The high frequency dynamics of glassy Selenium has been studied by Inelastic X-ray Scattering at beamline BL35XU (SPring-8). The high quality of the data allows one to pinpoint the existence of a dispersing acoustic mode for wavevectors (Q) of 1.5<Q<12.5 nm−1, helping to clarify a previous contradiction between experimental and numerical results. The sound velocity shows a positive dispersion, exceeding the hydrodynamic value by ≈ 10% at Q<3.5 nm−1. The Q2 dependence of the sound attenuation Γ(Q), reported for other glasses, is found to be the low-Q limit of a more general Γ(Q)∝Ω(Q)2 law which applies also to the higher Q region, where Ω(Q)∝Q no longer holds.
@article{arxiv.cond-mat/0312033,
title = {High frequency dynamics in a monatomic glass},
author = {T. Scopigno and R. Di Leonardo and G. Ruocco and A. Q. R. Baron and S. Tsutsui and F. Bossard and S. N. Yannopoulos},
journal= {arXiv preprint arXiv:cond-mat/0312033},
year = {2009}
}