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| Titel |
Isoprene oxidation by nitrate radical: alkyl nitrate and secondary organic aerosol yields |
| VerfasserIn |
A. W. Rollins, A. Kiendler-Scharr, J. L. Fry, T. Brauers, S. S. Brown, H.-P. Dorn, W. P. Dubé, H. Fuchs, A. Mensah, T. F. Mentel, F. Rohrer, R. Tillmann, R. Wegener, P. J. Wooldridge, R. C. Cohen |
| 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. 18 ; Nr. 9, no. 18 (2009-09-15), S.6685-6703 |
| Datensatznummer |
250007626
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| Publikation (Nr.) |
 copernicus.org/acp-9-6685-2009.pdf |
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| Zusammenfassung |
| Alkyl nitrates and secondary organic aerosol (SOA) produced during the
oxidation of isoprene by nitrate radicals has been observed in the SAPHIR
(Simulation of Atmospheric PHotochemistry In a large Reaction Chamber)
chamber. A 16 h dark experiment was conducted with temperatures at
289–301 K, and maximum concentrations of 11 ppb isoprene, 62.4 ppb O3
and 31.1 ppb NOx. We find the yield of nitrates is 70±8%
from the isoprene + NO3 reaction, and the yield for secondary dinitrates
produced in the reaction of primary isoprene nitrates with NO3 is
40±20%. We find an effective rate constant for reaction of NO3 with
the group of first generation oxidation products to be
7×10−14 molecule−1 cm3 s−1. At the low total
organic aerosol concentration in the chamber (max=0.52 μg m−3) we
observed a mass yield (ΔSOA mass/Δisoprene mass) of 2% for the
entire 16 h experiment. However a comparison of the timing of the observed
SOA production to a box model simulation of first and second generation
oxidation products shows that the yield from the first generation products
was <0.7% while the further oxidation of the initial products leads to a
yield of 14% (defined as ΔSOA/Δisoprene2x where
Δisoprene2x is the mass of isoprene which reacted twice
with NO3). The SOA yield of 14% is consistent with equilibrium
partitioning of highly functionalized C5 products of isoprene oxidation. |
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