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Free keywords:
phonon widths; pressure dependence; stable isotopes; anharmonicity; tetrahedral semiconductors
Abstract:
In the course of a few years before his untimely death, Jean Michel
Besson and his group performed the most comprehensive and detailed
studies of the phonon dispersion relations of semiconductors on
pressure using inelastic neutron scattering (INS). Because of the
intrinsically poor resolution of this technique, parallel studies of
phonon line widths are well-nigh impossible. Such studies would be of
considerable interest for revealing ubiquitous anomalies in the phonon
self-energies, but so far they have been confined to k-points near the
center of the Brillouin zone, as required by laser Raman spectroscopy.
Some interesting results obtained in this manner are presented. The
possibility of simulating the effects of high pressure by changing the
isotopic composition of the material will also be touched upon. It is
hoped that recent developments and activity concerning the technique of
Neutron Spin Echo spectroscopy will open new possibilities for using
Besson's cells for the determination of the pressure dependence of
phonon line widths.
