Microscale X-ray Absorption Spectroscopy on the GSECARS Sector 13 at the APS

GeoSoilEnviroCARS (GSECARS) is a national user facility for frontier research in the earth sciences using synchrotrons radiation at the Advanced Photon Source, Argonne National Laboratory. GSECARS provides earth scientists with access to the high-brilliance hard x-rays from this third-generation synchrotrons light source. The research conducted at this facility will advance our knowledge of the composition, structure and properties of earth materials, the processes they control and the processes that produce them. All principal synchrotron-based analytical techniques in demand by earth scientists are being brought to bear on earth science problems: (1) high-pressure/high-temperature crystallography and spectroscopy using the diamond anvil cell; (2) high-pressure/high-temperature crystallography using the large-volume press; (3) powder, single crystal and interface diffraction; (4) x-ray absorption fine structure (XAFS) spectroscopy; (5) x-ray fluorescence microprobe analysis and microspectroscopy; and (6) microtomography. This grant supported the design and construction of dedicated microspectroscopy instrumentation (x-ray absorption fine structure (XAFS) spectroscopy techniques, e.g., EXAFS and XANES, applied with approx micrometer spatial resolution) as part of the GeoSoilEnviroCARS national user facility. This new APS instrumentation offers dramatically improved capabilities over existing facilities in terms of spatial resolution and elemental sensitivity. MicroXAFS is essential in cases where sample size is limited (such as fluid inclusions in minerals, fine-grained minerals and samples in diamond anvil, high pressure cells) and/or chemical speciation is heterogeneous (fine-grained, polymineralic sediments and rocks, zoned crystals, and products of non-equilibrium reactions). The new instrumentation is applicable to studies of hydrothermal fluid processes, migration and encapsulation of toxic and radioactive wastes, for example...