Inelastic X-ray Scattering measurements of the dynamics structure factor have bene performed on vitreous Beryllium Fluoride ({\it v-}BeF2) at T=297 K in the momentum transfer, Q, range Q=1.5÷10 nm−1. We find evidence of well defined high frequency acoustic modes. The energy position and linewidth of the excitations disperse with Q as ∝Q and ∝Q2, respectively up to about one half of the first maximum of the static structure factor. Their magnitude compare favorably with low-frequency sound velocity and absorption data. The results indicate worth mentioning similarities of the high frequency collective dynamics of different network forming glasses such as {\it v-}B2O3 and {\it v-}SiO2.
@article{arxiv.cond-mat/0207030,
title = {High frequency acoustic modes in vitreous Beryllium Fluoride probed by inelastic X-ray scattering},
author = {T. Scopigno and S. N. Yannopoulos and D. Th. Kastrissios and G. Monaco and E. Pontecorvo and G. Ruocco and F. Sette},
journal= {arXiv preprint arXiv:cond-mat/0207030},
year = {2009}
}