Theory of dispersion of raman scattering by molecules containing two identical chromophores

It is shown that the interaction between identical chromophores of freely orienting rigid bichromophoric molecule described by the non‐diagonal elements of the molecular damping matrix may lead to unusual dispersion of the depolarization ratios of Raman bands. The forms of the predicted dispersion curves depend on the mechanism for the occurrence of a Raman band and on the mutual orientation of the chromophores. The dispersion curves have anomalous extrema at the frequency of the pure electronic transition of the molecule, i.e. at the maxima of the excitation profiles of Raman lines in an examined frequency field, in contrast to known dispersion curves of the depolarization ratio, the extrema of which are often found to coincide with minima rather than maxima in the excitation profile. This circumstance favours the experimental observation of the predicted curves. Also presented is an excitation profile of the vibrational Raman optical activity signal for such randomly oriented molecules with optically inactive chromophores. This profile has one sign only, unlike the double‐signed spectrum of circular dichroism for such molecules. This makes the recording of this profile under conditions of inhomogeneous broadening of spectral lines more convenient than recording the circular dichroism spectrum.