Micro-beam X-ray absorption and fluorescence spectroscopies at GSECARS: APS beamline 131D

GeoSoilEnviroCARS, sector 13 of the Advanced Photon Source at Argonne National Laboratory, provides a micro-beam facility for XAFS, XANES, XRF, and x-ray diffraction studies. A Kirkpatrick-Baez mirror pair gives a focussed monochromatic undulator beam down to 1 x 1 mu m with sufficient intensity for x-ray fluorescence mapping and extended XAFS of dilute systems at energies above 4KeV. Special emphasis for these facilities has been given to environmental and earth science studies, including dilute contaminants in natural sediments. As an example, XRF maps and EXAFS data taken with a 4 mu m by 7 mu m spot size are shown for the Pu L-III edge of a natural tuff exposed to a dilute aqueous solution of Pu. In addition, x-ray diffraction and scattering capabilities allow the study of surfaces and surface adsorbates with micron-sized beams using xray reflectivity, x-ray standing-waves, and grazing-incidence XAFS.