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| Titel |
Isoprene photooxidation: new insights into the production of acids and organic nitrates |
| VerfasserIn |
F. Paulot, J. D. Crounse, H. G. Kjaergaard, J. H. Kroll, J. H. Seinfeld, P. O. Wennberg |
| 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. 4 ; Nr. 9, no. 4 (2009-02-23), S.1479-1501 |
| Datensatznummer |
250006939
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| Publikation (Nr.) |
 copernicus.org/acp-9-1479-2009.pdf |
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| Zusammenfassung |
| We describe a nearly explicit chemical mechanism for isoprene photooxidation
guided by chamber studies that include time-resolved observation of an
extensive suite of volatile compounds. We provide new constraints on the
chemistry of the poorly-understood isoprene δ-hydroxy channels, which
account for more than one third of the total isoprene carbon flux and a
larger fraction of the nitrate yields. We show that the cis branch
dominates the chemistry of the δ-hydroxy channel with less than 5% of
the carbon following the trans branch. The modelled yield of
isoprene nitrates is 12±3% with a large difference between the
δ and β branches. The oxidation of these nitrates releases about
50% of the NOx. Methacrolein nitrates (modelled yield
~15±3% from methacrolein) and methylvinylketone nitrates
(modelled yield ~11±3% yield from methylvinylketone) are also
observed. Propanone nitrate, produced with a yield of 1% from isoprene,
appears to be the longest-lived nitrate formed in the total oxidation of
isoprene. We find a large molar yield of formic acid and suggest a novel
mechanism leading to its formation from the organic nitrates. Finally, the
most important features of this mechanism are summarized in a condensed
scheme appropriate for use in global chemical transport models. |
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