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Vapor wall deposition in Teflon chambers

Zhang, X. and Schwantes, R. H. and McVay, R. C. and Lignell, H. and Coggon, M. M. and Flagan, R. C. and Seinfeld, J. H. (2015) Vapor wall deposition in Teflon chambers. Atmospheric Chemistry and Physics, 15 (8). pp. 4197-4214. ISSN 1680-7316. doi:10.5194/acp-15-4197-2015.

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Teflon chambers are ubiquitous in studies of atmospheric chemistry. Secondary organic aerosol (SOA) formation can be underestimated, owing to deposition of SOA-forming vapors to the chamber wall. We present here an experimental protocol and a model framework to constrain the vapor–wall interactions in Teflon chambers. We measured the wall deposition rates of 25 oxidized organic compounds generated from the photooxidation of isoprene, toluene, α-pinene, and dodecane in two chambers that had been extensively used and in two new unused chambers. We found that the extent of prior use of the chamber did not significantly affect the sorption behavior of the Teflon films. Among the 25 compounds studied, the maximum wall deposition rate is exhibited by the most highly oxygenated and least volatile compounds. By optimizing the model output to the observed vapor decay profiles, we identified that the dominant parameter governing the extent of wall deposition of a compound is its wall accommodation coefficient (α_(wi)), which can be correlated through its volatility with the number of carbons and oxygens in the molecule. By doing so, the wall-induced deposition rate of intermediate/semi-volatile organic vapors can be reasonably predicted based on their molecular constituency. The extent to which vapor wall deposition impacts measured SOA yields depends on the competition between uptake of organic vapors by suspended particles and the chamber wall. The timescale associated with vapor wall deposition can vary from minutes to hours depending on the value of α_(w,i). For volatile and intermediate volatility organic compounds (small α_(w,i)), gas-particle partitioning will dominate wall deposition for typical particle number concentrations in chamber experiments. For compounds characterized by relatively large α_(w,i), vapor transport to particles is suppressed by competition with the chamber wall even with perfect particle accommodation.

Item Type:Article
Related URLs:
URLURL TypeDescription DOIArticle
Schwantes, R. H.0000-0002-7095-3718
McVay, R. C.0000-0001-7766-5009
Lignell, H.0000-0001-7049-1659
Coggon, M. M.0000-0002-5763-1925
Flagan, R. C.0000-0001-5690-770X
Seinfeld, J. H.0000-0003-1344-4068
Additional Information:© Author(s) 2015. CC Attribution 3.0 License. Published by Copernicus Publications on behalf of the European Geosciences Union. Received: 23 September 2014 – Published in Atmos. Chem. Phys. Discuss.: 24 October 2014. Revised: 7 February 2015 – Accepted: 25 March 2015 – Published: 23 April 2015. This study was supported by NOAA Climate Program Office AC4 program, award # NA13OAR4310058 and State of California Air Resources Board agreement 13-321.
Funding AgencyGrant Number
National Oceanic and Atmospheric Administration (NOAA)A13OAR4310058
California Air Resources Board13-321
Issue or Number:8
Record Number:CaltechAUTHORS:20150603-080918173
Persistent URL:
Official Citation:Zhang, X., Schwantes, R. H., McVay, R. C., Lignell, H., Coggon, M. M., Flagan, R. C., and Seinfeld, J. H.: Vapor wall deposition in Teflon chambers, Atmos. Chem. Phys., 15, 4197-4214, doi:10.5194/acp-15-4197-2015, 2015
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:57963
Deposited By: Tony Diaz
Deposited On:03 Jun 2015 17:33
Last Modified:10 Nov 2021 21:57

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