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Environ Sci Technol

Title:		Vapor-wall deposition in chambers: theoretical considerations
Author(s):		McVay RC; Cappa CD; Seinfeld JH;
Address:		"Division of Chemistry and Chemical Engineering and section signDivision of Engineering and Applied Science, California Institute of Technology , Pasadena, California 91125, United States"
Journal Title:		Environ Sci Technol
Year:		2014
Volume:		20140813
Issue:		17
Page Number:		10251 - 10258
DOI:		10.1021/es502170j
ISSN/ISBN:		1520-5851 (Electronic) 0013-936X (Linking)
Abstract:		"In order to constrain the effects of vapor-wall deposition on measured secondary organic aerosol (SOA) yields in laboratory chambers, researchers recently varied the seed aerosol surface area in toluene oxidation and observed a clear increase in the SOA yield with increasing seed surface area (Zhang, X.; et al. Proc. Natl. Acad. Sci. U.S.A. 2014, 111, 5802). Using a coupled vapor-particle dynamics model, we examine the extent to which this increase is the result of vapor-wall deposition versus kinetic limitations arising from imperfect accommodation of organic species into the particle phase. We show that a seed surface area dependence of the SOA yield is present only when condensation of vapors onto particles is kinetically limited. The existence of kinetic limitation can be predicted by comparing the characteristic time scales of gas-phase reaction, vapor-wall deposition, and gas-particle equilibration. The gas-particle equilibration time scale depends on the gas-particle accommodation coefficient alphap. Regardless of the extent of kinetic limitation, vapor-wall deposition depresses the SOA yield from that in its absence since vapor molecules that might otherwise condense on particles deposit on the walls. To accurately extrapolate chamber-derived yields to atmospheric conditions, both vapor-wall deposition and kinetic limitations must be taken into account"
Keywords:		"Aerosols/*analysis Computer Simulation Gases/chemistry *Models, Theoretical Time Factors Volatile Organic Compounds/analysis Volatilization;"
Notes:		"MedlineMcVay, Renee C Cappa, Christopher D Seinfeld, John H eng Research Support, Non-U.S. Gov't 2014/08/15 Environ Sci Technol. 2014 Sep 2; 48(17):10251-8. doi: 10.1021/es502170j. Epub 2014 Aug 13"