CAREER: Photo-induced Ultrafast Electron-nuclear Dynamics in Molecules

职业：分子中光致超快电子核动力学

• 批准号: 2340570
• 负责人: Li Fang
• 金额: $ 81.4万
• 依托单位: The University of Central Florida Board of Trustees
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2024
• 资助国家: 美国
• 起止时间: 2024-05-01 至 2029-04-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2340570&HistoricalAwards=false
• 关键词: CAREER; Photo; induced; Ultrafast; Electron

General audience abstract: When a molecule is subject to a sudden disturbance, such as the removal of one or more electrons, the remaining electrons and atomic nuclei move. In many cases, one can assume that the light electrons adapt themselves instantly to the positions of the much heavier atomic nuclei as the molecule changes shape (the “Born-Oppenheimer approximation”), but this is only approximately true. The electrons, which exhibit both wave and particle aspects, can interfere with each other. The resulting electron wavepackets can oscillate rapidly compared to the motion of the atomic nuclei. Such “electron coherences” are thought to be important in chemical and biological processes such as vision but have been difficult to study due to the extremely short timescales on which they evolve (a few attoseconds, where one attosecond = 0.000000000000000001 seconds). This extremely fast electron motion will be affected by the comparatively slower motion of the atomic nuclei. The PI and her research team will use state-of-the-art lasers and photon sources on the campus of the University of Central Florida to study the evolution of these electron coherences and their coupling to the underlying nuclear motions. Ultimately such studies may advance our ability to engineer reaction products and optimize energy harvesting. This CAREER award supports undergraduate and graduate students and postdoctoral researchers who will be trained in the use of state-of-the-art laser systems and associated advanced spectroscopic techniques. In addition, the award supports an educational and outreach project which includes a summer program focusing on instrumentation training for students, an introductory video sequence on ultrafast science addressing a broader audience, and events for high-school teachers and students, called “Go Ultrafast!”Technical audience abstract: When coherent light interacts with a molecule, multiple electronic states can be populated with specific relative phases, resulting in electronic coherences. In this project, the evolution of these electronic coherences will be time-resolved in a pump-probe scheme with temporal resolutions at the natural time scales of the electron and ion motion. The effect of electron-nuclear coupling on the electronic-coherence properties, such as their lengths, strengths, and revivals, will be investigated. Femtosecond infrared/near-infrared lasers and attosecond XUV/x-ray table-top light sources will be used as the pump or the probe. Electronic coherences will be monitored through electron kinetic energy and abundance variations as a function of the pump-probe delay, using electron-ion spectroscopy of 3-dimensional momentum imaging and transient absorption spectroscopy. Simultaneous measurement of electrons and ions in the momentum space will be used to show the correlation between the evolution of electron dynamics and ion motion. This project will advance our understanding of charge dynamics and photoenergy transformation and transfer mechanisms in molecules and pave a path to photocontrol schemes for directing energy flows. The results will provide reliable references for validation of theoretical methods in the non-Born-Oppenheimer regime.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.

普通受众摘要：当一个分子遭受突然灾难时，例如去除一个或多个电子，其余电子和原子核移动。在许多情况下，人们可以假设光电子立即适应自原子核的位置，因为分子变化（“ born-oppenheimer近似”），但这仅是属实的。揭示波浪和粒子方面的电子可以彼此干扰。 与原子核的运动相比，所得的电子波袋可以迅速振荡。 这种“电子相干”被认为在化学和生物学过程（例如视觉）中很重要，但由于它们发展的时间非常短，因此很难研究（其中一些attoseconds，其中一个= 0.00000000000000000001秒）。 这种极快的电子运动将受原子核运动相对较慢的影响。 PI和她的研究团队将在佛罗里达州中部校园内使用最先进的激光器和光子来源，以研究这些电子相干的演变及其与基础核运动的耦合。最终，这样的研究可能会提高我们设计反应产品并优化能量收获的能力。该职业奖支持本科生和研究生和博士后研究人员，他们将接受最先进的激光系统和相关的高级光谱技术的培训。此外，该奖项还支持一个教育和外展项目，其中包括一项夏季计划，该计划着重于学生的仪器培训，关于超法科学的介绍视频序列，涉及更广泛的受众群体，以及为高中老师和学生提供的活动，称为“ Go Go Ultrafast！”技术摘要：当相干的光线与分子相互作用时，多个电子状态可以与特定的相对相对的相关性相互作用。在这个项目中，这些电子相干的演变将以泵探针方案的时间分辨，并在电子和离子运动的自然时间尺度下进行临时分辨率。电子 - 核耦合对电子碳的长度，强度和复兴等电子碳的影响。飞秒红外/近红外激光器和Attosend Xuv/X-ray台式光源将用作泵或探针。电子相干将通过电子动能和抽象变化来监测泵探针延迟的函数，使用3维动量成像和瞬时吸收光谱的电子离子光谱法。动量空间中电子和离子的同时测量将用于显示电子动力学和离子运动的演变之间的相关性。该项目将提高我们对分子中电荷动力学和光启动转化和转移机制的理解，并为指导能量流的光控制方案铺平道路。结果将为非出生的人类制度验证理论方法提供可靠的参考。该奖项反映了NSF的法定任务，并使用基金会的知识分子优点和更广泛的影响评估审查标准，被认为是通过评估来获得的支持。