The frequency-dependent depolarization ratio of the low-frequency Raman scattering of two inorganic systems in their glassy, supercooled, and molten states

A temperature-dependent, low-frequency Raman study for a strong and a fragile glass-forming liquid is reported in order to elucidate the frequency and temperature sensitivity of the depolarization ratio spectrum, ρ(ω,T). Changes observed in ρ(ω,T) are directly reflected on the spectral features of the Raman coupling coefficient, Cαβ(ω). Our data provide evidence for polarization dependence of this coefficient, which has been completely overlooked in studies concerning the experimental determination of Cαβ(ω) through a comparison of neutron and reduced Raman spectra. The current status considering the frequency dependence of the coupling coefficient is briefly reviewed from the theoretical, experimental, and computer simulation points of view. The experimental data suggest that a reconsideration of the approaches employed should be undertaken.