High energy inelastic neutron scattering from physisorbed hydrogen in cesium intercalated graphite

Journal Article · Thu Nov 15 00:00:00 EST 1990 · Journal of Chemical Physics; (USA)

DOI:https://doi.org/10.1063/1.459439· OSTI ID:6057065

Kellogg, G J ^[1]; White, J W ^[2]; Herwig, K W; Sokol, P E ^[3]

---

1. Lyman Laboratory of Physics, Harvard University, Cambridge, MA (USA)
2. Research School of Chemistry, Australian National University, Canberra (Australia)
3. Department of Physics, The Pennsylvania State University, University Park, PA (USA)

The inelastic neutron scattering from H{sub 2} in C{sub 24}Cs(H{sub 2}){sub {ital x}} has been measured at momentum transfers of 8{lt}{ital Q}{lt}22 A{sup {minus}1} as a function of filling, 0.5{lt}{ital x}{lt}2.0, and temperature from 20 to 150 K. The observed scattering approaches the limiting behavior predicted by the Impulse Approximation (IA) for molecular hydrogen for {ital Q}'s greater than 15 A{sup {minus}1} and is insensitive to the filling factor and temperature up to {ital kT}/{ital M}{approx}0.1, where {ital M} is the enthalpy of hydrogen sorption. The results are analyzed using a model for the IA scattering from molecular hydrogen which takes into account the excitation of rotational transitions and the presence of a local orientational potential at the hydrogen adsorption sites. The average translational kinetic energy per molecule, which is determined by the effective local potential for the molecule, can be extracted from the measured scattering. For a powder sample, such as used in this measurement, determination of the kinetic energy requires independent knowledge of the orientational potential of the H{sub 2} molecules. Using the orientational potential inferred from previous tunneling measurements we extract an average translation kinetic energy of 320 K for the H{sub 2} molecule in the intercalate.

• Research Organization: Argonne National Laboratory (ANL), Argonne, IL
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 6057065
• Journal Information: Journal of Chemical Physics; (USA), Vol. 93:10; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
CLATHRATES
CRYSTAL STRUCTURE
HYDROGEN
ADSORPTION
CESIUM
GRAPHITE
INELASTIC SCATTERING
LOW TEMPERATURE
MOMENTUM TRANSFER
NEUTRON DIFFRACTION
ORIENTATION
VERY LOW TEMPERATURE
ALKALI METALS
CARBON
COHERENT SCATTERING
DIFFRACTION
ELEMENTAL MINERALS
ELEMENTS
METALS
MINERALS
NONMETALS
SCATTERING
SORPTION
656003* - Condensed Matter Physics- Interactions between Beams & Condensed Matter- (1987-)