VIBRATIONAL PREDISSOCIATION IN S1 1-METHYLINDOLE VANDERWAALS CLUSTERS

The excited state dynamics of the 1-methylindole(Ar)1, 1-methyl(d3)ind ole(Ar)1, 1-methylindole(CH4)1, and 1-methyl(d3)indole(CH4)1 van der W aals clusters have been investigated in a free jet expansion. Time and energy resolved emission spectroscopic techniques were used to determ ine intramolecular vibrational redistribution rates and vibrational pr edissociation rates. All of the clusters were found to predissociate w hen excited with sufficient vibrational energy in the S1 state. The pr edissociation dynamics were found to be consistent with a serial model in which energy transfer from the 1-methylindole skeletal modes to th e van der Waals modes precedes the dissociation step. These results ar e compared with earlier results on indole clusters. The density of vib rational states in the van der Waals clusters was found to be the most important factor in determining the vibrational dynamics. The role of the chromophore skeletal vibrations is also discussed.