Benzyl Radical Photodissociation Dynamics at 248 nm.

The photodissociation of jet cooled benzyl radicals, C7H7, at 248 nm has been studied using photofragment translational spectroscopy. Two dissociation channels were observed, H + C7H6 and CH3 + C6H4. The translational energy distribution determined for each channel suggests that both dissociation mechanisms occur via internal conversion to the ground state followed by intramolecular vibrational redistribution and dissociation. The branching ratio between these two channels has been measured to be (CH3 + C6H4)/(H + C7H6) = 0.011 ± 0.004. The dominance of the H + C7H6 channel is corroborated by the branching ratio calculated using Rice-Ramsperger-Kassel-Marcus theory.