Resonance Raman depolarization ratios as a probe of excited state dephasing times

The effect of the finite time for resonance Raman scattering on Raman depolarization ratios is evaluated. Partial depolarization of the resonance Raman emission will occur if the scatterers can rotate during the time interval between the absorption and emission steps. Equations are derived which express the depolarization ratio in terms of Fourier transforms of the usual time-dependent vibrational overlap multiplied by a rotational correlation function. Particularly simple results are obtained in the limit of severe inhomogeneous broadening of the electronic transition. The effect of the finite resonance scattering time on the line shape of the resonance Raman transition is also discussed.