X-ray Absorption Spectroscopy

Brookhaven Laboratory

Mount Holyoke students who are part of Darby Dyar's research program may have an opportunity to contribute to work with x-ray absorption spectroscopy (XAS), either at Argonne National laboratory or Brookhaven National Laboratory. For more than two decades, students have assisted with measurements there and undertaken research projects leading to publications and senior thesis work.

The 13-ID-E X-ray microprobe beamline at the Advanced Photon Source (Argonne National Laboratory) is part of the University of Chicago’s GeoSoilEnviroCARS sector.

  • This insertion device beamline at sector 13 provides full-time availability of the microprobe to the user community. The 13-ID-E X-ray beam is focused using 240 mm long silicon mirrors in a Kirkpatrick-Baez geometry, which provide a focused beam size for microspectroscopy of ~ 1×2 m (sub-micrometer focus in the vertical is possible). 
  • The mirrors and upstream flight path at the upstream end of the experimental station sit within helium filled enclosures to minimize X-ray absorption. Multiple mirror coatings on both the focusing mirrors and an upstream set of mirrors that provide monochromatic beam deflection (including bare Si, Rh and Pt) ensure optimal harmonic rejection. 
  • The beamline undulator X-ray source (a new 3.6 cm period device) and monochromator are designed to provide X-ray spectroscopy capabilities in the energy range from 2.3 keV (sulfur K-edge) to 28 keV with a photon flux of ~ 1011 photons/sec in a micrometer-sized spot. This operating energy range will provide access to K absorption edges of all the elements discussed as part of this proposal. 
  • The 13-ID-E monochromator system incorporates both Si(111) and Si(311). X-ray fluorescence from the sample is measured using a Vortex ME4 (Hitachi) silicon drift diode (SDD) detector array.

The Submicron Resolution X-ray Spectroscopy (SRX) beamline at the National Synchrotron Light Source II (Brookhaven National Laboratory) shares a low-β straight section with two canted in-vacuum undulators with the X-ray Fluorescence Nanoprobe (XFN).

  • Each beamline is optimized to reach very high spatial resolution for a specific energy range. SRX is optimized to access higher energy and is included in the initial scope of NSLS-II. It will access an energy range from E = 4.65 keV to E = 25 keV. 
  • Two sets of Kirkpatrick-Baez (KB) mirror optics will focus the beam creating either a sub-micrometer sized focal spot at high flux or a sub-100 nm spot at moderate flux. A swap between the two setups will be possible in a couple of minutes. 
  • The wide energy range covered by SRX will allow the scientific community to address a wide range of research topics, as absorption edges of a large number of elements can be reached. This will enable scientists to use elemental mapping as well as spectroscopy for their studies. 
  • Available techniques at the beamline include: X-ray absorption imaging, X-ray fluorescence imaging, X-ray tomography, X-ray fluorescence trace element mapping, XAS absorption spectroscopy, XAS fluorescence spectroscopy, X-ray spectro-microscopy, and X-ray micro-diffraction.