CAREER: Elucidating the Interplay Between Exciton Dynamics and Symmetry-Breaking Charge Transfer Through Multidimensional Visible and Mid-Infrared Spectroscopies

职业：通过多维可见光和中红外光谱阐明激子动力学与对称破缺电荷转移之间的相互作用

• 批准号: 2047614
• 负责人: Jessica Anna
• 金额: $ 70万
• 依托单位: University of Pennsylvania
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-06-01 至 2026-05-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2047614&HistoricalAwards=false
• 关键词: CAREER; Elucidating; Interplay; Between; Exciton

With support from the Chemical Structure, Dynamics, and Mechanisms-A (CSDM-A) Program in the Division of Chemistry, Dr. Jessica Anna and her group at the University of Pennsylvania are investigating some of the earliest, and most important steps involved in the conversion of sunlight into energy. Solar energy conversion often begins with the transfer of energy or charge between two or more identical molecules that are packed together tightly. The close proximity and identical structures of the molecules make it very difficult to directly observe the first stages of the conversion process. In order to better understand these early events and how they affect solar energy conversion efficiency, Dr. Anna and her research team use sophisticated laser techniques to study pairs of molecules that represent more complicated systems. The team varies the relative distance and orientation of the two molecules in a well-defined way that allows them to distinguish changes caused by subtle differences in the way the two molecules interact with each other. The cutting-edge measurements they make provide new insight to aid in the design and development of new materials for solar energy conversion, including artificial photosynthetic complexes, photocatalysts, and organic photovoltaic materials. The project also involves educational and public outreach activities related to the research, including the development of new teaching modules for integration into graduate, undergraduate, and pre-college classrooms, as well as research opportunities and paid internships for undergraduates, pre-college students, and local area high school teachers. The teaching modules, research opportunities, and paid internships are designed to increase the participation of students in science, technology, engineering, and mathematics (STEM) fields, including underrepresented groups and first-generation college students. This project focuses on elucidating the interplay between exciton dynamics and charge transfer in a new family of pi-extended metallo-dipyrrin complexes. These systems have the potential to form excitonic states that undergo symmetry-breaking charge transfer, and therefore allow a systematic investigation of the interplay between energy- and charge-transfer processes. Dr. Anna and her students use pump-probe and coherent multidimensional spectroscopy in the visible and mid-IR spectral regions to study the different dipyrrin complexes and obtain a full characterization of the excited-state dynamics, structural rearrangement, and solvent reorganization involved in the symmetry-breaking charge transfer process. The research team uses a mixed spectral approach to probe the evolution of molecules in electronically excited states having charge-transfer character, harnessing the sensitivity of vibrational modes to the local electrostatic field. The team uses pump-probe spectroscopy to characterize population transfer and determine the branching ratios among different excited states in the dipyrrin complexes. The coherent multidimensional spectroscopy measurements provide more detailed information on the dynamics by alleviating spectral congestion, resolving vibrational modes in the excited state, and elucidating solvation dynamics and other relaxation processes. The comprehensive spectroscopic approach yields a deeper understanding of the combined role of intramolecular structural rearrangement and solvation dynamics in symmetry-breaking charge transfer processes that are important for solar energy conversion and other applications.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.

在化学结构，动力学和机制-A（CSDM-A）方案的支持下，杰西卡·安娜（Jessica Anna）博士及其宾夕法尼亚大学的小组正在研究一些最早，最重要的步骤阳光转化为能量。太阳能转化通常始于两个或更多相同的分子之间的能量或电荷的转移，这些分子被紧密地堆积在一起。分子的紧密近端和相同的结构使直接观察转换过程的第一阶段变得非常困难。为了更好地了解这些早期事件以及它们如何影响太阳能转化效率，Anna博士和她的研究团队使用复杂的激光技术来研究代表更复杂系统的分子。团队以明确的方式变化了两个分子的相对距离和方向，从而使他们能够区分两个分子相互作用的细微差异引起的变化。它们提供的尖端测量提供了新的见解，以帮助设计和开发太阳能转化的新材料，包括人工光合络合物，光催化剂和有机光伏材料。该项目还涉及与研究相关的教育和公共外展活动，包括开发新的教学模块，以整合到研究生，本科和大学前教室，以及研究机会以及为本科生，大学前学生，预科学生，大学生，付费实习和当地高中老师。教学模块，研究机会和付费实习旨在增加学生参与科学，技术，工程和数学（STEM）领域，包括代表性不足的群体和第一代大学生。 该项目的重点是阐明新的Pi-Exted Metallo-Dipyrrin络合物家族中激子动力学与电荷转移之间的相互作用。这些系统有可能形成经历对称性电荷转移的激子状态，因此可以系统地研究能量转移过程之间的相互作用。 Anna博士和她的学生使用可见和IR光谱区域中的泵探针和连贯的多维光谱研究来研究不同的二吡啶络合物复合物，并获得激发态动力学，结构重排和溶剂重组的全面表征破坏对称的电荷转移过程。研究团队使用一种混合光谱方法来探测具有电荷转移特征的电子激发态中分子的演变，从而利用了振动模式对局部静电场的敏感性。该团队使用泵探针光谱法来表征种群转移并确定二吡啶复合物中不同激发态之间的分支比率。连贯的多维光谱测量值通过减轻光谱充血，在激发态下解决振动模式以及阐明溶剂化动力学和其他松弛过程，从而提供了有关动力学的更详细信息。全面的光谱方法可以更深入地了解分子内结构重排和溶剂化动力在对称性的电荷传输过程中对太阳能转换和其他应用很重要的综合作用。这奖反映了NSF的法定任务，并被视为值得支持的支持。通过使用基金会的智力优点和更广泛影响的评论标准进行评估。