A new statistical model of secondary organic aerosol (SOA) formation has been developed that explicitly takes into account multi-generational oxidation as well as fragmentation of gas-phase compounds. The model framework requires three tunable parameters to describe the kinetic evolution of SOA mass, the average oxygen-to-carbon atomic ratio and the mean particle volatility as oxidation proceeds. These parameters describe (1) the relationship between oxygen content and volatility, (2) the probability of fragmentation and (3) the amount of oxygen added per reaction. The time-evolution and absolute value of the SOA mass depends sensitively on all three tunable parameters. Of the tunable parameters, the mean O:C is most sensitive to the oxygen/volatility relationship, exhibiting only a weak dependence on the other two. The mean particle O:C produced from a given compound is primarily controlled by the number of carbon atoms comprising the SOA precursor. This model provides a generalized framework for the interpretation of laboratory SOA formation experiments in which explicit consideration of multiple-generations of products is required, which is true for all photo-oxidation experiments. Application of this model to a variety of SOA precursors as well as general concepts for broader-scale use of the model will be discussed.

Multigeneration gas-phase oxidation, equilibrium partitioning, and the formation and evolution of secondary organic aerosol

244th National Meeting (2012)

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