Andrew Lambe, Senior Research Scientist, Aerodyne Research Inc.
Characterization of secondary organic aerosol (SOA) remains challenging due to inherent molecular complexity and physical/chemical properties that change over the course of atmospheric oxidative aging. In addition, standard laboratory SOA generation and measurement techniques have limitations that often result in incomplete or indirect characterization of the SOA. Our current work involves development and application of the Potential Aerosol Mass (PAM) oxidation flow reactor technique for generating SOA from the oxidation of (1) known precursors in targeted laboratory studies and (2) unknown precursors present in ambient air in field studies by hydroxyl radicals, nitrate radicals, and halogen atoms. Measurement techniques used to characterize particle chemical, physical and optical properties over simulated photochemical aging timescales ranging from approximately 1 to 10 days are discussed. Our goals are to identify correlations between associated chemical, physical, and optical properties that may help explain field measurements and enable more accurate chemistry and climate models.