Raman intensities of ethane and deuterated derivatives

Experimental gas phase Raman scattering differential cross sections and depolarization ratios of ethane and its deuterated derivatives are reported. A consistent interpretation of these data is accomplished in the frame of the bond polarizability model. The bond polarizability derivatives ∂αCH/∂rCH here obtained are, within the estimated uncertainties, the same as for other hydrocarbon molecules not only for the mean polarizability but for the anisotropy as well. On the other hand, the C–C bond properties are proved to be essentially the same in ethane and in diamond. In ethane isotopic species with synclinal and antiperiplanar conformers the experimental intensities are not always in the ratio 2:1. A satisfactory explanation of this apparent anomaly is achieved on the basis of the calculated Raman tensors of homologous normal modes which are quite different in some cases.