Imaging the elusive C-C bond dissociation channel of photoexcited ethyl radical

The C-C bond dissociation channel of the ethyl (CH3-CH2) radical is investigated at 197.4, 199.98 and 201 nm by velocity map imaging and resonance enhanced multiphoton ionisation (REMPI) detection of the produced CH3 fragments. On the light of high-level ab initio calculations performed in this work, up to four dissociation pathways are identified leading, respectively, to ground state CH3 radicals in correlation with CH2 fragments in the first four electronic states. The major pathway is associated with threshold dissociation over an exit barrier located at the point of a conical intersection between the initially populated 3p(A), state and a dissociative valence state. As discussed in the text, the concomitance of both features opens the narrow window in which C-C bond dissociation occurs for ethyl and, presumably, for other similar alkyl radicals. [GRAPHICS] .

Automated summary

The C-C bond dissociation channel of the ethyl radical was investigated through velocity map imaging and REMPI detection of CH3 fragments produced at 197.4, 199.98, and 201 nm. Up to four dissociation pathways were identified, with the major pathway involving an exit barrier at the conical intersection between the 3p(A) state and a dissociative valence state.