Photoactivator Chemistry in Atmospheric Aerosols

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With this award, the Environmental Chemical Sciences Program of the Division of Chemistry is funding Professor Faye McNeill of Columbia University who, in collaboration with Professors Hai-Lung Dai and Yi Rao of Temple University is investigating photochemical reactions related to atmospheric aerosols. Sunlight is the primary driving force in gas-phase atmospheric chemistry, but the importance of photochemistry occurring inside atmospheric aerosol particles or at the gas-aerosol interface is not well understood. Reactions involving the participation of light-absorbing organic aerosol components as photo-activators have been suggested as pathways for the photochemical origin and processing of important gas-phase species such as NO2 (nitrogen dioxide) and O3 (ozone). This project uses a combination of theory and experiment to investigate chemistry inside aerosols. The PIs have also developed an integrated education and outreach program consisting of three major thrusts: (1) AIRE, a Spanish/English bilingual blog and informational website targeted at students and educators (2) Research and curriculum development with local K-12 science educators, and (3) a teacher certification program designed to train midcareer and early retiree mathematics and science professionals as middle-school teachersThe proposed research is inspired by the hypothesis that photoactivated chemistry involving light-absorbing organic compounds inside atmospheric aerosol particles may lead to the formation of oxidized aerosol organic material, either via the direct oxidation of volatile organic compounds (VOCs) or via the formation of oxidizing radicals in the aerosol phase. This hypothesis is being tested her by a combination of experimental and modeling approaches designed to gain the necessary molecular-level insight into photoactivated aerosol chemistry. Advanced spectroscopic techniques, laser flash photolysis, and computational chemistry will be used to create new knowledge of the systems of interest at the molecular level. Aerosol flow reactor experiments are to be used to quantify the kinetics of these processes under aerosol conditions. The impact of this chemistry in the environmental context is to be evaluated via atmospheric chemistry modeling. This work is expected to provide insight into atmospheric aerosol chemistry with broader scientific impact on the impact of emitted gases upon air composition and derivative properties.