Raman and infrared spectra of vitreousAs2O3

We report the polarized reduced Raman spectra, the infrared reflectivity, and dielectric constants of bulk ${\mathrm{As}}_2$ ${\mathrm{O}}_3$ glass for vibrational frequencies up to 1500 ${\mathrm{cm}}^{-1\mathrm{}}$. Longitudinal and transverse optical modes are identified in the high-frequency region, as are some features of the second-order response. The atomic motions associated with several lines are inferred from an analogy with the spectra of the tetrahedral glass Ge${\mathrm{O}}_2$. Our assignments bring into question the force constants previously deduced by Papatheodorou and Solin. The spectra of bulk ${\mathrm{As}}_2$ ${\mathrm{S}}_3$ glass and ${\mathrm{As}}_2$ ${\mathrm{Se}}_3$ glass are also given a parallel interpretation.