Investigation of the fast relaxation in glass-forming selenium by low-frequency Raman spectroscopy

The low-frequency Raman spectra of liquid and vitreous selenium are investigated. It is demonstrated that the temperature dependence of the intensity of the fast relaxation at the glass transition temperature (Tg = 308 K) exhibits a specific feature. This feature manifests itself in a sharper increase in the intensity at temperatures T > Tg as compared to that observed at lower temperatures. The intensities of the fast relaxation at the critical temperature Tc are evaluated by the extrapolation of the linear dependence to the temperature range T > Tg in the framework of the mode-coupling theory. The new results obtained for selenium are compared with the available data for other glass-forming materials (boron oxide, toluene, arsenic sulfide). It is shown that, for all the glasses under investigation, the parameter describing the contribution of the fast relaxation to the Raman spectrum takes on the same value at the critical temperature Tc and is approximately equal to 0.3.