CAREER: Visualizing Structures and Ultrafast Dynamics of Heterogeneous Interfaces Using Time-Resolved Electron Imaging

在这个由美国国家科学基金化学结构、动力学和机制A项目资助的项目中，休斯敦大学的杨丁舒教授和他的学生正在使用先进的电子显微镜和电子衍射技术来探索吸附在表面上的分子的结构和运动。这项研究可能对我们对各种表面过程的理解产生重要影响，例如催化反应和润滑剂的作用。该研究项目还为研究生提供了最先进的光谱学和显微镜方面的培训，并为休斯顿地区的高中生提供了教育和推广。该教育计划的独特之处在于，在当地教育工作者和学生访问休斯敦大学校园后，他将继续与他们进行对话，并通过倡导和扩大化学奥林匹克竞赛的参与来促进化学教育。总的来说，这个项目的推广和教育工作是必要的，因为休斯敦大学在德克萨斯州休斯顿发挥着重要的教育和经济作用，为代表性不足的群体提供了机会。该项目利用时间分辨扫描电子显微镜（TR-SEM）和两种电子衍射技术-反射高能电子衍射（RHEED）和超快电子衍射(UED) -表征表面光诱导物理化学过程的电子和结构动力学，以及界面薄膜相变动力学。所采用的实验工具允许在平衡和光激发条件下研究表面化学系统和分子组装。目标体系包括水、醇和高度有序的火石石墨（HOPG）、石墨烯、单晶硅、砷化镓和铜上的离子液体，其比较研究包括不同强度或亲和力的不同分子间和界面相互作用。

In this project funded by the Chemical Structure, Dynamics and Mechanisms A program of the National Science Foundation, Professor Ding-Shyue Yang of the University of Houston (UH) and his students are using advanced electron microscopy and electron diffraction techniques to explore the structure and motions of molecules adsorbed onto surfaces. The research may have important impacts on our understanding of a variety of surface processes, such as catalytic reactions and the action of lubricants. The research project is also providing a vehicle for the training of graduate students in state-of-the-art spectroscopy and microscopy, as well as education and outreach to high school students in the Houston area.The unique thrust of the educational plan is the continuing dialogue with local educators and students following their UH campus visits and his promotion of chemical education through advocating and expanding the participation in Chemistry Olympiad competitions. Overall, the outreach and educational efforts in this project are needed, as UH plays a critical educational and economic role in Houston, TX, providing opportunities to underrepresented groups.The proposed project utilizes time-resolved scanning electron microscopy (TR-SEM) and two electron diffraction techniques - reflection high-energy electron diffraction (RHEED) and ultrafast electron diffraction (UED) - to characterize the electronic and structural dynamics of photo-induced physicochemical processes at surfaces, and the dynamics of phase transitions of interfacial thin films. The experimental tools employed allow for the study of surface chemical systems and molecular assemblies under both equilibrium and photo-excited conditions. The target systems include water, alcohol and ionic liquid species on highly-ordered pyrolitic graphite (HOPG), graphene, single crystal silicon, gallium arsenide and copper, whose comparative studies encompass different intermolecular and interfacial interactions with varied strength or affinity.