Comparison of Raman- and neutron-scattering data for glass-forming systems

Low-frequency Raman- and neutron-scattering spectra are compared for the three glass formers polybutadiene, polystyrene, and ${\mathrm{SiO}}_2$ at different temperatures. One finds similar neutron and Raman spectra in the frequency range where the quasielastic (relaxational) contribution dominates, but a marked quasilinear increase of the light-scattering sensitivity above the vibrational boson peak. Analysis of the data shows that there is some intrinsic relation between the quasielastic contribution and the boson peak vibrations. These results are compared with predictions of different models.