Two-phonon vibrational spectra ofAs2S3. I. Crystalline phase

Abstract

Polarized two-phonon Raman and infrared spectra of crystalline ${\mathrm{As}}_2$ ${\mathrm{S}}_3$ have been measured at 300 and 80 K. Evidence of vibrational decoupling of the normal modes of the crystalline layer into inter- and intrachain vibrations is presented. The observed narrowness of many of the two-phonon spectral features of the crystalline form is attributed to the layered nature of the crystal structure and to the vibrational decoupling of the layer modes.