The nu sub(3)- nu sub(4) difference band contribution to the CCl sub(4) symmetric stretch ( nu sub(1)) mode

The Raman spectrum of the symmetric stretching vibration ( nu sub(1)) of liquid carbon tetrachloride observed at 295K and reported repeatedly over the last 80years clearly shows four of the five more abundant isotopomers at 440-470cm super(-1). At the lower energy end of this spectrum, additional intensity due to isotopomeric contributions from the symmetric stretch for v=1 arrow right 2 (hotbands) partially overlaps the prominent v=0 arrow right 1 features, and accounts for about 18% of the integrated intensity at 295 K in agreement with theory. When these two patterns are modeled and subtracted from the experimental spectrum, a feature underlying almost exactly the C super(35)Cl sub(4) (v=0 arrow right 1) band at 462.5cm super(-1) becomes apparent. We propose that this feature is the nu sub(3)- nu sub(4) difference band. Observations at lower temperatures, and of the combination bands, and the polarized Raman spectra are consistent with this hypothesis. Copyright copyright 2014 John Wiley & Sons, Ltd. Careful analysis reveals the nu sub(3)- nu sub(4) difference band Raman intensity contribution underlying the nu 1 mode of the C super(35)Cl sub(4) isotopomer and isolates the nu sub(1) hot band contributions in the low frequency portion of the symmetric stretch peak. Uncovering the intensity contribution due to nu sub(3)- nu sub(4) resolves a long-standing discrepancy between theoretical prediction and empirically observed intensities of the C super(35)Cl sub(4) symmetric stretch spectral signature.