Energy content of methyl radicals produced in the UV photodissociation of azomethane

A pulsed UV laser has been used to photolyze azomethane and effect state-selective ionization of neutral methyl photofragments. The resultant methyl ions, detected using time-of-flight mass spectrometry, have translational energies consistent with one of the two energetically distinct methyl photofragments observed in a study carried out by North et al. A recently developed barrier impulsive model provides a good qualitative prediction of the observed methyl photofragment kinetic energy. In addition, the partitioning of energy within the methyl photofragment observed in this study is consistent with its having originated from the second step in the overall dissociation process (CH3N2 → CH3′ + N2).