Signature of a conical intersection in the dissociative photoionization of formaldehyde
- 8 April 2020
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Physical Chemistry Chemical Physics
- Vol. 22 (23), 12886-12893
- https://doi.org/10.1039/d0cp01267j
Abstract
The valence-shell photoionization of formaldehyde is investigated by means of combining Photo-Electron Photo-Ion COincidence (PEPICO) experiments and ab initio calculations. The formation of three ion fragments: HCO+, CO+ and H+ 2, via dissociative photoionization following excitation at 17 eV is discussed. The experimental results consisting of electron–ion kinetic energy correlation diagrams for the corresponding coincident events, i.e. (HCO+, e−), (CO+, e−) and (H+ 2, e−), as well as the fragment abundance as a function of the binding energy, are complemented by high level electronic structure calculations including potential energy curves and on-the-fly trajectories. The results are consistent with a main relaxation process via internal conversion into rovibrationally excited levels of the H2CO+ ground state, followed by statistical dissociation, preferentially into HCO+. The analysis of the experimental results reveals nevertheless the signature of a conical intersection controlling the dynamics and favoring dissociation into the molecular channel, CO+ + H2. In addition, the minor formation of the H+ 2 ion is suggested to occur through a roaming pathway on the cation excited state.Keywords
Funding Information
- Ministerio de Ciencia e Innovación (PGC2018-096444-B-I00)
- H2020 Marie Skłodowska-Curie Actions (842539 (ATTO-CONTROL))
- Secretaría de Estado de Investigación, Desarrollo e Innovación (CTQ2015-65033-P)
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