Collaborative Research: Surface-specific Aerosol Chemistry: Direct Observations, Kinetics, and Environmental Impact

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The Environmental Chemical Sciences Program of the Division of Chemistry supports this project by Professors V. Faye McNeill at Columbia University and Yi Rao at Utah State University. The project addresses how surfaces of atmospheric particles uniquely affect the chemical reactions taking place there. A better understanding of atmospheric particle chemistry is needed for quantifying the impacts of human activities on air quality and climate. Until recently, this understanding was limited by a lack of analytical techniques capable of probing surface-specific particle chemistry. The team has developed unique laboratory methods for studying the chemistry of particles suspended in gas in a laboratory setting. These are surface-specific sum frequency generation (SFG) and highly-sensitive HyperRaman Scattering (HRS). These techniques will be applied together with complementary gas-particle chemical kinetics studies to characterize processes that are unique to aerosol surfaces. In addition to the training of graduate and undergraduate students at both institutions, the team will also engage in outreach activities designed to reach students from underrepresented groups in science and engineering, and the general public.Surface-specific particle chemistry will be investigated in three scenarios: (1) the acid-catalyzed oligomerization of acetaldehyde at the gas-aerosol interface, (2) the formation of light-absorbing products from the reactions of methoxyphenols in aqueous aerosols, and their subsequent liquid-liquid phase separation, and (3) small particles which are expected to have a sharp pressure gradient between the surface and bulk, with implications for aqueous reaction rates (Laplace pressure). The team will also conduct numerical simulations in order to evaluate the potential environmental impact of these processes and develop representations for this new chemistry in large-scale atmospheric models.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.