McVay, Renee C. and Cappa, Christopher D. and Seinfeld, John H. (2014) Vapor−Wall Deposition in Chambers: Theoretical Considerations. Environmental Science and Technology, 48 (17). pp. 10251-10258. ISSN 0013-936X. http://resolver.caltech.edu/CaltechAUTHORS:20140820-083412204
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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 α_p. 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.
|Additional Information:||© 2014 American Chemical Society. Received: May 02, 2014. Accepted: August 05, 2014. Revised: August 04, 2014. Publication Date (Web): August 13, 2014. We thank Jeffrey Pierce for providing the APE model, which served as a framework for the present model, and Sally Ng and Joseph Ensberg for useful input. R.C.M. acknowledges support by a National Science Foundation Graduate Research Fellowship under Grant No. DGE-1144469. This work was supported by the Office of Science (BER), U.S. Department of Energy, Grant No. DE-SC0006626; NOAA Climate Program Office’s AC4 program, Award No. NA13OAR4310058; and the State of California Air Resources Board, Contract 12-312.|
|Official Citation:||Vapor–Wall Deposition in Chambers: Theoretical Considerations Renee C. McVay, Christopher D. Cappa, and John H. Seinfeld Environmental Science & Technology 2014 48 (17), 10251-10258|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Ruth Sustaita|
|Deposited On:||20 Aug 2014 15:56|
|Last Modified:||26 Sep 2014 20:01|
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