The effect of phonon scattering upon resonance Raman scattering: The use of monochromatically excited resonant light scattering as a probe of ultrafast dephasing and relaxation in the condensed phase

The effects of excited state relaxation and dephasing upon resonance Raman scattering from a molecule in the condensed phase are considered from the perspective of a simple scattering event model, in the weak field limit. The model contains the minimum interactions necessary to produce dephasing of monochromatically excited resonant light scattering (MERLS). Emphasis is placed on how the different relaxation and dephasing processes determine the coherence properties of MERLS, from localized electronic states of a molecule perturbed by the environment. We consider how MERLS can be used to probe the line broadening mechanisms of vibronic absorption bands and associated phonon side bands. A comparison is made between the dephasing effects observed by the time dependent coherent spectroscopic techniques (e.g., photon echoes) and those detectable by spectral analysis of MERLS.