The Raman spectrum of gypsum

The general problems involved in the Raman study of monoclinic crystals are examined, and a simple procedure is described for the analysis of the vibrational spectrum of such crystals which permits the modes predicted by group theory to be unambiguously assigned. Gypsum is used as an illustrative example of this method, and a complete analysis of its vibrational Baman spectrum is presented. The importance of examining all the components of the polarizability tensor is demonstrated. A discussion is given of the observed crystal field effects in gypsum. Results on the Raman spectrum due to vibrational modes of the water molecules in the 3000–3800 cm−1 region are presented and are compared with observations of Stekhanov of bands in this region.