The Role of Peroxy Radicals: Linking Gas-Phase Oxidation Chemistry to Secondary Organic Aerosol Formation

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This work focuses on improving the fundamental understanding of processes that contribute to the formation of secondary organic aerosol (SOA - very small particles formed from gas-phase compounds) in the atmosphere. A series of laboratory chamber experiments is being conducted to evaluate the atmospheric conditions and concentrations of various chemical species that lead to SOA formation. The results of this research will lead to improved models for predicting SOA formation.The objectives of this research are: (1) To experimentally map out the effects of the different reaction channels of peroxy radicals on SOA yields, gas- and aerosol-phase composition from photochemical oxidations of biogenic and anthropogenic hydrocarbons, and (2) To determine the effects of different peroxy radical reaction pathways on aerosol volatility. The proposed work focuses on oxidation by OH radicals under dry conditions (relative humidity 1%). Ammonium sulfate is being used as seeds for aerosol growth and hydrogen peroxide (H2O2), nitrous acid (HONO), or methyl nitrite (CH3ONO) is being used as the OH source. This research will also help improve understanding of how nitrogen oxides influence the SOA formation process.The project includes outreach plans at the Columbia Middle School (a Title 1 school) to work with an Earth Science teacher and middle school students to increase their knowledge and experience in science, technology, engineering, and math (STEM) disciplines.