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

University Of Houston, Houston TX

Investigators

Abstract

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.