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| Titel |
From molecular clusters to nanoparticles: second-generation ion-mediated nucleation model |
| VerfasserIn |
F. Yu |
| 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 ; 6, no. 12 ; Nr. 6, no. 12 (2006-11-15), S.5193-5211 |
| Datensatznummer |
250004179
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| Publikation (Nr.) |
 copernicus.org/acp-6-5193-2006.pdf |
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| Zusammenfassung |
| Ions, which are generated in the atmosphere by galactic
cosmic rays and other ionization sources, may play an important role in the
formation of atmospheric aerosols. In the paper, a new second-generation
ion-mediated nucleation (IMN) model is presented. The new model explicitly
treats the evaporation of neutral and charged clusters and it describes the
evolution of the size spectra and composition of both charged and neutral
clusters/particles ranging from small clusters of few molecules to large
particles of several micrometers in diameter. Schemes used to calculate the
evaporation coefficients for small neutral and charged clusters are
consistent with the experimental data within the uncertainty range. The
present IMN model, which is size-, composition-, and type-resolved, is a
powerful tool for investigating the dominant mechanisms and key parameters
controlling the formation and subsequent growth of nanoparticles in the
atmosphere. This model can be used to analyze simultaneous measurements of
the ion-mobility spectra and particle size distributions, which became
available only recently. General features of the spectra for ions smaller
than the critical size, size-dependent fractions of charged nanoparticles,
and asymmetrical charging of freshly nucleated particles predicted by the
new IMN model are consistent with recent measurements. Results obtained
using the second generation IMN model, in which the most recent
thermodynamic data for neutral and charged H2SO4-H2O clusters
were used, suggest that ion-mediated nucleation of H2SO4-H2O
can lead to a significant production of new particles in the lower
atmosphere (including the boundary layer) under favorable conditions. It has
been shown that freshly nucleated particles of few nanometers in size can
grow by the condensation of low volatile organic compounds to the size of
cloud condensation nuclei. In such cases, the chemical composition of
nucleated particles larger than ~10 nm is dominated by organics. |
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