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| Titel |
Fast photolysis of carbonyl nitrates from isoprene |
| VerfasserIn |
J.-F. Müller, J. Peeters, T. Stavrakou |
| 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 ; 14, no. 5 ; Nr. 14, no. 5 (2014-03-11), S.2497-2508 |
| Datensatznummer |
250118473
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| Publikation (Nr.) |
 copernicus.org/acp-14-2497-2014.pdf |
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| Zusammenfassung |
| Photolysis is shown to be a major sink for isoprene-derived carbonyl nitrates, which constitute
an important component of the total organic nitrate pool over vegetated areas. Empirical evidence
from published laboratory studies on the absorption cross sections and photolysis rates of
α-nitrooxy ketones suggests that the presence of the nitrate
group (i) greatly enhances the absorption cross sections and (ii) facilitates
dissociation to a point that the photolysis quantum yield is close to unity, with O–NO2
dissociation as a likely major channel. On this basis, we provide new recommendations for
estimating the cross sections and photolysis rates of carbonyl nitrates. The newly
estimated photo rates are validated using a chemical box model against measured temporal
profiles of carbonyl nitrates in an isoprene oxidation experiment by Paulot et al. (2009).
The comparisons for ethanal nitrate and for the sum of methacrolein- and methyl vinyl ketone
nitrates strongly supports our assumptions of large cross-section enhancements and
a near-unit quantum yield for these compounds. These findings have significant atmospheric
implications: the photorates of key carbonyl nitrates from isoprene are estimated to be
typically between ~ 3 and 20 times higher than their sink due to reaction with OH in
relevant atmospheric conditions. Moreover, since the reaction is expected to release NO2,
photolysis is especially effective in depleting the total organic nitrate pool. |
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