2004/02/05 by Barbara Ruzicka, B. Ruzicka, T. Scopigno +11 · 1 citation
Earth and Planetary Sciences · Materials Science · Physics and Astronomy · #Glass properties and applications #Material Dynamics and Properties #Seismic Waves and Analysis #cond-mat.dis-nn
paper · pdf · doi:10.1103/physrevb.69.100201
5 pages, 3 figures. To appear in Phys. Rev. B
arxiv created 2004/02/05 · openalex publication_date 2004/03/12 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The dynamic structure factor S(Q,\ensuremathω), of vitreous silica, has been measured by inelastic x-ray scattering in the exchanged wave-vector (Q) region Q=4--16.5nm^\ensuremath-1 and up to energies \ensuremath\Elzxh\ensuremathω=115meV in the Stokes side. The unprecedented statistical accuracy in such an extended energy range allows us to accurately determine the longitudinal current spectra and the energies of the vibrational excitations. The simultaneous observation of two excitations in the acoustic region and the persistence of propagating sound waves up to Q values comparable with the (pseudo-)Brillouin-zone edge allow us to observe a positive dispersion in the generalized sound velocity that, around Q\ensuremath≈5nm^\ensuremath-1, varies from \ensuremath≈6500 to \ensuremath≈9000m/s; this phenomenon was never experimentally observed in a glass.