CAREER: State-Specific Characterization of Intermolecular Vibronic Mixing Between Dipyrrolic Pigment Subunits

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With support from the Chemical Structure, Dynamics, and Mechanisms-A (CSDM-A) Program in the Division of Chemistry, Jacob Dean of Southern Utah University will investigate how specific molecular vibrations, stimulated from visible and UV light absorption, influence the transfer of electronic energy between molecules such as those relevant in light harvesting in biological and engineered systems. Currently, understanding how key vibrations in the light absorbing components of these systems shuttle energy is limited by the complexity of systems and fast time scales at which energy dissipates. Dr. Dean and his group will use advanced laser and time-resolved spectroscopies to measure these vibrational motions in molecules. Undergraduate students, including those from traditionally underrepresented groups, will be trained in this research and in advanced physical chemistry research efforts.Laser spectroscopy coupled with jet cooling will be used to enable mode- and quantum state-resolved interrogation of intermolecular vibronic coupling and vibrationally-mediated energy transfer in dipyrrolic subunits derived from native photosynthetic pigments and small dipyrrole aggregates in the gas phase. Femtosecond coherence spectroscopy of dipyrrole aggregates in solution at room temperature will subsequently be used to assess the robustness of the resulting vibronic mixing models developed. Better understanding of electronic-vibrational (vibronic) coupling between molecules has the potential to reveal how energy is transferred within molecular aggregates. Through improved structure-vibration-function elucidation, Dr. Dean and his group aim to extend this knowledge to energy transport in biological and engineered light-harvesting molecules and materials. In so doing, the experimental articulation of a rich parameter space involving both the rapid and directional understanding of energy transfer that entangles quantized vibrations with pigment electronic states to optimize the aggregate’s energy landscape is envisioned.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.