Phonon dispersion curves in alpha-SiO2 and hcp He-3 and He-4 determined byinelastic X-ray scattering

The technique of inelastic X-ray spectroscopy with energy resolution in the meV regime matured with the high photon flux of the third generation synch rotrons of these days. The progress is demonstrated with the phonon dispers ion curves of single crystalline alpha-SiO2. The method also opened possibi lities to study the dynamics of systems not readily accessible by neutron s cattering, such as solid He-3. With inelastic X-ray spectroscopy, the phono n dispersion relation in single crystals of hcp He-3 could be observed for the first time. (C) 1999 Elsevier Science B.V. All rights reserved.