Abstract
The experimental measurement and the theoretical calculation of Raman scattering intensities present a number of challenges. We evaluate the currently available options with regard to our on-going studies of intensity in hydrocarbons and silanes. In the treatment of experimental data, anharmonic force fields permit the calculation of combination and overtone intensities as well as the resolution of anharmonic resonances. The structural dependence of the magnitude of the mean molecular polarizability derivative associated with the stretch of a single bond is confirmed at the B3LYP/aug-cc-pVTZ level of calculation. Although they do not exhibit nonlinear optical properties, derivatives for the straight chain alkanes show nonlinear trends in common with silanes, polyenes and polyaromatic hydrocarbons. The dynamic correction has been evaluated using time dependent DFT with the same basis set (TDDFT). The best calculations yield results that agree with the measured values to within experimental error.