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| Titel |
Chemical characterization of SOA formed from aqueous-phase reactions of phenols with the triplet excited state of carbonyl and hydroxyl radical |
| VerfasserIn |
L. Yu, J. Smith, A. Laskin, C. Anastasio, J. Laskin, Q. Zhang |
| 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 ; 14, no. 24 ; Nr. 14, no. 24 (2014-12-23), S.13801-13816 |
| Datensatznummer |
250119267
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| Publikation (Nr.) |
 copernicus.org/acp-14-13801-2014.pdf |
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| Zusammenfassung |
| Phenolic compounds, which are emitted in significant amounts from biomass
burning, can undergo fast reactions in atmospheric aqueous phases to form
secondary organic aerosol (aqSOA). In this study, we investigate the
reactions of phenol (compound with formula C6H5OH)), guaiacol
(2-methoxyphenol), and syringol (2,6-dimethoxyphenol) with two major
aqueous-phase oxidants – the triplet excited states of an aromatic carbonyl
(3C*) and hydroxyl radical (· OH). We thoroughly
characterize the low-volatility species produced from these reactions and
interpret their formation mechanisms using aerosol mass spectrometry (AMS),
nanospray desorption electrospray ionization mass spectrometry (nano-DESI
MS), and ion chromatography (IC). A large number of oxygenated molecules are
identified, including oligomers containing up to six monomer units,
functionalized monomer and oligomers with carbonyl, carboxyl, and hydroxyl
groups, and small organic acid anions (e.g., formate, acetate, oxalate, and
malate). The average atomic oxygen-to-carbon (O / C) ratios of phenolic
aqSOA are in the range of 0.85–1.23, similar to those of low-volatility
oxygenated organic aerosol (LV-OOA) observed in ambient air. The aqSOA
compositions are overall similar for the same precursor, but the reactions
mediated by 3C* are faster than · OH-mediated reactions and
produce more oligomers and hydroxylated species at the point when 50% of
the phenolic compound has reacted. Profiles determined using a thermodenuder
indicate that the volatility of phenolic aqSOA is influenced by both oligomer
content and O / C ratio. In addition, the aqSOA shows enhanced light
absorption in the UV–visible region, suggesting that aqueous-phase reactions
of phenols may contribute to formation of secondary brown carbon in the
atmosphere, especially in regions influenced by biomass burning. |
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