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| Titel |
Glyoxal uptake on ammonium sulphate seed aerosol: reaction products and reversibility of uptake under dark and irradiated conditions |
| VerfasserIn |
M. M. Galloway, P. S. Chhabra, A. W. H. Chan, J. D. Surratt, R. C. Flagan, J. H. Seinfeld, F. N. Keutsch |
| 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 ; 9, no. 10 ; Nr. 9, no. 10 (2009-05-25), S.3331-3345 |
| Datensatznummer |
250007304
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| Publikation (Nr.) |
 copernicus.org/acp-9-3331-2009.pdf |
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| Zusammenfassung |
| Chamber studies of glyoxal uptake onto ammonium sulphate aerosol were
performed under dark and irradiated conditions to gain further insight into
processes controlling glyoxal uptake onto ambient aerosol. Organic fragments
from glyoxal dimers and trimers were observed within the aerosol under dark
and irradiated conditions. Glyoxal monomers and oligomers were the dominant
organic compounds formed under the conditions of this study; glyoxal oligomer
formation and overall organic growth were found to be reversible under dark
conditions. Analysis of high-resolution time-of-flight aerosol mass spectra
provides evidence for irreversible formation of carbon-nitrogen (C-N)
compounds in the aerosol. We have identified 1H-imidazole-2-carboxaldehyde as
one C-N product. To the authors' knowledge, this is the first time
C-N compounds resulting from condensed phase reactions with ammonium
sulphate seed have been detected in aerosol. Organosulphates were not
detected under dark conditions. However, active photochemistry was found to
occur within aerosol during irradiated experiments. Carboxylic acids and
organic esters were identified within the aerosol. An organosulphate, which
had been previously assigned as glyoxal sulphate in ambient samples and
chamber studies of isoprene oxidation, was observed only in the irradiated
experiments. Comparison with a laboratory synthesized standard and chemical
considerations strongly suggest that this organosulphate is glycolic acid
sulphate, an isomer of the previously proposed glyoxal sulphate. Our study
shows that reversibility of glyoxal uptake should be taken into account in
SOA models and also demonstrates the need for further investigation of
C-N compound formation and photochemical processes, in particular
organosulphate formation. |
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