1. Fast peroxy radical isomerization and OH recycling in the reaction of OH radicals with dimethyl sulfide
- Author
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Berndt, T. (T.), Scholz, W. (W.), Mentler, B. (B.), Fischer, L. (L.), Hoffmann, E. H. (E. H.), Tilgner, A. (A.), Hyttinen, N. (N.), Prisle, N. L. (N. L.), Hansel, A. (A.), Herrmann, H. (H.), Berndt, T. (T.), Scholz, W. (W.), Mentler, B. (B.), Fischer, L. (L.), Hoffmann, E. H. (E. H.), Tilgner, A. (A.), Hyttinen, N. (N.), Prisle, N. L. (N. L.), Hansel, A. (A.), and Herrmann, H. (H.)
- 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.
- Published
- 2019