Ultraviolet photoabsorption of SO isotopologues and the B 3Σ‒ and C 3Σ states

Heays, Alan

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https://hdl.handle.net/2142/104371 Copy

Description

Title

Ultraviolet photoabsorption of SO isotopologues and the B 3Σ‒ and C 3Σ states

Author(s)

Heays, Alan

Contributor(s)

• Gibson, Stephen T.
• Lewis, Brenton R.
• de Oliveira, Nelson
• Lyons, James R.
• Stark, Glenn

Issue Date

2019-06-21

Keyword(s)

Atmospheric science

Abstract

The sulphur-monoxide $B\,{}^3\Sigma^-(v\ge4)$ levels are known to be strongly affected by vibrationally-dependent predissociation and local energy perturbations (Liu et al. 2006 JMS 238:213). The isotope-dependence of this predissociation and the SO photodissociation cross section is a candidate atmospheric-source for explaining the anomalous ${}^{32}$S/${}^{33}$S/${}^{34}$S/${}^{36}$S isotopic fractionation found in 2.5Ga old sedimentary material (Ono 2017 Annu. Rev. Earth Pl. Sc. 45:301). We have recorded new photoabsorption spectra between 195 and 230 nm to determine spectroscopic constants, predissociation linewidths, and transition strengths for the excited $B\,{}^3\Sigma^-(v=4-17)$ levels of ${}^{32}$S${}^{16}$O, ${}^{33}$S${}^{16}$O, and ${}^{34}$S${}^{16}$O. The $C\,{}^3\Pi$ state is also observed and perturbs $B\,{}^3\Sigma^-(v=4-17)$ through spin-orbit interaction. $B\,{}^3\Sigma^-$ and $C\,{}^3\Pi$ potential-energy curves, electronic transition moments, and a global spin-orbit interaction are deduced from the new data so that it may be extrapolated to the rare ${}^{36}$S${}^{16}$O isotopologue. We use the new cross sections to explore the potential for isotope-dependent photodissociation of SO in the ancient-Earth atmosphere due to structured solar UV radiation and atmospheric opacity.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

eng

Permalink

http://hdl.handle.net/2142/104371

DOI

https://doi.org/10.15278/isms.2019.FB09

Copyright and License Information

Copyright 2019 Alan Heays

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