High—pressure Raman study of liquid and crystalline CS2 up to 45 kbar at 300 K

The Raman spectra of liquid and crystalline CS2 have been measured at pressures up to 45 kbar and 300 K. The pressure dependences of the internal modes and the four librational lattice modes are reported: For the internal modes, the frequency of the symmetrical stretching modes v1 increases hardly with pressure, because of the very strong S=C=S bonding. The overtones 2v2 of the bending modes in the liquid state shifted to lower frequencies a little with increasing pressure, and splitted by 18 cm-1 into two major peaks at the solidification point (about 13 kbar). In the pressure-induced solid phase above 13 kbar at 300 K, the four external (librational) modes were observed, which have been predicted by the symmetry consideration. Comparison of the spectrum of high-pressure crystals at 300 K with that of the low-temperature crystals at 1 bar indicates that the structure of each crystal resembles mutually.