Femtosecond Laser for Mapping Atomic Motions with Ultrabright Electrons

PI的团队已经实现了成像化学的基本时空限制，并发现了导致过渡态区域维数降低的基本物理学，这使得化学成为一个可转移的概念。这个长久以来梦寐以求的化学实验是通过开发超亮电子源实现的，这种电子源能够实时点亮原子运动。这种超亮电子源依赖于使用飞秒激光器的光注入来触发感兴趣的化学反应，并产生具有足够电子的完美定时飞秒电子探针脉冲，以实现单次结构测定。在这方面，所要求的飞秒激光系统对于PI的研究计划的继续至关重要。它是仪器的核心，构成了一个真正的分子电影摄像机，用于捕捉原子水平上的化学细节。

The PI's group has achieved the fundamental space-time limit to imaging chemistry and has unearthed the basic physics that leads to the reduction in dimensionality in the transition state region that makes chemistry a transferable concept. This long held dream experiment in chemistry was achieved through the development of ultrabright electron sources capable of literally lighting up atomic motions in real time. This ultrabright electron source depends on the use of photoinjection using femtosecond lasers for both triggering the chemistry of interest and in generating perfectly timed femtosecond electron probe pulses with sufficient electrons to enable single shot structure determination. In this respect, the requested femtosecond laser system is essential for continuation of the PI's research program. It is the heart of the instrumentation that constitutes a veritable molecular movie camera for capturing chemistry in action at the atomic level of detail. In this regard, the primary focus of the proposed research will be on the development of a reaction mode basis as a new conceptual framework for understanding chemistry. Our ability to control barriers to desired chemical processes is still largely empirical. Chemistry is dynamic. We need a dynamic basis for categorizing chemistry and looking for trends. With the development of the “Molecular Movie Camera” by the PI's group, we can now directly observe the far-from-equilibrium atomic motions involved in chemistry with better than 0.01 on 100 fs timescales, i.e. at the fundamental space-time limit to imaging chemistry. To date, we have observed for all systems from classic 3 atom systems to processes of larger and larger systems, all the way to systems as complex as proteins that the chemistry involved is largely propagated along the reaction coordinate by the displacement of a few key modes. This experimentally derived reaction mode basis, to guide theory, will unify structure and dynamics in conceptualizing chemistry. The next phase of the research will focus on developing samples specifically designed to probe different chemical reactions, from electron transfer, proton tautomeization, electrocyclization reactions, to bimolecular processes to answer this question. These studies, from small molecular systems to biological systems, will help understand the scaling of chemistry to higher levels of complexity that ultimately led to living matter. It should be noted that the PI has transitioned back to the University of Toronto after successfully co-founding a new Max Planck Institute in Hamburg Germany as part of a research partnership based on this research program. It was not possible to move the laser equipment in the labs the PI developed in Hamburg due to Max Planck policies on retaining equipment for internal use. Without the requested femtosecond laser, there is no prospect for continuation of this program at the current level.