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| Titel |
Organic aerosol formation from the reactive uptake of isoprene epoxydiols (IEPOX) onto non-acidified inorganic seeds |
| VerfasserIn |
T. B. Nguyen, M. M. Coggon, K. H. Bates, X. Zhang, R. H. Schwantes, K. A. Schilling, C. L. Loza, R. C. Flagan, P. O. Wennberg, J. H. Seinfeld |
| 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. 7 ; Nr. 14, no. 7 (2014-04-08), S.3497-3510 |
| Datensatznummer |
250118570
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| Publikation (Nr.) |
 copernicus.org/acp-14-3497-2014.pdf |
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| Zusammenfassung |
| The reactive partitioning of cis and trans β-IEPOX
was investigated on hydrated inorganic seed particles, without the addition
of acids. No organic aerosol (OA) formation was observed on dry ammonium
sulfate (AS); however, prompt and efficient OA growth was observed for the
cis and trans β-IEPOX on AS seeds at liquid water
contents of 40–75% of the total particle mass. OA formation from IEPOX is
a kinetically limited process, thus the OA growth continues if there is a
reservoir of gas-phase IEPOX. There appears to be no differences, within
error, in the OA growth or composition attributable to the
cis / trans isomeric structures. Reactive uptake of IEPOX
onto hydrated AS seeds with added base (NaOH) also produced high OA loadings,
suggesting the pH dependence for OA formation from IEPOX is weak for AS
particles. No OA formation, after particle drying, was observed on seed
particles where Na+ was substituted for NH4+. The Henry's Law
partitioning of IEPOX was measured on NaCl particles (ionic strength
~9 M) to be 3 × 107 M atm−1 (−50 / +100%).
A small quantity of OA was produced when NH4+ was present in the
particles, but the chloride (Cl-) anion was substituted for sulfate
(SO42-), possibly suggesting differences in nucleophilic strength of
the anions. Online time-of-flight aerosol mass spectrometry and offline
filter analysis provide evidence of oxygenated hydrocarbons, organosulfates,
and amines in the particle organic composition. The results are consistent
with weak correlations between IEPOX-derived OA and particle acidity or
liquid water observed in field studies, as the chemical system is
nucleophile-limited and not limited in water or catalyst activity. |
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