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| Titel |
Contribution of sulfuric acid and oxidized organic compounds to particle formation and growth |
| VerfasserIn |
F. Riccobono, L. Rondo, M. Sipilä, P. Barmet, J. Curtius, J. Dommen, M. Ehn, S. Ehrhart, M. Kulmala  , A. Kürten, J. Mikkilä, P. Paasonen, T. Petäjä, E. Weingärtner, U. Baltensperger |
| 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 ; 12, no. 20 ; Nr. 12, no. 20 (2012-10-19), S.9427-9439 |
| Datensatznummer |
250011516
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| Publikation (Nr.) |
 copernicus.org/acp-12-9427-2012.pdf |
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| Zusammenfassung |
Lack of knowledge about the mechanisms underlying new particle formation and
their subsequent growth is one of the main causes for the large uncertainty
in estimating the radiative forcing of atmospheric aerosols in global
models. We performed chamber experiments designed to study the contributions
of sulfuric acid and organic vapors to the formation and early growth of
nucleated particles. Distinct experiments in the presence of two different
organic precursors (1,3,5-trimethylbenzene and α-pinene) showed the
ability of these compounds to reproduce the formation rates observed in the
low troposphere. These results were obtained measuring the sulfuric acid
concentrations with two chemical ionization mass spectrometers confirming
the results of a previous study which modeled the sulfuric acid
concentrations in presence of 1,3,5-trimethylbenzene.
New analysis methods were applied to the data collected with a condensation
particle counter battery and a scanning mobility particle sizer, allowing
the assessment of the size resolved growth rates of freshly nucleated
particles. The effect of organic vapors on particle growth was investigated
by means of the growth rate enhancement factor (Γ), defined as the
ratio between the measured growth rate in the presence of α-pinene
and the kinetically limited growth rate of the sulfuric acid and water
system. The observed Γ values indicate that the growth is already
dominated by organic compounds at particle diameters of 2 nm. Both the
absolute growth rates and Γ showed a strong dependence on particle
size, supporting the nano-Köhler theory. Moreover, the separation of the
contributions from sulfuric acid and organic compounds to particle growth
reveals that the organic contribution seems to be enhanced by the sulfuric
acid concentration. Finally, the size resolved growth analysis indicates
that both condensation of oxidized organic compounds and reactive uptake
contribute to particle growth. |
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