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Title:ULTRAVIOLET PHOTOABSORPTION OF SO ISOTOPOLOGUES AND THE B 3Σ− AND C 3Π STATES
Author(s):Heays, Alan
Contributor(s):Gibson, Stephen T; Lewis, Brenton R; de Oliveira, Nelson ; Lyons, James R; Stark, Glenn
Subject(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.
Issue Date:2019-06-21
Publisher:International Symposium on Molecular Spectroscopy
Genre:Conference Paper / Presentation
Type:Text
Language:English
URI:http://hdl.handle.net/2142/104371
DOI:10.15278/isms.2019.FB09
Rights Information:Copyright 2019 Alan Heays
Date Available in IDEALS:2019-07-15
2020-01-25


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