NSLS-II Seminar

Knowledge of atomic arrangements and composition at surfaces in complex environments and at buried interfaces is fundamental to our understanding and control of fabricated thin-film structures and of complex interfaces found in nature. Indeed, many critical processes are controlled by interfacial structure and chemistry. Because of favorable cross sections, x-rays offer a unique opportunity to penetrate through gas, liquid, or solid thin-films to probe this structure on the atomic length scale. The hard x-ray brilliance of the Advanced Photon Source (APS) enables these in-situ studies and permits real-time investigations. In this talk, I will illustrate several important x-ray scattering and imaging techniques that are presently used at the APS for the study of interface structure. One area includes materials synthesis where in-situ, time-resolved crystal truncation rod scattering has been used to demonstrate that Pulsed Laser Deposition (PLD) is a two-layer growth process, largely governed by extremely fast non-equilibrium interlayer transport. In other studies, new x-ray imaging techniques have been used to characterize surface and buried interface structures with excellent spatial resolution. For example, X-ray Reflection Imaging Microscopy (XRIM) is a promising new full-field imaging technique that exploits phase contrast in interface scattering and has been used at the APS to characterize the step/terrace structure at solid-solid and solid-fluid interfaces. In addition to an overview of these current research capabilities, plans to expand Interface Science research at the APS through development of a dedicated, comprehensive facility will also be presented.