LOW-FREQUENCY RAMAN-SCATTERING OF AS2SXSE3-X

Low-frequency ( less than 60 cm** minus **1) Raman spectra have been measured for a series of chalcogenide glasses and crystals of the form As//2S//xSe//3// minus //x. Comparison of the spectra for x equals 0 and x equals 0. 5 of the crystals clearly establishes the rigid layer (RL) mode character of the peaks near 21 and 31 cm** minus **1 and the admixture of RL and intralayer modes for the series of peaks near 50 cm** minus **1. The observed lineshape of the glasses is interpreted in terms of a density of states of optic modes.