OCS photolytic isotope effects from first principles: sulfur and carbon isotopes, temperature dependence and implications for the stratosphere
-
Published:2013-02-06
Issue:3
Volume:13
Page:1511-1520
-
ISSN:1680-7324
-
Container-title:Atmospheric Chemistry and Physics
-
language:en
-
Short-container-title:Atmos. Chem. Phys.
Author:
Schmidt J. A.ORCID, Johnson M. S.ORCID, Hattori S.ORCID, Yoshida N.ORCID, Nanbu S., Schinke R.
Abstract
Abstract. The isotopic fractionation in OCS photolysis is studied theoretically from first principles. UV absorption cross sections for OCS, OC33S, OC34S, OC36S and O13CS are calculated using the time-depedent quantum mechanical formalism and a recently developed ab-initio description of the photodissociation of OCS which takes into account the lowest four singlet and lowest four triplet electronic states. The calculated isotopic fractionations as a function of wavelength are in good agreement with recent measurements by Hattori et al. (2011) and indicate that photolysis leads to only a small enrichment of 34S in the remaining OCS. The photodissociation dynamics provide strong evidence that the photolysis quantum yield is unity at all wavelengths for atmospheric UV excitation, for all isotopologues. A simple stratospheric model is constructed taking into account the main sink reactions of OCS and it is found that overall stratospheric removal slightly favors light OCS in constrast to the findings of Leung et al. (2002). These results show, based on isotopic considerations, that OCS is an acceptable source of background stratosperic sulfate aerosol in agreement with a recent model study of of Brühl et al. (2012). The 13C isotopic fractionation due to photolysis of OCS in the upper stratosphere is significant and will leave a clear signal in the remaining OCS making it a candidate for tracing using the ACE-FTS and MIPAS data sets.
Funder
European Commission
Publisher
Copernicus GmbH
Subject
Atmospheric Science
Reference59 articles.
1. Barkley, M. P., Palmer, P. I., Boone, C. D., Bernath, P. F., and Suntharalingam, P.: Global distributions of carbonyl sulfide in the upper troposphere and stratosphere, Geophys. Res. Lett., 35, L14810, https://doi.org/10.1029/2008GL034270, 2008. 2. Belafhal, A., Fayt, A., and Guelachvili, G.: Fourier transform spectroscopy of carbonyl sulfide from 1800 to 3120 cm^{-1}: the normal species, J. Mol. Struct., 174, 1–19, https://doi.org/10.1006/jmsp.1995.1264, 1995. 3. Belviso, S., Mihalopoulos, N., and Nguyen, B. C.: The supersaturation of carbonyl sulfide (OCS) in rain waters, Atmos. Environ., 21, 1363–1367, https://doi.org/10.1016/0004-6981(67)90083-2, 1967. 4. Brühl, C., Lelieveld, J., Crutzen, P. J., and Tost, H.: The role of carbonyl sulphide as a source of stratospheric sulphate aerosol and its impact on climate, Atmos. Chem. Phys., 12, 1239–1253, https://doi.org/10.5194/acp-12-1239-2012, 2012. 5. Castleman, A. W., Munkelwitz, H. R., and Manowitz, B.: Isotopic studies of the sulfur component of the stratospheric aerosol layer, Tellus B, 26, 222–234, available at: http://www.tellusb.net/index.php/tellusb/article/view/13739/15505, 1974.
Cited by
23 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献
|
|