Ultrafast Dynamics of Electronic Excited States: Photocatalysis and Photomagnetism

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In this project funded by the Chemical Structure, Dynamics, and Mechanisms Program-A (CSDM-A) and the Chemical Instrumentation Program of Division of Chemistry, Professor Kevin J. Kubarych of the University of Michigan and his graduate and undergraduate students are addressing the fundamental relationships between structure, dynamics and function in molecules that, powered by light, are poised to dramatically reshape approaches to transforming carbon dioxide and to storing information. In both classes of system, photocatalysts for reduction of carbon dioxide, and photomagnets, the key chemical starting point involves molecules that have absorbed light, carrying out their initial functional steps in excited electronic states. Using novel experimental techniques based on ultrafast two-dimensional infrared (2D-IR) spectroscopy and related methods, Professor Kubarych and his group will obtain the level of detailed dynamical information on the active excited states that is presently only possible on ground state molecules. By employing novel pulse sequences that combine different spectral ranges such as the visible and infrared, including multiple laser sources permitting access to timescales ranging from femtoseconds to seconds, Professor Kubarych's team will be able to disentangle complex photocycles and identify transient intermediate species using the powerful resolution of 2D-IR spectroscopy. With the addition of low-temperature capabilities, the group will gain access to the cooperative ultrafast dynamics of photoswitchable magnetic molecules and materials, which they will examine using novel hybrid electronic/vibrational spectroscopy methods. The long term goal of this research project is to address the clear societal need to develop new approaches for energy conversion, storage, as well as the removal of greenhouse gases. Results of this project will guide development of new chemical systems as well as macromolecular constructs by elucidating the fundamental design principles. Professor Kubarych will leverage the widespread interest in energy, technology, and climate change to appeal to the next generation of women and minority scientists by developing hands-on demonstrations of dye-sensitized solar cells for middle and high school students in the southeast Michigan area. To dramatically broaden his reach, he will produce videos and a web resource describing basic challenges in solar energy conversion, highlighting the role of physical chemistry in the development of new solutions.