CORRELATION-EFFECTS ON RAMAN-SCATTERING FROM LOW-ENERGY VIBRATIONAL-MODES IN GLASSES .2. EXPERIMENTAL RESULTS

New experimental results of low-frequency Raman scattering from differ ent glasses are presented. They are compared to the vibration density of states obtained from inelastic neutron scattering to deduce the lig ht-vibration coupling coefficient C(omega) as a function of the vibrat ion frequency. It was found that C(omega) is-proportional-to omega2 at very low frequency omega < 20 cm-1 in inorganic glasses (SiO2,B2O3) a nd that C(omega) is-proportional-to omega at low frequency in polymer glasses and in inorganic glasses for omega > 20 cm-1. Our experimental results for glasses are interpreted by assuming no correlation at ver y low-frequency and only radial correlation at low-frequency. A full c orrelation would exist in silica-aerogels in which the effect of rando m fluctuations would be negligible.