The Center for Chemistry at the Space-Time Limit (CaSTL)

时空极限化学中心（Center for Chemistry at the Space-Time Limit，简称CASTL）致力于开发新的科学，可用于观察和记录原子和化学键水平上的分子运动。这套新工具，统称为化学镜，将通过可视化分子内原子振动、形成新键或催化化学反应时的运动来揭示新的见解。研究人员正在特别关注太阳能转化为化学形式的能量的过程的细节，希望能在真实的时间内捕捉到这一关键的能量转化事件。这项工作正在产生更广泛的影响，因为它开发了新的技术，以非常精细的尺度显示化学事件，并通过各种公共媒体传播其结果。这项工作正在通过发明新的科学工具来促进创新，这些工具正在走向商业发展。 除了直接促进参与中心研究的学生的教育发展外，CASTL还组织和参与各种正式和非正式的科学教育活动，针对不同教育背景的受众。例如，针对更广泛的化学社区的暑期学校，针对高中生的加州数学和科学暑期学校（COSMOS），以及各种非正式的科学教育活动，如男孩和女孩俱乐部的课后计划。在此资助期间，CaSTL将继续开发全光学版本的工作化学镜，沿着的版本，结合联合收割机光学扫描探针显微镜，并最终观察分子运动和转换的飞秒埃时空尺度。该小组正在将这一工具应用于特定的化学问题，特别是等离子体增强的化学问题。集体电子的激发，热电子的形成，它们在界面上的热化和散射，电子或空穴注入催化分子中心以及随后的键的断裂和形成都是时空捕获的目标。通过对催化金属簇和异质结构的时间分辨光电子发射显微镜（tr-PEEM）和双光子光电子发射（tr-2 PP），他们正在努力充分表征等离子体激元激发时金属侧引发的时空动力学。完整的时间过程中的光催化的分子转化的表面侧是可能的，使用时空分辨的表面增强非线性相干光谱。理论研究被用来指导这个独特的工具集的能力的开发和完善。作为该中心工作的结果，设想对光物理和化学的完整理解，从催化中涉及的小分子到设备的工程介观结构。

The Center for Chemistry at the Space-Time Limit (CaSTL) focuses on the development of novel science that can be used to observe and record motions of molecules at the atomic and chemical bond level. This set of new tools, collectively known as the chemiscope, will reveal new insights by visualizing the motions of atoms within molecules as they vibrate, form new bonds or catalyze chemical reactions. The investigators are paying special attention to the details of the process by which solar energy is converted to chemical forms of energy, hoping to catch this crucial energy conversion event in the act, in real time. The work is having a broader impact through the development of new technologies for visualizing chemical events on a very fine scale, and also through the dissemination of their results in a variety of public media. The work is furthering innovation through the invention of new scientific tools that are being moved toward commercial development. In addition to directly contributing to the educational development of students involved in the center's research, CaSTL organizes and participates in a variety of formal and informal science education activities, targeting audiences with varying educational backgrounds. Examples include summer schools for the broader chemistry community, the California State Summer School for Math and Science (COSMOS) aimed at high school students, and a variety of informal science education activities, such as an afterschool program at the Boys and Girls Club.During this funding period, CaSTL will continue development of an all-optical version of a working chemiscope, along with versions that combine optics with scan probe microscopes, and the ultimate observation of molecular motions and transformations on a femtosecond-Angstrom spatiotemporal scale. The group is moving toward application of this tool to specific chemical problems, in particular plasmon-enhanced photocatalysis. The excitation of collective electrons, the formation of hot electrons, their thermalization and scattering on interfaces, injection of electrons or holes into catalytic molecular centers and the subsequent breaking and making of bonds are targeted for capturing in space-time. Through time-resolved photoelectron emission microscopy (tr-PEEM) and 2-photon photoemission (tr-2PP) on catalytic metal clusters and hetero-structures, they are working to fully characterize the space-time dynamics initiated on the metal side upon excitation of plasmons. The complete time course of the photocatalyzed molecular transformation on the surface side is made possible using space-time-resolved surface-enhanced nonlinear coherent spectroscopy. Theoretical investigations are being used to guide the development and refinement of capabilities of this unique toolset. A complete understanding of photo-physics and chemistry ranging from small molecules implicated in catalysis to engineered mesoscale structures for devices is envisioned as a result of the center's work.