Atmospheric organic aerosol (OA) is known to undergo rapid oxidation ('aging'), involving changes to particle mass and oxidation state, over timescales of several hours. However, the phases and mechanisms by which aging occurs are poorly understood, with laboratory studies generally unable to reproduce this rapid aging. We aim to determine the relative efficiency of aging in various phases through an examination of the partitioning and rates of oxidation. Oxidation can take place in the gas, condensed organic, or liquid-water phase. The oxidation rate in each case is a function of the rate coefficient, oxidant concentration, and fraction of the reactant present in that phase, which is controlled by the reactant's saturation vapor pressure, Henry's law constant, and the mass concentrations of solvent. Here, the contributions of these quantities to the oxidation rate of model organics are examined, in an effort to better understand the phase in which OA aging occurs.

Role of multiphase aging in the chemistry of organic aerosol

244th National Meeting (2012)

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