Organic compounds trapped inside and on surfaces of atmospheric particles are readily accessible to actinic radiation from the sun. While the gas-phase photochemistry of organic compounds is relatively well understood, the rates and mechanisms of photochemical transformations of organic compounds in particles are poorly known. Recently, the role of photosensitized reactions in aerosol chemistry, where a photosensitizer absorbs light at a given wavelength causes an increase in aerosol mass and diameter, has been discussed in the literature. This presentation will describe our experiments that characterize the photosensitization reactions of secondary organic aerosols (SOA) containing photosensitizers in the condensed-phase and in the presence of various volatile organic compounds (VOCs). We generate a suite of model SOA by oxidation of VOCs in a smog chamber, collect SOA on an inert substrate, irradiate them with near-UV and/or visible radiation in the presence of a selected VOC, and examine the suppression of photoproduced VOCs in the gas phase by proton transfer reaction mass spectrometry. Special attention is given to the uptake of a given VOC and the increase in condensed-phase mass.

Irradiation of secondary organic aerosol material in the presence of volatile organic compounds: The role of photosensitization

253rd National Meeting (2017)

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