Collisional relaxation of apocarotenals: identifying the S* state with vibrationally excited molecules in the ground electronic state S0*

The S* signal of carotenoids corresponds to vibrationally hot molecules in the ground electronic state S0*.

Picosecond Anti-Stokes Raman Excitation Profiles as a Method for Investigating Vibrationally Excited Transients

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.