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Role of ozone in SOA formation from alkane photooxidation

Zhang, X. and Schwantes, R. H. and Coggon, M. M. and Loza, C. L. and Schilling, K. A. and Flagan, R. C. and Seinfeld, J. H. (2014) Role of ozone in SOA formation from alkane photooxidation. Atmospheric Chemistry and Physics, 14 (3). pp. 1733-1753. ISSN 1680-7316. https://resolver.caltech.edu/CaltechAUTHORS:20140407-135255247

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Abstract

Long-chain alkanes, which can be categorized as intermediate volatility organic compounds, are an important source of secondary organic aerosol (SOA). Mechanisms for the gas-phase OH-initiated oxidation of long-chain alkanes have been well documented; particle-phase chemistry, however, has received less attention. The δ-hydroxycarbonyl, which is generated from the isomerization of alkoxy radicals, can undergo heterogeneous cyclization and dehydration to form substituted dihydrofuran. Due to the presence of C=C bonds, the substituted dihydrofuran is predicted to be highly reactive with OH, and even more so with O_3 and NO_3, thereby opening a reaction pathway that is not usually accessible to alkanes. This work focuses on the role of substituted dihydrofuran formation and its subsequent reaction with OH, and more importantly ozone, in SOA formation from the photooxidation of long-chain alkanes. Experiments were carried out in the Caltech Environmental Chamber using dodecane as a representative alkane to investigate the difference in aerosol composition generated from "OH-oxidation-dominating" vs. "ozonolysis-dominating" environments. A detailed mechanism incorporating the specific gas-phase photochemistry, together with the heterogeneous formation of substituted dihydrofuran and its subsequent gas-phase OH/O_3 oxidation, is used to evaluate the importance of this reaction channel in dodecane SOA formation. We conclude that (1) the formation of δ-hydroxycarbonyl and its subsequent heterogeneous conversion to substituted dihydrofuran is significant in the presence of NO_x; (2) the ozonolysis of substituted dihydrofuran dominates over the OH-initiated oxidation under conditions prevalent in urban and rural air; and (3) a spectrum of highly oxygenated products with carboxylic acid, ester, and ether functional groups are produced from the substituted dihydrofuran chemistry, thereby affecting the average oxidation state of the SOA.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.5194/acp-14-1733-2014 DOIArticle
http://www.atmos-chem-phys.net/14/1733/2014/acp-14-1733-2014.htmlPublisherArticle
ORCID:
AuthorORCID
Schwantes, R. H.0000-0002-7095-3718
Coggon, M. M.0000-0002-5763-1925
Flagan, R. C.0000-0001-5690-770X
Seinfeld, J. H.0000-0003-1344-4068
Additional Information:© 2014 Author(s). This work is distributed under the Creative Commons Attribution 3.0 License. Published by Copernicus Publications on behalf of the European Geosciences Union. Received: 15 August 2013. Published in Atmos. Chem. Phys. Discuss.: 24 September 2013. Revised: 2 January 2014. Accepted: 9 January 2014. Published: 14 February 2014. This work was supported by National Science Foundation grant AGS-1057183. Edited by: A. Laskin.
Funders:
Funding AgencyGrant Number
NSFAGS-1057183
Issue or Number:3
Record Number:CaltechAUTHORS:20140407-135255247
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20140407-135255247
Official Citation:Zhang, X., Schwantes, R. H., Coggon, M. M., Loza, C. L., Schilling, K. A., Flagan, R. C., and Seinfeld, J. H.: Role of ozone in SOA formation from alkane photooxidation, Atmos. Chem. Phys., 14, 1733-1753, doi:10.5194/acp-14-1733-2014, 2014.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:44711
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:07 Apr 2014 21:22
Last Modified:03 Oct 2019 06:21

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