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

在这项由化学结构、动力学和机理资助的项目中，休斯顿大学的杨丁雪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的分子的结构和运动。这项研究可能会对我们理解各种表面过程，如催化反应和润滑剂的作用产生重要影响。该研究项目还为研究生提供了一种在最先进的光谱学和显微镜方面的培训工具，以及对休斯顿地区的高中生的教育和推广。教育计划的独特之处在于，在UH校园参观后与当地教育工作者和学生继续对话，并通过倡导和扩大参加化学奥林匹克竞赛来促进化学教育。总体而言，由于UH在德克萨斯州休斯敦扮演着关键的教育和经济角色，为未被充分代表的群体提供机会，因此该项目的推广和教育工作是必要的。拟议的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)-来表征表面光诱导物理化学过程的电子和结构动力学，以及界面薄膜的相变动力学。所使用的实验工具允许在平衡和光激发条件下研究表面化学体系和分子组装。目标体系包括水、醇和高度有序的热解石墨(HOPG)、石墨烯、单晶硅、砷化镓和铜上的离子液体物种，它们的比较研究涵盖了不同强度或亲和力的不同分子和界面相互作用。

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.