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| Titel |
Internal mixing of the organic aerosol by gas phase diffusion of semivolatile organic compounds |
| VerfasserIn |
C. Marcolli, B. P. Luo, Th. Peter, F. G. Wienhold |
| 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 ; 4, no. 11/12 ; Nr. 4, no. 11/12 (2004-12-20), S.2593-2599 |
| Datensatznummer |
250001433
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| Publikation (Nr.) |
 copernicus.org/acp-4-2593-2004.pdf |
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| Zusammenfassung |
| This paper shows that most of the so far identified constituents of the
tropospheric organic particulate matter belong to a semivolatile fraction for
which gas phase diffusion in the lower troposphere is sufficiently fast to
establish thermodynamic equilibrium between aerosol particles. For the first
time analytical expressions for this process are derived. Inspection of vapor
pressure data of a series of organic substances allows a rough estimate for
which substances this mixing process must be considered. As general benchmarks
we conclude that for typical aerosol radii between 0.1 and 1 µm this
mixing process is efficient at 25°C for polar species with molecular
weights up to 200 and for non-polar species up to 320. At −10°C,
these values are shifted to 150 for polar and to 270 for non-polar substances.
The extent of mixing of this semivolatile fraction is governed by equilibrium
thermodynamics, leading to a selectively, though not completely, internally
mixed aerosol. The internal mixing leads to a systematic depression of melting
and deliquescence points of organic and mixed organic/inorganic aerosols, thus
leading to an aerosol population in the lower troposphere which is
predominantly liquid. |
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