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| Titel |
Characterization of oligomers from methylglyoxal under dark conditions: a pathway to produce secondary organic aerosol through cloud processing during nighttime |
| VerfasserIn |
F. Yasmeen, N. Sauret, J.-F. Gal, P.-C. Maria, L. Massi, W. Maenhaut, M. Claeys |
| 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 ; 10, no. 8 ; Nr. 10, no. 8 (2010-04-23), S.3803-3812 |
| Datensatznummer |
250008373
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| Publikation (Nr.) |
 copernicus.org/acp-10-3803-2010.pdf |
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| Zusammenfassung |
| Aqueous-phase oligomer formation from methylglyoxal, a major atmospheric
photooxidation product, has been investigated in a simulated cloud matrix
under dark conditions. The aim of this study was to explore an additional
pathway producing secondary organic aerosol (SOA) through cloud processes
without participation of photochemistry during nighttime. Indeed,
atmospheric models still underestimate SOA formation, as field measurements
have revealed more SOA than predicted. Soluble oligomers (n = 1–8) formed in
the course of acid-catalyzed aldol condensation and acid-catalyzed hydration
followed by acetal formation have been detected and characterized by
positive and negative ion electrospray ionization mass spectrometry. Aldol
condensation proved to be a favorable mechanism under simulated cloud
conditions, while hydration/acetal formation was found to strongly depend on
the pH of the system and only occurred at a pH<3.5. No evidence was found
for formation of organosulfates. The aldol oligomer series starts with a
β-hydroxy ketone via aldol condensation, where oligomers are formed
by multiple additions of C3H4O2 units (72 Da) to the parent
β-hydroxy ketone. Ion trap mass spectrometry experiments were
performed to structurally characterize the major oligomer species. A
mechanistic pathway for the growth of oligomers under cloud conditions and
in the absence of UV-light and OH radicals, which could substantially
enhance in-cloud SOA yields, is proposed here for the first time. |
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