Raman and infrared study of 100 MeV swift Ag8+ heavy ion irradiation effects in CaSO4.2H2O single crystals

The modifications of calcium sulphate (CaSO4.2H2O) single crystals are investigated by means of Raman and Fourier transform infrared spectroscopy (FT-IR) using 100 MeV Ag8+ ions in the fluence range 1 x 1011 to 5 x 1013 ions/cm2. It is observed that the intensities of the Raman modes decrease with increase in ion fluence. We determined damage cross-section (σ) for all the Raman active modes and found to be different for different Raman modes. Further, FT-IR studies have been carried out to confirm surface amorphisation for a fluence of 1 x 1013 ions/cm2. It is observed that the absorption peaks at 1132-1156 cm-1 corresponds to ν3(SO42-) mode. The decrease in Raman peaks intensity with ion fluence is attributed to degradation of ν3(SO42-) modes present on the surface of the sample.