Depolarization Dispersion of Totally Symmetric Fundamentals in Resonance Raman Spectra. Analysis for Azobenzene Dyes

The resonance Raman excitation profiles and depolarization dispersions for totally symmetric vibrations are studied under the energy region corresponding to an excitation of two low-energy states of 4-nitro-4'-diethylaminoazobenzene dye. Ιn a contrast to the earlier analysis of this dye we assume that the low-energy states of the molecule studied have different polarizations. It results in the depolarization dispersions of the Raman lines of totally symmetric vibrations. The effect is illustrated for two vibrations: V4 = 1342 cm-1 and ν7 = 1448 cm -1 for which excitation profiles show . distinctive intensity distribution patterns due to interferences between the vibrational manifołds of the overlapping states. The nature of the electronic (resonant) states and the magnitudes of Franck-Condon parameters determined from the experiment are also briefly discussed. PACS numbers: 33.20.Fb