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Predissociation dynamics of the hydroxyl radical (OH) based on a five-state spectroscopic model

Mitev, Georgi B; Tennyson, Jonathan; Yurchenko, Sergei N; (2024) Predissociation dynamics of the hydroxyl radical (OH) based on a five-state spectroscopic model. The Journal of Chemical Physics , 160 (14) , Article 144110. 10.1063/5.0198241. Green open access

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Abstract

Multi-reference configuration interaction potential energy curves (PECs) and spin-orbit couplings for the X 2Π, A 2Σ+, 1 2Σ-, 1 4Σ-, and 1 4Π states of OH are computed and refined against empirical energy levels and transitions to produce a spectroscopic model. Predissociation lifetimes are determined by discretizing continuum states in the variational method nuclear motion calculation by restricting the calculation to a finite range of internuclear separations. Varying this range gives a series of avoided crossings between quasi-bound states associated with the A 2Σ+ and continuum states, from which predissociation lifetimes are extracted. 424 quasi-bound A 2Σ+ state rovibronic energy levels are analyzed, and 374 predissociation lifetimes are produced, offering good coverage of the predissociation region. Agreement with measured lifetimes is satisfactory, and a majority of computed results were within experimental uncertainty. A previously unreported A 2Σ+ state predissociation channel that goes via X 2Π is identified in the calculations. A Python package, binSLT, produced to calculate predissociation lifetimes, associated line broadening parameters, and lifetime uncertainties is made available. The PECs and other curves from this work will be used to produce a rovibronic ExoMol line list and temperature-dependent photodissociation cross sections for the hydroxyl radical.

Type: Article
Title: Predissociation dynamics of the hydroxyl radical (OH) based on a five-state spectroscopic model
Location: United States
Open access status: An open access version is available from UCL Discovery
DOI: 10.1063/5.0198241
Publisher version: http://dx.doi.org/10.1063/5.0198241
Language: English
Additional information: © 2024 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
Keywords: Ab-initio softwares, Configuration interaction, Complete-active space self-consistent field, Potential energy surfaces, Spin-orbit interactions, Ar predissociation spectroscopy, Photodissociation
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy
URI: https://discovery.ucl.ac.uk/id/eprint/10190774
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