Time-Resolved, Electric-Field-Induced Vibrational Spectroscopy for Molecular Conformation Studies

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With support from the Chemical Measurement and Imaging and Chemical Structure, Dynamics and Mechanisms programs in the Division of Chemistry, Professors Xiong and Paesani at University of California, San Diego, are developing new methods for studying molecules and their behaviors at interfaces. The study is essential for optimizing performance of many chemical systems and devices. The team is using a combined experimental and theoretical approach to find a technical solution for some important societal needs, ranging from renewable energy to next generation flexible electronics and displays. This collaborative research project provides participating students with unique experiences at the interface of laser spectroscopy and computational chemistry, and thus promotes interdisciplinary research at University of California, San Diego. This project also provides opportunities for undergraduate students to gain hands-on research experience with cutting-edge technology through a summer research program and through other existing UCSD-based outreach programs. The proposed time-resolved electric-field-induced heterodyne sum frequency spectroscopy enables studies of interfacial charge transfer and delivers an in-depth understanding of hidden relationships between molecular physics and ultrafast charge transfer dynamics at complex interfaces. The multidimensional SFG is a recently developed spectroscopic technique that can resolve fine spectral signatures of various conformations on heterogeneous interfaces. Together with computer simulation, molecular conformation and spectral relationships are revealed. The time-resolved electric-field-induced effect enables following ultrafast charge transfer at interfaces through the modulation of SFG signals. By integrating time-resolved electric-filed-induce effect with the multidimensional SFG spectroscopy, molecular conformations that favor charge dynamics at complex interfaces are discovered. This new approach is used to study interfacial charge transfer between organic semiconductors and metal or inorganic semiconductors.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.