Fast peroxy radical isomerization and OH recycling in the reaction of OH radicals with dimethyl sulfide
Berndt, T.; Scholz, W.; Mentler, B.; Fischer, L.; Hoffmann, E. H.; Tilgner, A.; Hyttinen, N.; Prisle, N. L.; Hansel, A.; Herrmann, H. (2019-10-07)
T. Berndt et al. Fast peroxy radical isomerization and OH recycling in the reaction of OH radicals with dimethyl sulfide. J. Phys. Chem. Lett. 2019, 10, 6478−6483. https://doi.org/10.1021/acs.jpclett.9b02567
© 2019 American Chemical Society. This document is the Accepted Manuscript version of a Published Work that appeared in final form in Journal of Physical Chemistry Letters, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/acs.jpclett.9b02567
https://rightsstatements.org/vocab/InC/1.0/
https://urn.fi/URN:NBN:fi-fe2019101733541
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Abstract
Dimethyl sulfide (DMS), produced by marine organisms, represents the most abundant, biogenic sulfur emission into the Earth’s atmosphere. The gas-phase degradation of DMS is mainly initiated by the reaction with the OH radical forming first CH3SCH2O2 radicals from the dominant H-abstraction channel. It is experimentally shown that these peroxy radicals undergo a two-step isomerization process finally forming a product consistent with the formula HOOCH2SCHO. The isomerization process is accompanied by OH recycling. The rate-limiting first isomerization step, CH3SCH2O2 → CH2SCH2OOH, followed by O2 addition, proceeds with k = (0.23 ± 0.12) s–1 at 295 ± 2 K. Competing bimolecular CH3SCH2O2 reactions with NO, HO2, or RO2 radicals are less important for trace-gas conditions over the oceans. Results of atmospheric chemistry simulations demonstrate the predominance (≥95%) of CH3SCH2O2 isomerization. The rapid peroxy radical isomerization, not yet considered in models, substantially changes the understanding of DMS’s degradation processes in the atmosphere.
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