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

8 pags., 4 figs., 2 tabs.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 3pA 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.D. V. C. acknowledges financial support from Spanish MINECO under the FPI predoctoral program. A. G.-V., O. Y., and A. B. acknowledge funding from the I-COOP program from Consejo Superior de Investigaciones Científicas (CSIC) [I-COOP COOPB20364], which made possible a research stay of A.B. at Instituto de Física Fundamental, CSIC. This work has been financed by the Spanish Ministry of Science and Innovation [PGC2018-096444-B-I00].Peer reviewe