SURFACE AND INTERFACE SCIENCE AT CHESS.

X-rays are useful for probing structure at buried surfaces including gas/solid, liquid/solid, solid/solid, or gas/liquid interfaces because they can penetrate easily through layers of low-density matter before reaching a surface. The high-intensity x-radiation from a synchrotron is especially good because the scattering signals from surface layers are inherently weak in comparison with signals from the bulk. An excellent facility is the unique Cornell High Energy Synchrotron Source (CHESS), which can supply and adapt the radiation to meet specific experimental requirements. This article discusses a technique called extened x-ray absorption fine structure (EXAFS) spectroscopy which is used in different current studies at CHESS. It is based on photoionization, a process that plays a major role in attenuating a penetrating x-ray beam. The main topics are studying the interface at an electrode surface, x-ray standing waves to study surfaces, and the atomic structure of grain boundaries.