DENSITY AND TEMPERATURE STUDY OF THE NONCOINCIDENCE EFFECT IN LIQUID CARBON-DISULFIDE

The noncoincidence of the anisotropic and isotropic peak frequencies i n the allowed Raman nu(1) vibrational mode of liquid CS2 is studied ov er an extended density range (1.18 to 1.58 g/cm(3)) by varying pressur e (0.001 to 5.0 kbar) and temperature (-55 to 80 degrees C). The nonco incidence value is negative and the absolute value increases as a func tion of both increasing density, at constant temperature, and increasi ng temperature, at constant density. The noncoincidence of the anisotr opic and isotropic peak frequencies is attributed to a quadrupole indu ced transition dipole coupling mechanism because changes in the noncoi ncidence value can be correlated with changes in the intensity of the forbidden nu(1) infrared mode.