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

在化学系化学结构、动力学和机制(CSDM-A)项目的支持下，南犹他大学的Jacob Dean将研究由可见光和紫外光吸收激发的特定分子振动如何影响分子之间的电子能量转移，例如与生物和工程系统中的光收集相关的分子。目前，了解这些系统的光吸收部件中的关键振动如何穿梭能量受到系统的复杂性和能量耗散的快速时标的限制。迪恩博士和他的团队将使用先进的激光和时间分辨光谱仪来测量分子中的这些振动运动。本科生，包括那些来自传统上代表不足的群体的学生，将在这项研究和高级物理化学研究工作中接受培训。激光光谱学与喷射冷却相结合将被用于实现分子间振动耦合和振动介导的能量传递的模式和量子态解析的询问，这些分子间的振动耦合和振动中介的能量转移来自天然光合色素和气相中的小联吡咯聚集体。随后将使用室温溶液中联吡咯聚集体的飞秒相干光谱来评估所建立的振动混合模型的稳健性。更好地理解分子之间的电子-振动(振动)耦合有可能揭示能量如何在分子聚集体中传递。通过改进结构-振动-功能阐明，迪恩博士和他的团队的目标是将这一知识扩展到生物和工程捕光分子和材料中的能量传输。在这样做的过程中，丰富的参数空间的实验表述被设想为包括快速和定向地理解能量转移，该能量转移将量子化的振动与颜料电子态纠缠在一起，以优化聚集体的能量格局。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

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.