Chapter 5 Photolysis of Long-Lived Predissociative Molecules as a Source of Mass-Independent Isotope Fractionation: The Example of SO2

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22 Scopus citations

Abstract

Laboratory experiments have demonstrated that a mass-independent fractionation (MIF) signature is present in elemental sulfur produced during SO2 photolysis, but the underlying mechanism remains unknown. I report here the results of chemical kinetics modeling of self-shielding during photodissociation of SO2 in the over(C, ̃)1 B2 - over(X, ̃)1 A1 bands from 190 to 220 nm. This band system is dominated by a bending mode progression that produces shifts in the absorption spectrum upon sulfur isotope substitution. Self-shielding in the rotationally-resolved lines of 32SO2 produces MIF signatures in SO and residual SO2. Using approximate synthetic spectra for the sulfur isotopologues of SO2, I show that SO2 photolysis yields a sulfur MIF signature that can account for much of the laboratory MIF measured, and is in qualitative agreement with Δ33 S and Δ36 S values observed in Archean rocks.

Original languageEnglish (US)
Title of host publicationApplications of Theoretical Methods to Atmospheric Science
EditorsMichael Goodsite, Matthew Johnson
Pages57-74
Number of pages18
DOIs
StatePublished - May 6 2008
Externally publishedYes

Publication series

NameAdvances in Quantum Chemistry
Volume55
ISSN (Print)0065-3276

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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    Lyons, J. R. (2008). Chapter 5 Photolysis of Long-Lived Predissociative Molecules as a Source of Mass-Independent Isotope Fractionation: The Example of SO2. In M. Goodsite, & M. Johnson (Eds.), Applications of Theoretical Methods to Atmospheric Science (pp. 57-74). (Advances in Quantum Chemistry; Vol. 55). https://doi.org/10.1016/S0065-3276(07)00205-5