Femtosecond time-resolved photoionization and photoelectron spectroscopy studies of ultrafast internal conversion in 1,3,5-hexatriene

Ultrafast photodynamics in a 1,3,5-hexatriene are studied using femtosecond time-resolved photoionization and photoelectron spectroscopy. The trans and cis isomers have distinctly different dynamics following excitation at the S2 origin near 250 nm. An intermediate, presumably the S1 state, is observed for both trans and cis isomers with lifetimes of 270 fs and 730 fs, respectively. Time-delayed photoelectron spectra of cis-hexatriene determine a 300 fs time scale for vibrational energy redistribution within the intermediate S1 state.