A method for estimating vibrational quantum numbers of vibrationally excited
transients in solution is proposed. In this method, we calculate anti-Stokes Raman
excitation profiles (REPs) which are characteristic of the initial vibrational states
involved in the Raman process, and compare them with observed anti-Stokes intensities.
We have applied this method to vibrationally hot molecules of canthaxanthin in the So
state and those of trans-stilbene in the S1 state. For canthaxanthin, it has been found that
the vibrationally excited transients are for the most part on the ν=1 level of the C═C
stretching mode, and that excess vibrational energy is statistically distributed among all
intramolecular vibrational modes. As for S1 stilbene, vibrational transients are shown to
be mostly on the ν=1 level for two vibrational modes examined, while the excess
vibrational energy is probably localised on the olefinic C═C stretching mode.