Condensed-Phase Organic Photochemistry in Aerosol Particles and in Aerosol Liquid Water

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This project includes a number of laboratory experiments to study the fate of small particles exposed to sunlight in the atmosphere. Exposure to sunlight can cause chemical changes in the particles that reduces their atmospheric lifetimes. This research will provide valuable information for predicting the fate of aged organic particulate matter and is relevant to understanding the health effects of fine particles in the atmosphere.The objectives of this research are to: (1) systematically explore the dependence of secondary organic aerosol (SOA) photodegradation rates on the type of SOA and on the conditions of SOA formation; (2) investigate photochemistry of SOA in highly concentrated solutions of inorganic electrolytes mimicking the conditions found in aerosol liquid water; (3) investigate the relative importance of direct and indirect photochemical processes in irradiated SOA; and (4) investigate photodegradation and photosensitization processes in biomass-burning organic aerosols.The results of these experiments will be used to model the effects of photochemical reactions occurring inside atmospheric organic particles and inside cloud droplets containing dissolved organics on the global atmospheric burden of organic aerosol. This effort will directly support the training of at least two graduate students and at least six undergraduate students.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.