Density of states in solid deuterium: Inelastic neutron scattering study

The dynamics of solid deuterium (sD{sub 2}) is studied by means of inelastic scattering (coherent and incoherent) of thermal and cold neutrons at different temperatures and para-ortho ratios. In this paper, the results for the generalized density of states (GDOS) are presented and discussed. The mea...

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Bibliographic Details
Published in:Physical review. B, Condensed matter and materials physics Condensed matter and materials physics, 2009-08, Vol.80 (6), Article 064301
Main Authors: Frei, A., Gutsmiedl, E., Morkel, C., Müller, A. R., Paul, S., Urban, M., Schober, H., Rols, S., Unruh, T., Hölzel, M.
Format: Article
Language:English
Subjects:
COLD NEUTRONS
CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
DENSITY
DEUTERIUM
EXCITATION
FRM-II REACTOR
GADOLINIUM OXIDES
HCP LATTICES
HYDROGEN
INELASTIC SCATTERING
MOLECULES
NEUTRON DIFFRACTION
PHONONS
ROTATIONAL STATES
SOLIDS
THERMAL NEUTRONS
TIME-OF-FLIGHT METHOD
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Summary:The dynamics of solid deuterium (sD{sub 2}) is studied by means of inelastic scattering (coherent and incoherent) of thermal and cold neutrons at different temperatures and para-ortho ratios. In this paper, the results for the generalized density of states (GDOS) are presented and discussed. The measurements were performed at the thermal neutron time-of-flight (TOF) instrument IN4 at ILL Grenoble and at the cold neutron TOF instrument TOFTOF at FRM II Garching. The GDOS comprises besides the hcp phonon excitations of the sD{sub 2} the rotational transitions J=0{yields}1 and J=1{yields}2. The intensities of these rotational excitations depend strongly on the ortho-D{sub 2} molecule concentration c{sub o} in sD{sub 2}. Above E=10 meV there are still strong excitations, which very likely may originate from higher-energy damped optical phonons and multiphonon contributions. A method for separating the one-phonon and multiphonon contributions to the density of states will be presented and discussed.
ISSN:1098-0121
1550-235X
DOI:10.1103/PhysRevB.80.064301