Abstract

Resonant impulsive excitation creates vibrational coherence on the ground electronic surface, through the Resonant Impulsive Stimulated Raman Scattering process (RISRS)¹. The ensuing vibrational motion has been detected in various schemes as periodical modulations in transient scattering or transmission of the delayed probe pulse². An example for this process was observed by us in the photodissociation experiments of the ${\text{I}}_3^{-}$ ion in different polar solvents³. The results for two solvents, water and ethanol, are presented in figure 1. Periodic modulations in the transient transmission of the 308 nm probe pulse are seen, the strong solvent dependence of the decay of the modulations is evident. The modulations are assigned to coherence in the ground state symmetric stretch vibration of triiodide. A general framework for interpreting these results is required. We chose to model the phenomena within a quantum mechanical model which takes into consideration strong field effects, solvent induced dissipation and thermal population.

© 1994 Optical Society of America