Atomic-Scale View of Interfacial Processes with X-rays Our research program includes the development of novel X-ray probes and the characterization of surface, interface, and thin-film structures with atomic resolution. We conduct our experiments using both in-house and synchrotron X-ray facilities. The latter have greatly enhanced chemical and structural sensitivity for studying systems as dilute as one-hundredth of an atomic monolayer.

XSW image of Zn2+ ions at the rutile (110) -aqueous interface.

In addition to using more conventional X-ray scattering and spectroscopy techniques, we have developed a number of methods for generating X-ray standing waves with differing characteristic length scales. We use these periodic X-ray probes to pinpoint the lattice location of adsorbate atoms on crystalline surfaces, to measure strain within epitaxially grown semiconductor and ferroelectric thin films, and to locate heavy atoms within ordered ultrathin organic films.

Using a state-of-the-art surface science facility at the Advanced Photon Source, we perform in situ analysis of surface structures and phase transformations of MBE-grown ordered atomic monolayers on semiconductor and complex oxide surfaces. We also use X-ray standing waves, high-resolution X-ray diffraction, and X-ray absorption spectroscopy for structural characterization of buried strained-layer semiconductor heterostructures, ferroelectric thin films and the water/crystalline interface.

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