Reactive and Inelastic Channels in the Ca···FCH3 Transition State: A Simple Branching Mechanism

To study the excited state dynamics between a calcium atom and the CH3F molecule, a Ca···CH3F 1:1 complex has been prepared by a supersonic expansion with laser ablation of calcium metal in the gas phase. Tunable laser excitation of these complexes in molecular states correlating to Ca 1P1(4s4p) + C...

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Veröffentlicht in:The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Molecules, spectroscopy, kinetics, environment, & general theory, 2015-06, Vol.119 (23), p.6099-6110
Hauptverfasser: Briant, M, Gloaguen, E, Beswick, A, Mestdagh, J. M, Stolte, S, Poisson, L, Pothier, C, Soep, B
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Sprache:eng
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Zusammenfassung:To study the excited state dynamics between a calcium atom and the CH3F molecule, a Ca···CH3F 1:1 complex has been prepared by a supersonic expansion with laser ablation of calcium metal in the gas phase. Tunable laser excitation of these complexes in molecular states correlating to Ca 1P1(4s4p) + CH3F allows observing two competitive channels: the direct dissociation and the reactive channel into CaF* + CH3. The translational recoil, as well as the alignment of the fragments Ca* and CaF* have been analyzed by velocity map imaging and time-of-flight mass spectrometry. This revealed that both the dissociation and reaction processes are quasi direct and are of comparable intensity. We provide a simple interpretation for this process: the electronically excited potential surface of the Ca*···FCH3 complex initiates a fast predissociation from a suspended well to two repulsive surfaces that lead either to Ca 1P1(4s4p) (Ω = 1) + CH3F or to CaF­(2Δ) + CH3.
ISSN:1089-5639
1520-5215
DOI:10.1021/acs.jpca.5b00444