Effect of pressure and temperature on the Raman spectra of solid CO2

High pressure Raman studies up to 18 GPa have been made on solid CO2 at room temperature and low temperatures. Changes in the spectral features of external modes are used to draw conclusions on the structural behavior under compression. Anharmonic contributions to the intermolecular potential and their pressure dependence are determined from the pressure and temperature shift of librational frequencies. Anharmonic contributions to the intramolecular potential are determined by pressure tuning of the Fermi resonance.