Far infrared transmission and Raman scattering in Pb-As-S semiconducting glasses

Various compositions (x = 0.1?0.625) in the pseudo-binary (As₂S₃)_1?x(PbS)_x have been prepared in the glassy form. Thermal analysis of the prepared glasses shows a multiphase non-crystalline structure. Their far-infrared transmission (50–450 cm^-1) and first order Raman scattering have been observed for the first time and the observations indicate a two mode behaviour of the glasses. The frequencies and symmetries of AsS₃ bond-stretching modes are maintained in this alloy system and are therefore determined by the local order, and not the dimensionality or longer range order of the network.