Far infrared study of carbon disulfide at high pressures

Far-infrared spectra of carbon disulfide in diamond anvil cells at ambient temperature and at pressures up to 8 GPa are reported. The freezing pressure is confirmed to be 1.3 GPa, and no solid state phase transitions are observed. Above 8 GPa irreversible darkening of the sample occurs, the result of partial decomposition. Three components of the bending mode are detected, and their peak wavenumbers all decrease slightly with pressure, indicative of a weakening of intramolecular bonding. The wavenumber of the single translational peak shows a substantial increase over the pressure range investigated, corresponding to a strengthening of intermolecular bonding by a factor of about 2.5.