Visualizing Molecular Dynamics in Large Molecules using Intense, femtosecond, Pump-Probe Laser Pulses

该研究计划将制作“分子电影”，用于研究激光在分子中诱导的基本物理和化学过程。这项研究的目的是确定光诱导转化在大分子中发生所需的时间。这一点很重要，因为光诱导的过程在我们的环境中持续发生，例如阳光照射在地球的大气层，植物叶片和人类皮肤上。这个团队将使用强大的桌面激光脉冲记录“分子电影”。一个脉冲将被用来启动分子价电子轨道的电离，然后第二个脉冲和离子检测系统将被用来捕获的转变的时间演化。将被研究的分子，包括乙醇和内嵌富勒烯，与工业相关，可以作为该团队开发的测量协议的测试件。 这个项目将制作的分子电影很重要，因为它们将揭示驱动这些分子发生特定反应的物理和化学过程。在这个项目中接受培训的学生和博士后将学习他们未来在学术界和工业界工作所需的技能。本研究计划将重点研究时间分辨的光诱导异构化的醇和内嵌富勒烯（M3N@C80）在长波长（IR）多光子电离和隧道制度的时间演化。后一个实验的目标是了解激发的超原子分子轨道（SAMO）状态在这两种不同能量状态中的作用。实验将使用台式激光泵浦-探测技术进行，产生的带电碎片将使用称为冷靶反冲离子动量光谱系统的电子-离子-离子符合监测器进行检测。因此，基本的动力学将揭示符合离子动量成像。这个团队对科学进步的贡献源于他们先进的探测方法，在真实的时间，在飞秒尺度，物理和化学过程。这是通过使用强飞秒台式激光器与双光学参量放大器，这将使双色泵浦探测实验，并将推动基本飞秒时间分辨大分子动力学研究的电流极限。这项工作将与理论家合作完成，这将使该团队能够定量地了解物理过程的复杂性，并在实验与理论不一致的情况下验证或推进计算/建模。

This research program will make "molecular movies" that will be used to study fundamental physical and chemical processes induced in molecules by laser light. The goal of this investigation is to determine the time it takes for light-induced transformations to occur in large molecules. This is important because light-induced processes occur continuously in our environment, for example from sunlight shining on earth's atmosphere, plant leaves, and human skin. This team will record "molecular movies" by using strong table-top laser pulses. One pulse will be used to initiate the ionization of the molecular valence electrons orbitals, and then a second pulse and an ion detection system will be used to capture the time-evolution of the transformation. The molecules that will be studied, including ethanol and endohedral fullerenes, are relevant for industries and can serve as test-pieces for the measurement protocols developed by this team. The molecular movies that this project will produce are important because they will reveal physical and chemical processes that drive specific reactions with these molecules. Students and postdocs that get trained on this project learn skills that they will use for future jobs in academia and industry. This research program will focus on investigating the time-resolved photo-induced isomerization of alcohol and the time evolution of endohedral fullerenes (M3N@C80) in the long-wavelength (IR) multiphoton ionization and the tunneling regimes. The goal for the latter experiment is to understand the role of excited super atomic molecular orbital (SAMO) states in these two different energy regimes. The experiments will be carried out using table-top laser pump-probe technique and the resulting charged fragments will be detected using an electron-ion-ion coincidence monitor known as a Cold-Target Recoil Ion Momentum Spectroscopy (COLTRIMS) system. The underlying dynamics will thus be revealed by coincident ion-momentum imaging. This team's contribution to advance science stems from their advanced approach to probe, in real time, and at the femtosecond scale, physical and chemical processes. This is achieved by using intense femtosecond table-top laser with twin optical parametric amplifiers which will enable 2-color pump-probe experiments and will push the current limit of fundamental femtosecond time-resolved large molecular dynamics investigations. This work will be done in partnership with theorists, which will allow this team to understand quantitatively the complexity of the physical processes and which will validate or push forward the calculations/modeling in cases of disagreements between experiment and theory.