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Title:A SPECTROSCOPIC PERTURBATION ORIGIN FOR SULFUR MASS INDEPENDENT FRACTIONATION VIA THE B-X SYSTEM OF S2
Author(s):Hull, Alexander W.
Contributor(s):Field, Robert W.; Ono, Shuhei
Subject(s):Atmospheric science
Abstract:The Great Oxygenation Event (GOE), the introduction of O$_{2}$ into the Earth’s atmosphere approximately 2.4 billion years ago, is a critical signpost in the development of life on Earth. The vanishing of sulfur isotope anomalies, called Sulfur Mass-Independent Fractionation (S-MIF), in the rock record is thought to be correlated with oxygenation of the early atmosphere. However, the mechanism for the generation of S-MIF in an anoxic atmosphere is unknown. Here, I propose a mechanism that involves spectroscopic perturbations in the B-X UV band system of S$_{2}$. This proposal is based on a global deperturbation analysis done by Green and Western\footnote{M.E. Green, C.M. Western, A deperturbation analysis of the B $^{3}$$\Sigma$$_{u}$$^-$ (v' = 0-6) and the B" $^{3}$$\Pi$$_{u}$ (v' = 2-12) states of S$_{2}$, J. Chem. Phys. 104 (3) (1996) 848-864.} \footnote{M.E. Green, C.M. Western, Upper vibrational states of the B" $^{3}$$\Pi$$_{u}$ state of $^{32}$S$_{2}$, J. Chem. Soc., Faraday Trans. 93 (3) (1997) 365-372.} and work that I presented previously at this conference in 2015 (MG12) and 2016 (MG08). Specifically, perturbations of the “bright” B state by a “dark” B” state cause some isotopologues to have longer average excited state lifetimes than others. I demonstrate a difference between the shorter-lifetime symmetric (e.g. $^{32}$S-$^{32}$S) isotopologues of S2, for which nuclear permutation symmetry causes half of the rotational lines to be missing, and the longer-lifetime asymmetric isotopologues (e.g. $^{33}$S-$^{32}$S). I also comment on general features of the B/B” system of S$_{2}$ that make it uniquely well-suited to generate a large MIF isotope effect.
Issue Date:06/22/18
Publisher:International Symposium on Molecular Spectroscopy
Citation Info:APS
Genre:Conference Paper / Presentation
Type:Text
Language:English
URI:http://hdl.handle.net/2142/100717
DOI:10.15278/isms.2018.FF03
Other Identifier(s):FF03
Date Available in IDEALS:2018-08-17
2018-12-12


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