Subpicosecond solvent dynamics in charge-transfer transitions: Opportunities in Resonance Raman spectroscopy

Resonance Raman spectroscopy is an established tool for the determination o f structure and dynamics in electronically excited states. In condensed-pha se systems, Raman excitation profiles and electronic absorption spectra dep end on changes in molecular geometry and solvation structure induced by ele ctronic excitation. Recent studies of solvent isotope effects on resonance Raman intensities in charge-transfer excitations reveal solvent dynamics ta king place on a subpicosecond time scale and vibrational mode-specific solu te-solvent interactions. These discoveries present challenges to the curren t working theories for analysis of resonance Raman and absorption spectra.