The Raman spectrum of Cs2SeO4 crystals

Abstract

The Raman spectrum of Cs2SeO4 crystals has been obtained at T = 20 K. We have observed 23 of the 24 external modes predicted by a model with four formula units per unit cell. A comparison of the internal mode frequencies with those of the solution spectrum shows that the charge on the SeO4 tetrahedron is, in the crystal phase, less than two electrons. We have obtained the temperature dependence of the Raman spectrum from 20 to 650 K. For the internal modes only, we have observed the pressure dependence up to 25 kbars, and we have evaluated the volume dilatation and the interaction contributions to their total temperature dependence. (1 bar = 100 kPa.)