Isotope effect in the carbonyl sulfide reaction with O(3P)

Shohei Hattori, Johan Albrecht Schmidt, Denise W. Mahler, Sebastian O. Danielache, Matthew Stanley Johnson, Naohiro Yoshida

13 Citations (Scopus)

Abstract

The sulfur kinetic isotope effect (KIE) in the reaction of carbonyl sulfide (OCS) with O(3P) was studied in relative rate experiments at 298 ± 2 K and 955 ± 10 mbar. The reaction was carried out in a photochemical reactor using long path FTIR detection, and data were analyzed using a nonlinear least-squares spectral fitting procedure with line parameters from the HITRAN database. The ratio of the rate of the reaction of OC 34S relative to OC32S was found to be 0.9783 ± 0.0062 (34ε = (-21.7 ± 6.2)‰). The KIE was also calculated using quantum chemistry and classical transition state theory; at 300 K, the isotopic fractionation was found to be 34Îμ = ε14.8‰. The OCS sink reaction with O(3P) cannot explain the large fractionation in 34S, over +73‰, indicated by remote sensing data. In addition, 34Îμ in OCS photolysis and OH oxidation are not larger than 10‰, indicating that, on the basis of isotopic analysis, OCS is an acceptable source of background stratospheric sulfate aerosol.

Original languageEnglish
JournalJournal of Physical Chemistry Part A: Molecules, Spectroscopy, Kinetics, Environment and General Theory
Volume116
Issue number14
Pages (from-to)3521-3526
Number of pages6
ISSN1089-5639
DOIs
Publication statusPublished - 12 Apr 2012

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