Theoretical and Experimental Investigations of Photoheterolysis Reactions

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With this award, the Chemical Structure Dynamics and Mechanisms-B Program supports the research of Professor Arthur Winter at Iowa State University. Professor Winter seeks to understand the structure-reactivity principles for photochemical reactions, with the long-term goal of developing a predictive theoretical model that relates chemical structure to reactivity. The research focuses on why certain types of structures break apart to form ions. The research uses a combination of theory and experiment. Photochemical reactions have broad applications in biology and environmental chemistry. Establishing the basic mechanisms for fundamental bond breaking contributes to the broader challenge of understanding the guiding principles in photochemical reactions. Professor Winter engages college freshman in an early multidisciplinary research experiences through the Freshman Research Initiative. This research provides research opportunities for undergraduates and students from under-represented groups. To study photoheterolysis reactions, Professor Winter uses a joint theoretical/experimental approach. High-level computational methods are used to map excited state transition states and surface crossing topologies in selected reactions which are known to proceed by heterolysis. Ultrafast femtosecond-resolved transient absorption spectroscopy is used to determine the rates and mechanisms of photoheterolysis reactions on model substrates, while high-level excited state calculations are designed to provide a mechanistic rationale. This combination of theory and experiment determines the effect of structure on the rates and mechanisms of photorelease in model systems. The Professor Winter leads a Freshman Research Initiative at ISU that engages freshmen in an early multidisciplinary research program. He also continues his Chats with Eminent Female Scientists (ChEFS) Initiative, involving online video interviews with successful academics, providing insights and advice for students interested in an academic career.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.