Concentration effects on absolute depolarized Rayleigh ratios and effective polarizability derivatives of CS2in liquid mixtures with CCl4

Abstract

Experimental results are reported from polarized and depolarized Raman intensity measurements in combination with absolute depolarized Rayleigh ratios of liquid CS2 in CCl4 mixtures at 25°C. Using a calibrated Raman spectrometer it was possible to determine the concentration dependence of g 2 · γ2 eff of CS2. Intensity measurements of the polarized and depolarized Raman spectra of the symmetric stretching vibration of CS2 under the same conditions allowed the determination of the effective values of α01 and γ01 respectively to the normal mode Σ+ g in the liquid phase. In the neat liquid, α01 = 0·19 Å3 and γ01 = 0·22 Å3. In mixtures with CCl4 the values of α01 decrease at lower CS2 concentration whereas the values of γ01 increase. These results indicate that the isotropic induced dipole field is increasingly cancelled as the environment becomes more isotropic while the anisotropic part is amplified in CCl4. A report is also given of an anomalous concentration behaviour of the intensity of the combination mode v 1 + v 2-v 2 on the low frequency side of the v 1 transition which is amplified relative to the intensity of the v 1 mode as the CCl4 concentration increases.