title: High frequency dynamics in a monatomic glass.
abstract: The high frequency dynamics of glassy selenium has been studied by inelastic x-ray scattering at beam line BL35XU (SPring-8). The high quality of the data allows one to pinpoint the existence of a dispersing acoustic mode for wave vectors (Q) of 1.5<Q<12.5 nm(-1), helping to clarify a previ-ous contradiction between experimental and numerical results. The sound velocity shows a positive dispersion, exceeding the hydrodynamic value by approximately 10% at Q<3.5 nm(-1). The Q2 dependence of the sound attenuation Gamma(Q), reported for other glasses, is found to be the low-Q limit of a more general Gamma(Q) proportional, variant Omega(Q)(2) law, which applies also to the higher Q region, where Omega(Q) proportional, variant Q no longer holds.
authors.affiliation: Dipartimento di Fisica and INFM, Universitá di Roma "La Sapienza," I-00185, Roma, Italy.
authors.forename: T
authors.initials: T
authors.lastname: Scopigno
authors.forename: R
authors.initials: R
authors.lastname: Di Leonardo
authors.forename: G
authors.initials: G
authors.lastname: Ruocco
authors.forename: A Q R
authors.initials: AQ
authors.lastname: Baron
authors.forename: S
authors.initials: S
authors.lastname: Tsutsui
authors.forename: F
authors.initials: F
authors.lastname: Bossard
authors.forename: S N
authors.initials: SN
authors.lastname: Yannopoulos