Extended Near-Infrared Resonance Raman Investigations of an Organic Mixed-Valence System: Diazatetracyclodiene Radical Cation

Resonance Raman scattering studies in the extended near-infrared region show that six modes are coupled to the intramolecular charge-transfer transition in the mixed-valence radical cation diazatetracyclodiene. Spectral analysis based on time-dependent scattering theories shows that all six modes make substantial contributions to the vibrational reorganization energy. Measured Raman scattering cross sections were found to be considerably less than would be predicted by the conventional time-dependent scattering theories utilized here, evidently owing to complications arising from avoided surface crossings and anharmonic wave packet propagation. An examination of the classical and nonclassical kinetic effects of the coupled modes indicated that a considerable influence on the rate of intramolecular electron transfer is exerted by the modes collectively.