The far-infrared spectra of arsenic chalcogenides

Abstract

The far-infrared spectra of AsS, As₂S₃, As₄Se₃, and As₂Se₃ are reported for the range 15-400 cm^-1. For As₄S₃ molecules, of symmetry C_3v, strong bands at 370 cm^-1 and 340 cm^-1 arise from symmetric As-S stretching frequencies of symmetry class A₁ and a strong band at 176 cm^-1 arises from a S-4s-S bending mode of degenerate class E. For As₂Se₃, bands in the region 90-130 cm^-1 are identified as Se-As-Se bending modes and bands between 200 and 280 cm^-1 are due to As-Se stretching modes.