CAREER: Investigating Ultrafast Electronic and Structural Dynamics During Light-Driven Chemical Reactions

该项目将开发新的实验工具，用于成像分子中光化学反应过程中的超快动力学。这将使对光诱导反应的新研究成为可能，这些研究在几个科学领域都很重要。例如，光化学解离反应在大气化学中起着重要的作用。光诱导的分子开环和异构化反应也是理解维生素D的生物合成、控制有机分子开关的动力学和设计新型捕光材料的原型。因此，在电子水平上对这种反应进行成像和控制可以导致新技术的发展，对社会具有潜在的好处。该项目将吸引来自不同背景的学生，并通过在他们的学术生涯早期向他们介绍科学研究来培养他们对基础科学和技术学科的兴趣。学生将从各种研究环境中受益，从大学最先进的激光实验室到国家实验室操作的大规模用户设施。为了进一步了解光驱动反应中发生的超快电子和结构动力学，该项目将使用飞秒光源，并结合强大的探测技术，如符合电子和离子动量成像和时间分辨光电子光谱。这些工具将用于研究与化学相关的有机分子的异构化和开环反应。以实验室为基础的飞秒激光和高次谐源的飞秒泵浦探测技术将得到自由电子激光实验的补充。能够记录基准光化学反应的“分子电影”将允许更直接地与量子化学计算进行比较。其目的是为了更好地了解潜在的反应机制，并开发和优化控制此类反应的动力学和结果的方案。该项目由物理部的原子、分子和光学物理实验计划和化学部的化学测量和成像计划(这两个部门都在NSF数学和物理科学局)以及促进竞争性研究的既定计划共同资助。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。

This project will develop new experimental tools for imaging ultrafast dynamics during photochemical reactions in molecules. This will enable new studies of light-induced reactions that are important in several scientific areas. For example, photochemical dissociation reactions play a major role in atmospheric chemistry. Light-induced molecular ring-opening and isomerization reactions also serve as prototypes for understanding biosynthesis of vitamin D, controlling the dynamics of organic molecular switches, and engineering novel light-harvesting materials. Imaging and controlling such reactions at the electronic level can therefore lead to the development of new technologies with potential benefits to society. This project will engage students from diverse backgrounds and foster their interest in basic science and technology disciplines by introducing them early in their academic career to scientific research. Students will benefit from a variety of research environments ranging from a state-of-the-art laser laboratory at a university to large-scale user facilities operated at national laboratories.To further the understanding of the ultrafast electronic and structural dynamics occurring during light-driven reactions, this project will use femtosecond light sources combined with powerful detection techniques such as coincident electron and ion momentum imaging and time-resolved photoelectron spectroscopy. These tools will be used to study isomerization and ring-opening reactions in organic molecules with chemical relevance. Femtosecond pump-probe techniques with laboratory-based femtosecond lasers and high-order harmonic generation sources will be complemented by experiments with free-electron lasers. Being able to record "molecular movies" of benchmark photochemical reactions will allow for a more direct comparison to quantum chemistry calculations. The aim is to provide a better understanding of the underlying reaction mechanism and to develop and optimize schemes for controlling the dynamics and outcome of such reactions.This project is jointly funded by the Atomic, Molecular, and Optical Physics Experiment program in the Division of Physics and the Chemical Measurement and Imaging program in the Division of Chemistry (both Divisions are in the NSF Directorate for Mathematical and Physical Sciences) as well as the Established Program to Stimulate Competitive Research.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.