The influence of angular dependent intermolecular forces on vibrational spectra of solution phase molecules

Abstract

The zeroth, first, and second moments of the solution phase infrared, isotropic Raman, and anisotropic Raman bands of a totally symmetric mode are calculated. The existence of a strong orientationally dependent intermolecular potential is shown to lead to concentration dependent peak frequencies and bandwidths, as well as possible deviations from Beer’s law. Assumining a dominant transition dipole–transition dipole interaction, expressions for the explicit concentration dependence of the infrared, isotropic Raman, and anisotropic Raman first moments are derived and applied to the interpretation of the observed Raman spectra of polar molecules in the solution phase.