BRILLOUIN AND RAMAN CROSS-SECTIONS IN SILICATE-GLASSES

Light-scattering measurements of Raman and Brillouin spectra of silica te glasses are presented. Spectra collected in a wide frequency range allow us to measure the low-frequency Brillouin doublet and the freque ncy-extended Raman spectrum. As a result we are able to determine the elasto-optic constants as well as the Raman efficiency in polarized an d depolarized scattering configurations. Particular attention is devot ed to the integrated intensity of Raman scattering in the medium frequ ency range (0-100 cm(-1)) where spectra are ascribed to intramolecular modes of the glassy structure.