Vapor鈥揥all Deposition in Chambers: Theoretical Considerations

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• 作者：Renee C. McVay ; Christopher D. Cappa ; John H. Seinfeld
• 刊名：Environmental Science & Technology
• 出版年：2014
• 出版时间：September 2, 2014
• 年：2014
• 卷：48
• 期：17
• 页码：10251-10258
• 全文大小：367K
• ISSN：1520-5851

文摘

In order to constrain the effects of vapor鈥搘all 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鈥損article dynamics model, we examine the extent to which this increase is the result of vapor鈥搘all 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鈥搘all deposition, and gas鈥損article equilibration. The gas鈥損article equilibration time scale depends on the gas鈥損article accommodation coefficient 伪_p. Regardless of the extent of kinetic limitation, vapor鈥搘all 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鈥搘all deposition and kinetic limitations must be taken into account.