Photofragment imaging study of the CH{sub 2}CCH{sub 2}OH radical intermediate of the OH+allene reaction
- James Franck Institute and Department of Chemistry, University of Chicago, Chicago, Illinois 60637 (United States)
These velocity map imaging experiments characterize the photolytic generation of one of the two radical intermediates formed when OH reacts via an addition mechanism with allene. The CH{sub 2}CCH{sub 2}OH radical intermediate is generated photolytically from the photodissociation of 2-chloro-2-propen-1-ol at 193 nm. Detecting the Cl atoms using [2+1] resonance-enhanced multiphoton ionization evidences an isotropic angular distribution for the Cl+CH{sub 2}CCH{sub 2}OH photofragments, a spin-orbit branching ratio for Cl({sup 2}P{sub 1/2}):Cl({sup 2}P{sub 3/2}) of 0.28, and a bimodal recoil kinetic energy distribution. Conservation of momentum and energy allows us to determine from this data the internal energy distribution of the nascent CH{sub 2}CCH{sub 2}OH radical cofragment. To assess the possible subsequent decomposition pathways of this highly vibrationally excited radical intermediate, we include electronic structure calculations at the G3//B3LYP level of theory. They predict the isomerization and dissociation transition states en route from the initial CH{sub 2}CCH{sub 2}OH radical intermediate to the three most important product channels for the OH+allene reaction expected from this radical intermediate: formaldehyde+C{sub 2}H{sub 3}, H+acrolein, and ethene+CHO. We also calculate the intermediates and transition states en route from the other radical adduct, formed by addition of the OH to the center carbon of allene, to the ketene+CH{sub 3} product channel. We compare our results to a previous theoretical study of the O+allyl reaction conducted at the CBS-QB3 level of theory, as the two reactions include several common intermediates.
- OSTI ID:
- 21024336
- Journal Information:
- Journal of Chemical Physics, Vol. 127, Issue 15; Other Information: DOI: 10.1063/1.2776268; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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