FT-IR and Raman microscopic study at 293 K and 77 K celestine, SrSO4, from the middle triassic limestone (Muschelkalk) in Winterswijk, The Netherlands

This paper describes the Raman and infrared spectroscopy of SrSO or celestine from the Muschelkalk of Winterswijk, The Netherlands. The infrared absorption spectrum is characterised by the SO modes v at 991 cm, v at 1201, 1138 and 1091 cm, and v at 643 and 611 cm. An unidentified band is observed at 1248 cm. In the Raman spectrum at 293 K the v mode is found at 1000 cm and is split in two bands at 1001 and 1003 cm upon cooling to 77 K. The v mode, not observed in the infrared spectrum, is observed as a doublet at 460 and 453 cm. The v mode is represented by four bands in the Raman spectrum at 1187, 1158, 1110 and 1093 cm and the v mode as three bands at 656, 638 and 620 cm. Cooling to 77 K results in a general decrease in bandwidth and a minor shift in frequencies. A decrease in intensities is observed upon cooling to 77 K due to movement of the Sr atom towards one or more of the oxygen atoms in the sulfate group