Ultrafast streak camera system 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，并产生完美定时的飞秒电子探针脉冲。所要求的用于超快条纹相机的射频元件和激光系统将使使用单个长电子脉冲（几皮秒）在一次拍摄中对光激发后的整个时变结构信息进行编码成为可能，即一次拍摄完整的分子电影。时间分辨率将在10fs域，这是足够的，并且随着信噪比的急剧增加，将有可能直接观察电子分布随激发速度比核运动快而变化的影响。这种观察提供了电子密度梯度或力，负责将大量可能的核排列和波动坍缩到几个关键的反应模式。我们有机会将电子自由度和核自由度分开，从而全面理解导致不同类型反应机制广义性质的维数大幅降低的机制。所要求的仪器有望揭示使化学能够在生物系统中扩展复杂性的物理学，并使化学成为可转移的概念。所要求的仪器对于进入这个时空分辨率的新领域是必不可少的，同样重要的是要达到灵敏度，以观察化学的本质。值得注意的是，在成功地在德国汉堡共同建立了新的马克斯普朗克研究所和汉堡大学的超快成像中心之后，PI已于2020年转移回多伦多大学。他从2010年到2020年借调到马克斯普朗克，是基于上述研究计划的研究伙伴关系的一部分。由于马克斯·普朗克关于保留内部使用设备的政策，PI在汉堡开发的实验室中不可能移动所需的激光设备。如果没有所需的设备，就没有希望推进PI的计划来实现直接成像化学基本驱动力的宏伟目标。

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 photo injection using femtosecond lasers for both triggering the chemistry of interest and in generating perfectly timed femtosecond electron probe pulses. The requested rf components and laser system for the ultrafast streak camera will make it possible to employ a single long electron pulse (a few picoseconds) to encode the entire time-varying structural information after photoexcitation in a single shot, i.e., single shot full molecular movies. The time resolution will be in the 10 fs domain, which is sufficient and along with the dramatic increase in signal to noise ratio will make it possible to directly observe the effect of changes in electron distribution with excitation faster than nuclear motions. This observation provides the electron density gradients or forces responsible for collapsing the enormous number of possible nuclear permutations and fluctuations to just a few key reaction modes. We have the opportunity to separate the electronic and nuclear degrees of freedom to come to a full understanding of the mechanism leading to the enormous reduction in dimensionality responsible for the generalized properties for the different classes of reaction mechanisms. The requested instrumentation holds the promise to reveal the physics that has enabled chemistry to scale in complexity all the way to biological systems and makes chemistry a transferrable concept. The requested instrumentation is essential to enter this new domain in space-time resolution, and equally important to achieve sensitivity, for observing the very essence of chemistry. It should be noted that the PI has transitioned back to the University of Toronto in 2020 after successfully co-founding a new Max Planck Institute in Hamburg Germany and the Centre for Ultrafast Imaging for the University of Hamburg. His secondment to the Max Planck from 2010 to 2020 was part of a research partnership based on the above research program. It was not possible to move the needed laser equipment in the labs the PI developed in Hamburg due to Max Planck policies on retaining equipment for internal use. Without the requested equipment, there is no prospect for advancing the PI's program to realize this grand objective to directly imaging the fundamental driving forces for chemistry.