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| Titel |
Formation and chemical aging of secondary organic aerosol during the β-caryophyllene oxidation |
| VerfasserIn |
A. Tasoglou, S. N. Pandis |
| 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 ; 15, no. 11 ; Nr. 15, no. 11 (2015-06-02), S.6035-6046 |
| Datensatznummer |
250119783
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| Publikation (Nr.) |
 copernicus.org/acp-15-6035-2015.pdf |
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| Zusammenfassung |
| The secondary organic aerosol (SOA) production during the oxidation of β-caryophyllene by ozone (O3) and hydroxyl radicals (OH) and the
subsequent chemical aging of the products during reactions with OH were
investigated. Experiments were conducted with ozone and with hydroxyl radicals at low
NOx (zero added NOx) and at high NOx (hundreds of parts per billion). The SOA
mass yield at 10 μg m−3 of organic aerosol was 27% for the
ozonolysis, 20% for the reaction with OH at low NOx, and 38% at
high NOx under dry conditions, 20 °C, and ozone excess.
Parameterizations of the fresh SOA yields have been developed. The average
fresh SOA atomic O : C ratio varied from 0.24 to 0.34 depending on the
oxidant and the NOx level, while the H : C ratio was close to 1.5 for
all systems examined. An average density of
1.06 ± 0.1 μg m−3 of the β-caryophyllene SOA was
estimated. The exposure to UV light had no effect on the β-caryophyllene SOA concentration and aerosol mass spectrometer (AMS) measurements. The chemical aging of the β-caryophyllene SOA produced was
studied by exposing the fresh SOA to high concentrations
(107 molecules cm−3) of OH for several hours. These additional
reactions increased the SOA concentration by 15–40% and O : C by
approximately 25%. A limited number of experiments suggested that there
was a significant impact of the relative humidity on the chemical aging of
the SOA. The evaporation rates of β-caryophyllene SOA were quantified
by using a thermodenuder allowing us to estimate the corresponding volatility
distributions and effective vaporization enthalpies. |
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