Experimental and Theoretical Investigation of the Electronic Spectroscopy of H$_{2}$CN

The electronic spectrum of H$_{2}$CN, recorded through cavity ring-down spectroscopy, is reported. The radical was prepared by 193 nm photolysis of monomeric formaldoxime vapor. Two diffuse features are observed in the 34800-35800 cm$^{-1}$ spectral range, along with the $A - X$ (1,0) band of the OH co-fragment. These are assigned as vibronic transitions to the ground and 2$b_{1}$ (umbrella mode) levels of the second excited, $^{2}A_{1}$ state from the ground $^{2}B_{2}$ state. Experimental and simulated rotational profiles of these bands agree extremely well with each other for an assumed type-B electric-dipole allowed $^{2}A_{1} \quad \leftarrow \quad ^{2}B_{2}$ transition appropriate to this transition. A theoretical investigation of the dissociation pathways for electronically excited H$_{2}$CN is also presented. The upper states of the observed bands cannot dissociated directly, but higher $b_{1}$ levels are above the excited-state dissociation limit.