for this motion exhibits some dependence on chi(DMSO), while the translational diffusion constant shows no clear variation for chi(DMSO)>0. The results presented reinforce the idea that due to the stronger associative nature of DMSO, DMSO-water aggregates are formed over the whole composition range, disturbing the tetrahedral natural arrangement of the water molecules. As a consequence adding DMSO to water causes a drastic slowing down of the dynamics of the water molecule, and vice versa.
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Affiliation(s)
- H N Bordallo
- Hahn-Meitner-Institut, SFl Glienicker Strasse, 100, D-14109 Berlin, Germany.
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Herwig KW, Fuhrmann D, Criswell L, Taub H, Hansen, F, Dimeo R, Neumann DA. Dynamics of intermediate-length alkane films absorbed on graphite. ACTA ACUST UNITED AC 2000. [DOI: 10.1051/jp4:2000731] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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Popovici M, Herwig KW, Berliner R, Yelon WB, Groza L. High resolution neutron scattering with bent monochromators made of commercial silicon wafers. GNER 1999. [DOI: 10.1080/10238169908200044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Herwig KW, Wu Z, Dai P, Taub H, Hansen FY. Quasielastic neutron scattering and molecular dynamics simulation studies of the melting transition in butane and hexane monolayers adsorbed on graphite. J Chem Phys 1997. [DOI: 10.1063/1.474881] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Herwig KW, Matthies B, Taub H. Solvent effects on the monolayer structure of long n-alkane molecules adsorbed on graphite. Phys Rev Lett 1995; 75:3154-3157. [PMID: 10059508 DOI: 10.1103/physrevlett.75.3154] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Herwig KW, Newton JC, Taub H. Structure and growth of butane films adsorbed on graphite. Phys Rev B Condens Matter 1994; 50:15287-15297. [PMID: 9975881 DOI: 10.1103/physrevb.50.15287] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Herwig KW, Sokol PE, Snow WM, Blasdell RC. Deviations from the impulse approximation in liquid 4He: Momentum-transfer dependence. Phys Rev B Condens Matter 1991; 44:308-316. [PMID: 9998248 DOI: 10.1103/physrevb.44.308] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Kellogg GJ, White JW, Herwig KW, Sokol PE. High energy inelastic neutron scattering from physisorbed hydrogen in cesium intercalated graphite. J Chem Phys 1990. [DOI: 10.1063/1.459439] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Herwig KW, Sokol PE, Sosnick TR, Snow WM, Blasdell RC. Density dependence of the momentum distribution in normal liquid 4He. Phys Rev B Condens Matter 1990; 41:103-110. [PMID: 9992743 DOI: 10.1103/physrevb.41.103] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Herwig KW, Gavilano JL, Schmidt MC, Simmons RO. Density dependence of the single-particle kinetic energy of solid hydrogen. Phys Rev B Condens Matter 1990; 41:96-102. [PMID: 9992742 DOI: 10.1103/physrevb.41.96] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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