Vibration spectra of the isomorphous proustite-pyrargyrite series

The results are given of a study of the vibrational (Raman scattering and infrared absorption) spectra of a proustite (Ag₃AsS₃) single crystal and of a series of polycrystalline isomorphously substituted (As → Sb) proustite-pyrargyrite solid solutions. The optical properties and the unit cell parameters are given. The method of synthesis is described. The force constants of the radical AsS₃^3– are calculated, and a factor-group analysis of the proustite crystal is made. The normal vibrations are interpreted on the basis of a comparison of the spectra of frequencies established for the radical, the spectra of the isomorphously substituted series, and the polarization spectra of the proustite single crystal.