Photochemistry at Organic Particle-Air Interfaces

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The research performed under this project will investigate the mechanisms underlying photochemical processes that occur on the air-solid interfaces of particles in the atmosphere; specifically, those governing the ultraviolet photolysis of organic films that have been partially oxidized by ozone and/or the hydroxyl radical. The principal technique to be used is infrared "cavity ring-down spectroscopy" to detect gas-phase products evolved from the irradiated surfaces. A secondary goal is to study the ozonolysis of unsaturated organics. The results of this research will be applicable to aerosol particles which play a pivotal role in the Earth's atmosphere, from providing a unique heterogeneous environment for chemical reactions to serving as condensation nuclei for cloud formation and efficiently scattering solar radiation. Because aerosol particles are continuously exposed to solar radiation during the daytime, they can potentially serve as media or, in special cases, as catalysts for photochemical processes in the atmosphere.This research will be useful for establishing rational environmental standards for particulate matter in the lower atmosphere, and for improving the predictive power of air pollution and global climate models. Understanding photochemical properties of aerosol particles will help to better predict their atmospheric fates and environmental impacts, and ultimately reduce the risk of population exposure to especially harmful aerosols. This work includes creating a course on air pollution for freshman students, and using the investigator's laboratory instrumentation for training graduate and undergraduate students, providing hands-on training for high school science teachers, and presenting educational seminars to the general public.