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| Titel |
A mass spectrometric study of secondary organic aerosols formed from the photooxidation of anthropogenic and biogenic precursors in a reaction chamber |
| VerfasserIn |
M. R. Alfarra, D. Paulsen, M. Gysel, A. A. Garforth, J. Dommen, A. S. H. Prévôt, D. R. Worsnop, U. Baltensperger, H. Coe |
| 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 (2006-11-20), S.5279-5293 |
| Datensatznummer |
250004184
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| Publikation (Nr.) |
 copernicus.org/acp-6-5279-2006.pdf |
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| Zusammenfassung |
| An Aerodyne Aerosol Mass Spectrometer (AMS) has been utilised to
provide on-line measurements of the mass spectral signatures and
mass size distributions of the oxidation products resulting from
irradiating 1,3,5-trimethylbenzene (1,3,5-TMB) and α-pinene,
separately, in the presence of nitrogen oxide, nitrogen dioxide and
propene in a reaction chamber. Mass spectral results indicate that
both precursors produce SOA with broadly similar chemical
functionality of a highly oxidised nature. However, significant
differences occur in the minor mass spectral fragments for the SOA
in the two reaction systems, indicating that they have different
molecular composition. Nitrogen-containing organic compounds have
been observed in the photooxidation products of both precursors, and
their formation appeared to be controlled by the temporal
variability of NOx. Although the overall fragmentation
patterns of the photooxidation products in both systems did not
change substantially over the duration of each experiment, the
contribution of some individual mass fragments to total mass
appeared to be influenced by the irradiation time. The effective
densities of the 1,3,5-TMB and α-pinene SOA particles were
determined for various particle sizes using the relationship between
mobility and vacuum aerodynamic diameters. The effective density for
the 1,3,5-TMB SOA ranged from 1.35–1.40 g/cm3, while that for
α-pinene SOA ranged from 1.29–1.32 g/cm3. The
determined effective densities did not show dependence on
irradiation time. Results suggest that further chemical processing
of SOA takes place in the real atmosphere, as neither the α-pinene
nor the 1,3,5-TMB experimental results reproduce the right
relative product distribution between carbonyl-containing and
multifunctional carboxylic acid species measured at ambient
locations influenced by aged continental organic aerosols. |
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