Articles | Volume 16, issue 3
Research article
03 Feb 2016
Research article |  | 03 Feb 2016

Constraining condensed-phase formation kinetics of secondary organic aerosol components from isoprene epoxydiols

T. P. Riedel, Y.-H. Lin, Z. Zhang, K. Chu, J. A. Thornton, W. Vizuete, A. Gold, and J. D. Surratt

Abstract. Isomeric epoxydiols from isoprene photooxidation (IEPOX) have been shown to produce substantial amounts of secondary organic aerosol (SOA) mass and are therefore considered a major isoprene-derived SOA precursor. Heterogeneous reactions of IEPOX on atmospheric aerosols form various aerosol-phase components or "tracers" that contribute to the SOA mass burden. A limited number of the reaction rate constants for these acid-catalyzed aqueous-phase tracer formation reactions have been constrained through bulk laboratory measurements. We have designed a chemical box model with multiple experimental constraints to explicitly simulate gas- and aqueous-phase reactions during chamber experiments of SOA growth from IEPOX uptake onto acidic sulfate aerosol. The model is constrained by measurements of the IEPOX reactive uptake coefficient, IEPOX and aerosol chamber wall losses, chamber-measured aerosol mass and surface area concentrations, aerosol thermodynamic model calculations, and offline filter-based measurements of SOA tracers. By requiring the model output to match the SOA growth and offline filter measurements collected during the chamber experiments, we derive estimates of the tracer formation reaction rate constants that have not yet been measured or estimated for bulk solutions.

Short summary
IEPOX, a photooxidation product of isoprene, contributes to ambient secondary organic aerosol concentrations. Controlled atmospheric chamber experiments and modeling are used to extract formation rate information of chemical species that contribute to IEPOX-derived secondary organic aerosol.
Final-revised paper