MINERAL SURFACE AND INTERFACIAL SCIENCE AT GSECARS

The GeoSoilEnviroCARS beamlines, located at the Advanced Photon Source (APS) and operated by the University of Chicago, provide members of the Earth and environmental science community with the tools and training required to take advantage of numerous synchrotron-based analytical techniques. From its inception, the GSECARS surface and interfacial science program has focused on molecular-scale determination of crystal termination structure, interaction with water, adsorbate conformation, and reactivity. Recent developments include new tools that will dramatically expand the suite of molecular-level mineral-fluid interfacial structures and solution conditions that can be probed by synchrotron x-ray techniques such as crystal truncation rod (CTR) diffraction and resonant anomalous x-ray reflectivity (RAXR). Historically, mineral-fluid interface scattering experiments have been limited to highly idealized systems encompassing a short list of minerals that grow to form large, perfect single crystals. Chemical conditions for three-dimensional atomic structural measurements have traditionally been limited to systems at chemical equilibrium and solutions that are stable in films a few microns thick. By developing new sample environments, measurement technologies, and data analysis tools the program is opening the techniques to an unprecedented range of mineralogy and chemical complexity, enabling rapid resolution of pressing scientific problems by a wide community of scientists. Following the APS Upgrade (APS-U), enhanced X-ray optics coupled with the exceptional new source will enable novel measurement capabilities not previously possible.