Multiple Product Channels in the Collision Free UV Photodissociation of 2-Nitropropane

摘要

In the experiments reported herein, we present our initial results concerning the different photodissociation pathways which accompany the UV photolysis (222, 249, and 308 nm) of 2-nitropropane (2NP), under collision-free conditions. Since there are no nitrogen atom lone pair electrons, excitation involves the promotion of an oxygen atom lone pair electron into an antibonding pi-group orbital. Even though the subsequent radiationless transition out of S sub 1 is rapid, the nuclear motions which commence upon absorption of a photon cause the nuclei to reconfigure, particularly in the vicinity of the NO2 group. The radical-like nature of the oxygen can facilitate the formation of a 5-membered ring, which can lead to products such as OH and HONO, and NO2 can also be liberated efficiently before the nuclear energies dissipate into the vibrational reservoir of the propyl radical. We find that all three of these products are produced at each of the photolysis wavelengths, and that OH is a nascent product in all instances.