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| Titel |
Hydration increases the lifetime of HSO5 and enhances its ability to act as a nucleation precursor – a computational study |
| VerfasserIn |
T. Kurtén, T. Berndt, F. Stratmann |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 9, no. 10 ; Nr. 9, no. 10 (2009-05-25), S.3357-3369 |
| Datensatznummer |
250007306
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| Publikation (Nr.) |
 copernicus.org/acp-9-3357-2009.pdf |
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| Zusammenfassung |
| Recent experimental findings indicate that HSO5 radicals may
play a key role in the nucleation of atmospheric SO2 oxidation
products. HSO5 radicals are metastable intermediates formed in the
SO2 oxidation process, and their stability and lifetime are, at
present, highly uncertain. Previous high-level computational studies have
predicted rather low stabilities for HSO5 with respect to dissociation
into SO3+HO2, and have predicted the net reaction HSO3+OH→SO3+HO2
to be slightly exothermal. However, these studies
have not accounted for hydration of HSO5 or its precursor HSO3. In
this study, we have estimated the effect of hydration on the stability and
lifetime of HSO5 using the advanced quantum chemical methods CCSD(T)
and G3B3. We have computed formation energies and free energies for mono-
and dihydrates of OH, HSO3, HSO5, SO3 and HO2, and also
reanalyzed the individual steps of the HSO3+O2→HSO5→SO3+HO2 reaction at a higher level of theory than
previously published. Our results indicate that hydration is likely to
significantly prolong the lifetime of the HSO5 intermediate in
atmospheric conditions, thus increasing the probability of reactions that
form products with more than one sulfur atom. Kinetic modeling indicates
that these results may help explain the experimental observations that a
mixture of sulfur-containing products formed from SO2 oxidation by OH
radicals nucleates much more effectively than sulfuric acid taken from a
liquid reservoir. |
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