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

Authors: Marggi Poullain, Sonia; Rubio-Lago, Luis; Chicharro, David V.; Boullagui, Aymen; Zanchet, Alexandre; Yazidi, Ounaies; Garcia-Vela, Alberto; Banares, Luis

Journal: MOLECULAR PHYSICS

Publication date: 2022/01/17

DOI: 10.1080/00268976.2021.1984598

Abstract: 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] .