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| Titel |
Water-soluble SOA from Alkene ozonolysis: composition and droplet activation kinetics inferences from analysis of CCN activity |
| VerfasserIn |
A. Asa-Awuku, A. Nenes, S. Gao, R. C. Flagan, J. H. Seinfeld |
| 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 ; 10, no. 4 ; Nr. 10, no. 4 (2010-02-15), S.1585-1597 |
| Datensatznummer |
250008104
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| Publikation (Nr.) |
 copernicus.org/acp-10-1585-2010.pdf |
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| Zusammenfassung |
| Cloud formation characteristics of the water-soluble organic fraction (WSOC) of
secondary organic aerosol (SOA) formed from the ozonolysis of alkene
hydrocarbons (terpinolene, 1-methlycycloheptene and cycloheptene) are
studied. Based on size-resolved measurements of CCN activity (of the pure
and salted WSOC samples) we estimate the average molar volume and surface
tension depression associated with the WSOC using Köhler Theory Analysis
(KTA). Consistent with known speciation, the results suggest that the WSOC
are composed of low molecular weight species, with an effective molar mass
below 200 g mol−1. The water-soluble carbon is also surface-active,
depressing surface tension 10–15% from that of pure water (at
CCN-relevant concentrations). The inherent hygroscopicity parameter, κ, of the
WSOC ranges between 0.17 and 0.25; if surface tension depression and molar
volume effects are considered in κ, a remarkably
constant "apparent" hygroscopicity ~0.3 emerges for all samples
considered. This implies that the volume fraction of soluble material in the
parent aerosol is the key composition parameter required for prediction of
the SOA hygroscopicity, as shifts in molar volume across samples are
compensated by changes in surface tension. Finally, using "threshold
droplet growth analysis", the water-soluble organics in all samples
considered do not affect CCN activation kinetics. |
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