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| Titel |
Daytime tropospheric loss of hexanal and trans-2-hexenal: OH kinetics and UV photolysis |
| VerfasserIn |
E. Jimenez, B. Lanza, E. Martínez, J. Albaladejo |
| 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 ; 7, no. 6 ; Nr. 7, no. 6 (2007-03-22), S.1565-1574 |
| Datensatznummer |
250004829
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| Publikation (Nr.) |
 copernicus.org/acp-7-1565-2007.pdf |
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| Zusammenfassung |
| The ultraviolet (λ=250–370 nm) photolysis and the OH-initiated
oxidation of hexanal and trans-2-hexenal, which are relevant atmospheric
processes, have been investigated at room temperature and as a function of
temperature (T=263–353 K), respectively. This kinetic study as a function
of temperature is reported here for the first time. Absolute absorption
cross sections (σλ) were obtained using a
recently built system operating in the UV region. The obtained σλ
allowed the estimation of the photolysis rates (J) across the
troposphere. Kinetic measurements of the gas-phase reaction of hydroxyl
radicals (OH) with hexanal and trans-2-hexenal were performed by using the
laser pulsed photolysis/laser-induced fluorescence technique. Rate
coefficients kOH for both aldehydes were determined at temperatures
between 263 and 353 K at 50 Torr in helium or argon bath gases. The
temperature dependence of kOH for both aldehydes was found to be
slightly negative. The tropospheric lifetime of hexanal and
trans-2-hexenal due to the chemical removal by OH radicals has been
estimated across the troposphere. The loss rate due to the OH chemical
removal was compared with the estimated photolysis rates. Our results show
that OH-reaction is the main loss process for these aldehydes in the
troposphere, although photolysis is not negligible for hexanal. |
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