Correlation effects on Raman scattering from low-energy vibrational modes in glasses. II. Experimental results

Abstract

New experimental results of low‐frequency Raman scattering from different glasses are presented. They are compared to the vibration density of states obtained from inelastic neutron scattering to deduce the light‐vibration coupling coefficient C(ω) as a function of the vibration frequency. It was found that C(ω)∝ω2 at very low frequency ω<20 cm−1 in inorganic glasses (SiO2,B2O3) and that C(ω)∝ω at low frequency in polymerglasses and in inorganic glasses for ω≳20 cm−1. Our experimental results for glasses are interpreted by assuming no correlation at very low‐frequency and only radial correlation at low‐frequency. A full correlation would exist in silica‐aerogels in which the effect of random fluctuations would be negligible.