Eugene J. Bernard, Brian R. Strazisar, and H. Floyd Davis*

The photodissociation of H₂CN radicals at 279-285 nm was studied using high-n Rydberg H-atom photofragment translational energy spectroscopy. A slight preference for H atom scattering perpendicular to the laser polarization axis (b = -0.10 ± 0.03) indicates that the near-UV transition corresponds to a "forbidden" 2B1 ¬ 2B2 electronic transition made weakly allowed for excitation to A2 vibronic levels. Of the total excess energy (» 77 kcal/mole), on average approximately 65% appears as HCN internal excitation. Dissociation proceeds via an indirect mechanism likely involving the ground electronic state.