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| Titel |
Heterogeneous OH oxidation of palmitic acid in single component and internally mixed aerosol particles: vaporization and the role of particle phase |
| VerfasserIn |
V. F. McNeill, R. L. N. Yatavelli, J. A. Thornton, C. B. Stipe, O. Landgrebe |
| 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 ; 8, no. 17 ; Nr. 8, no. 17 (2008-09-12), S.5465-5476 |
| Datensatznummer |
250006376
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| Publikation (Nr.) |
 copernicus.org/acp-8-5465-2008.pdf |
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| Zusammenfassung |
| We studied the OH oxidation of submicron aerosol particles consisting of
pure palmitic acid (PA) or thin (near monolayer) coatings of PA on aqueous
and effloresced inorganic salt particles. Experiments were performed as a
function of particle size and OH exposure using a continuous-flow
photochemical reaction chamber coupled to a chemical ionization mass
spectrometer (CIMS) system, for detection of gas and particle-bound
organics, and a DMA/CPC for monitoring particle size distributions. The loss
rate of PA observed for pure PA aerosols and PA on crystalline NaCl aerosols
indicates that the OH oxidation of PA at the gas-aerosol interface is
efficient. The pure PA oxidation data are well represented by a model
consisting of four main processes: 1) surface-only reactions between OH and
palmitic acid, 2) secondary reactions between palmitic acid and OH oxidation
products, 3) volatilization of condensed-phase mass, and 4) a surface
renewal process. Using this model we infer a value of γOH
between 0.8 and 1. The oxidation of palmitic acid in thin film coatings of
salt particles is also efficient, though the inferred γOH is
lower, ranging from ~0.3+0.1/−0.05) for coatings on solid NaCl and
~0.05 (±0.01) on aqueous NaCl particles. These results,
together with simultaneous data on particle size change and volatilized
oxidation products, provide support for the ideas that oxidative aging of
aliphatic organic aerosol is a source of small oxidized volatile organic
compounds (OVOCs), and that OH oxidation may initiate secondary
condensed-phase reactions. |
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