Quantum Dynamical Studies of Time-resolved Nonlinear Optical Signals from Spatially Oriented Electronic Energy Transfer Complexes

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Jeffrey A. Cina of the University of Oregon is supported by an award from the Chemical Theory, Models and Computational Methods program in the Division of Chemistry for the theoretical study of molecular energy-transfer processes of relevance to the natural and artificial harvesting of solar energy. His research group will develop and implement methods to efficiently simulate quantum mechanical aspects of electronic energy transfer in realistic molecular networks comprising several light-absorbing units and to predict and interpret the results of useful and revealing ultrafast-laser measurements on these important and widely studied systems. Cina will serve scientific outreach by organizing a seminar-style undergraduate course for non-science majors on the science of climate change. He will continue to foster improved inclusivity in the scientific community by exercising and modeling welcoming, supportive actions in his research and teaching roles.In collaboration with his graduate-student co-workers, Jeffrey Cina will carry out theoretical investigations of a new measurement strategies that will apply existing tools of multi-dimensional electronic spectroscopy (also known as multi-dimensional wave-packet interferometry, or WPI) to spatially oriented ensembles of electronic excitation energy transfer dimers, trimers, or tetramers (or to individual small multimers). He will predict and interpret ultrafast spectroscopy signals containing direct, isolable information on the time-course of intersite or interexciton electronic coherence—key determinants of the nature and efficiency of excitation transport. He will carry out simulations of measurable signals of this kind on model systems of increasing degrees of complexity and realism. In support of this objective, he will develop, test, and apply a new protocol that treats discrete site-excited or excitonic states as a quantum mechanical subsystem while modeling the dynamics of intramolecular, chromophore-medium, and medium nuclear degrees of freedom with compactly parametrized, semiclassical trial wave packets. In addition, Cina will explore the effects of quantum mechanical "which-path" interference of electronic excitation transport in few-chromophore complexes, and identify spectroscopic signatures of this specific coherence-dependent phenomenon.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.