Mapping Atomic Motions with Ultrabright Electrons: Fundamental Space-Time Limits to Imaging Chemistry

PI正从德国马克斯普朗克研究所（他是联合创始人）转回多伦多大学。所申请的资金将使该研究项目得以继续，重点是原子解析动力学。这个研究项目是一项为期10年的努力的一部分，旨在应对科学领域的一些重大挑战，特别是在基本时空限制下直接成像化学和生物学。这个项目利用了PI团队开发的超亮电子源技术，可以实时点亮原子运动。主要的挑战是将这种成像技术推向单分子极限，在原子水平上观察单分子轨迹。这一目标现在已经实现。******本研究项目实现了部分化学梦境实验：1)获得了第一个结构跃迁的分子电影，2)第一个具有保守立体化学（键形成）的完全原子分辨的电环化电影，3)有机和有机金属体系中的电子转移，4)经典的I3问题和晶格在指导化学中的作用，5)第一个完全原子分辨的化学反应（通过解决图像重建中的相问题），实现了时空成像化学的基本极限。在对化学领域的影响方面，第一部原子电影说明了导致分子结构变化的大量可能的核运动，也称为化学，坍缩为几个关键的反应模式。正是这种发生在屏障穿越区域的维数的巨大减少，使得化学具有可转移性（即：命名反应的经验发现）。这项工作为基于反应模式的化学提供了一个新的概念基础，它将结构和动力学结合起来，有助于更好地预测势垒穿越区域的核构型，从而更好地控制化学。反应模式的概念（降维）被发现在复杂程度上缩放到生物分子的水平。随着电子源、探测器和纳米流体装置的最新进展，PI的小组正在接近获得单分子轨迹的原子分辨率，生物分子的原子实空间成像在行动中。本计划的最终目标是将这些研究中揭示的分子结构-功能关系连接起来，以关闭化学与生物学之间的循环。**

The PI is transitioning back from the Max Planck Institute in Germany (he co-founded) to the University of Toronto. The requested funds will enable continuation of this research program with a focus on atomically resolved dynamics. This research program is part of a 10-year effort to meet some of the grand challenges in science, notably to directly image chemistry and biology at fundamental space-time limits. This program exploits the ultrabright electron source technology developed by the PI's group to literally light up atomic motions in real time. The major challenge is to push this imaging technology to the single molecule limit to observe single molecule trajectories at the atomic level. This objective is now in reach.******This research program has achieved some of the dream experiments in chemistry: 1) obtaining the first molecular movies of structural transitions, 2) first full atomically resolved movie of electrocyclization with conserved stereochemistry (bond formation), 3) electron transfer in organic and organometallic systems, 4) the classic I3 problem and effect of the lattice in directing chemistry, 5) and the first full atomic resolved chemical reaction (via solving the phase problem in image reconstruction), which achieved the fundamental limits in space-time imaging chemistry. In terms of impact on the field of chemistry, the very first atomic movies illustrated that the numerous number of possible nuclear motions leading to changes in molecular structure, also known as chemistry, collapse to just a few key reaction modes. It is this enormous reduction in dimensionality that occurs in the barrier crossing region that makes chemistry transferable (re: the empirical discovery of named reactions). This work has led to a new conceptual basis for chemistry based on reaction modes that unifies structure and dynamics to help better predict the nuclear configurations of the barrier crossing region and thereby better control chemistry. The concept of reaction modes (reduced dimensionality) is found to scale in complexity to the level of biological molecules. With recent advances in electron sources, detectors, and nanofluidic devices, the PI's group is closing in on obtaining atomic resolution to single molecular trajectories atomic real space imaging of bio-molecules in action. The ultimate objective of this program is to connect molecular structure-function relationships revealed in these studies to close the loop between chemistry and biology. **