Excited state dynamics of H2CN radicals

The photodissociation of H2CN radicals at 274-288 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 (beta = -0.10 +/- 0.03) indicates that the near-UV transition corresponds to a "forbidden" B-2(1) <-- B-2(2) electronic transition made weakly allowed for excitation to A(2) vibronic levels. Of the total excess energy (approximate to 77 kcal/mol), on average approximately 65% appears as HCN internal excitation. Dissociation proceeds via an indirect mechanism likely involving the ground electronic state. (C) 1999 Elsevier Science B.V. All rights reserved.