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| Titel |
Aerosol charging state at an urban site: new analytical approach and implications for ion-induced nucleation |
| VerfasserIn |
S. Gagné, J. Leppä, T. Petäjä, M. J. McGrath, M. Vana, V.-M. Kerminen, L. Laakso, M. Kulmala  |
| 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. 10 ; Nr. 12, no. 10 (2012-05-25), S.4647-4666 |
| Datensatznummer |
250011173
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| Publikation (Nr.) |
 copernicus.org/acp-12-4647-2012.pdf |
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| Zusammenfassung |
| The charging state of aerosol populations was determined using an Ion-DMPS in
Helsinki, Finland between December 2008 and February 2010. We extrapolated
the charging state and calculated the ion-induced nucleation fraction to be
around 1.3 % ± 0.4 % at 2 nm and 1.3 % ± 0.5 % at
1.5 nm, on average. We present a new method to retrieve the average charging
state for a new particle formation event, at a given size and polarity. We
improve the uncertainty assessment and fitting technique used previously with
an Ion-DMPS. We also use a new theoretical framework that allows for
different concentrations of small ions for different polarities (polarity
asymmetry). We extrapolate the ion-induced fraction using polarity symmetry
and asymmetry. Finally, a method to calculate the growth rates from the
behaviour of the charging state as a function of the particle diameter using
polarity symmetry and asymmetry is presented and used on a selection of new
particle formation events. |
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