WDS poster XAFS11
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GeoSoilEnviroCARS The University of Chicago Matthew Newville, Stephen R. Sutton, and Mark L. Rivers Consortium for Advanced Radiation Sources, The Univeristy of Chicago, Chicago, IL 60637 The understanding of the chemical and physical state of Au in arsenopyrite ore deposits is complicated by the proximity of the Au L III and As K edges and their fluorescence lines. Shown below is the XRF spectra measured with the WDS. The tail of the As K line is comparable to the small Au L line even at the energy of the Au line. with Louis Cabri (NRC Canada), Robert Gordon, Daryl Crozier (Simon Fraser Univ) 1000ppm Au in arsenopyrite (FeAsS) Cs XRF Mapping with the WDS Using the WDS for EXAFS measurements: The Re L III -edge of K 7 [ReOP 2 W 17 O 61 ].nH 2 O with Mark Antonio (Argonne Natl Lab) The GSECARS Microprobe Station The table-top Kirkpatrick-Baez mirrors use a four-point bender and a trapezoidal mirror to dynamically shape a flat mirror into an ellipsis. They can focus a 300x300m monochromatic beam to down to 1x1m. With a working distance of 100m, they give a stable, energy-independent focal point and spot size, and are easy to use. Shown below is the microprobe station in 13-IDC, using Rh-coated silicon and fused- silica mirrors. The GeoSoilEnviroCARS undulator beamline (station 13-IDC at the APS) provides a micro-beam facility for x-ray fluorescence (XRF) and absorption (XAS) studies. The heart of the system is a Kirkpatrick-Baez focussing mirror, which can focus monochromatic undulator radiation down to 1x1 micron with enough intensity for XRF mapping and XAS of dilute systems. The microprobe has been successfully used for many problems in environmental and earth sciences. Kirkpatrick- Baez focusing mirrors table-top slits ion chamber sample positioner (x- y-z stage) optical microscope (10x to 50x) with video system fluorescence detector (WDS) The Wavelength Dispersive Spectrometer (Oxford WDX-600) This detector uses a Johansson geometry Rowland circle to analyze fluorescent x-rays. The sample, bent crystal analyzer, and detector slits all lie on a circle, with the angle between sample and detector and crystal lattice spacing selecting the accepted energy. LiF(200) and (220) crystals are typically used for hard x-ray energies. Tandem proportional counters (one sealed with 2atm Xe, and one using flowing P-10 gas) are the detectors. The energy resolution at 6KeV is ~10eV, and the detector will not saturate as solid-state detectors are prone to do. Though the solid-angle is small, the dynamic range and resolution make this detector an excellent complement to traditional solid-state fluorescence detectors. Examples of its use are shown throughout this poster. Here is a photograph and an x-ray fluorescence map of Cs (the L line) of a cross-cleavage plane of biotite exposed to a Cs-rich solution. This natural mica contains trace amounts of many transition metals including Ti, and large amounts of Ca and Fe, making a solid-state detector difficult to use for such a map. S Sutton, M Rivers, P Eng, M Newville, U. Chicago micro-XRF, XANES, and EXAFS Measurements with a Wavelength Dispersive Spectrometer Above is the XRF spectra for this W-rich sample measured with the WDS. Using a Ge or Si solid-state detector, the Re L line would be a shoulder on the W L line, the detector would tend to saturate from the unwanted W fluorescence, and the Re XAFS would essentially impossible to measure. The WDS allows us to isolate the Re L line and measure the XAFS of this previously “impossible” sample: XRF and XAFS measurements in many natural and heterogeneous samples are complicated by the prescence of fluorescence lines from other elements near the line of interest. A common problem is to measure a minor element (say, Re) in the prescence of a major element just below it in Z (say, W) whose fluorescence line will be excited at the absorption edge of the minor element. (dilute amounts of Co, Ni, or Zn in the prescence of Fe pose similar problems). Clockwise from lower left: measured (E), isolated EXAFS k(k), and the Fourier transform of the EXAFS |(R)|. Re L III -edge XAFS data for K 7 [ReOP 2 W 17 O 61 ].nH 2 O measured with the WDS. XRF Spectra of Au in FeAsS XAFS from a 13-element Ge detector 1000 x 200 m image of Cs fluorescence in biotite, made with a 5x5m beam, 5m steps, and 2sec dwell time per point (5hr collection time). The incident x- ray energy was 7.0KeV. On the left is the EXAFS spectra for 1000ppm Au in FeAsS measured with a 13- element Ge detector (at PNC-CAT: APS sector 20). On the right is the same sample (at two different spots) measured with the WDS. The WDS supresses the As K-edge, making the Au L III -edge much easier to see and analyze. The WDS spectra shows the Au to be heterogeneous -- sometimes metallic, and sometimes oxidized. with J McKinley, J Zachara, S Heald (PNNL) photograph of biotite cross- section Cs fluorescece map of biotite cross- section XAFS from the WDS
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Transcript of WDS poster XAFS11
GeoSoilEnviroCARS The University of ChicagoMatthew Newville, Stephen R. Sutton, and Mark L. RiversConsortium for Advanced Radiation Sources, The Univeristy of Chicago, Chicago, IL 60637
The understanding of the chemical and physical state of Au in arsenopyrite ore deposits is complicated by the proximity of the Au LIII and As K edges and their fluorescence lines. Shown below is the XRF spectra measured with the WDS. The tail of the As K line is comparable to the small Au L line even at the energy of the Au line.
with Louis Cabri (NRC Canada), Robert Gordon, Daryl Crozier (Simon Fraser Univ)
1000ppm Au in arsenopyrite (FeAsS)
Cs XRF Mapping with the WDS
Using the WDS for EXAFS measurements: The Re LIII-edge of K7[ReOP2W17O61].nH2O with Mark Antonio (Argonne Natl Lab)
The GSECARS Microprobe Station
The table-top Kirkpatrick-Baez mirrors use a four-point bender and a trapezoidal mirror to dynamically shape a flat mirror into an ellipsis. They can focus a 300x300m monochromatic beam to down to 1x1m. With a working distance of 100m, they give a stable, energy-independent focal point and spot size, and are easy to use.
Shown below is the microprobe station in 13-IDC, using Rh-coated silicon and fused-silica mirrors.
The GeoSoilEnviroCARS undulator beamline (station 13-IDC at the APS) provides a micro-beam facility for x-ray fluorescence (XRF) and absorption (XAS) studies. The heart of the system is a Kirkpatrick-Baez focussing mirror, which can focus monochromatic undulator radiation down to 1x1 micron with enough intensity for XRF mapping and XAS of dilute systems. The microprobe has been successfully used for many problems in environmental and earth sciences.
Kirkpatrick-Baez focusing mirrors
table-top slits
ion chamber
sample positioner (x-y-z stage)optical microscope (10x to 50x) withvideo systemfluorescence detector (WDS)
The Wavelength Dispersive Spectrometer (Oxford WDX-600)This detector uses a Johansson geometry Rowland circle to analyze fluorescent x-rays. The sample, bent crystal analyzer, and detector slits all lie on a circle, with the angle between sample and detector and crystal lattice spacing selecting the accepted energy. LiF(200) and (220) crystals are typically used for hard x-ray energies. Tandem proportional counters (one sealed with 2atm Xe, and one using flowing P-10 gas) are the detectors. The energy resolution at 6KeV is ~10eV, and the detector will not saturate as solid-state detectors are prone to do.
Though the solid-angle is small, the dynamic range and resolution make this detector an excellent complement to traditional solid-state fluorescence detectors.
Examples of its use are shown throughout this poster.
Here is a photograph and an x-ray fluorescence map of Cs (the L line) of a cross-cleavage plane of biotite exposed to a Cs-rich solution. This natural mica contains trace amounts of many transition metals including Ti, and large amounts of Ca and Fe, making a solid-state detector difficult to use for such a map.
S Sutton, M Rivers, P Eng, M Newville, U. Chicago
micro-XRF, XANES, and EXAFS Measurements with a Wavelength Dispersive Spectrometer
Above is the XRF spectra for this W-rich sample measured with the WDS. Using a Ge or Si solid-state detector, the Re L line would be a shoulder on the W L line, the detector would tend to saturate from the unwanted W fluorescence, and the Re XAFS would essentially impossible to measure.
The WDS allows us to isolate the Re L line and measure the XAFS of this previously “impossible” sample:
XRF and XAFS measurements in many natural and heterogeneous samples are complicated by the prescence of fluorescence lines from other elements near the line of interest. A common problem is to measure a minor element (say, Re) in the prescence of a major element just below it in Z (say, W) whose fluorescence line will be excited at the absorption edge of the minor element. (dilute amounts of Co, Ni, or Zn in the prescence of Fe pose similar problems).
Clockwise from lower left: measured (E), isolated EXAFS k(k), and the Fourier transform of the EXAFS |(R)|.
Re LIII-edge XAFS data for K7[ReOP2W17O61].nH2O measured with the WDS.
XRF Spectra of Au in FeAsS XAFS from a 13-element Ge detector
1000 x 200 m image of Cs fluorescence in biotite, made with a 5x5m beam, 5m steps, and 2sec dwell time per point (5hr collection time). The incident x-ray energy was 7.0KeV.
On the left is the EXAFS spectra for 1000ppm Au in FeAsS measured with a 13-element Ge detector (at PNC-CAT: APS sector 20). On the right is the same sample (at two different spots) measured with the WDS. The WDS supresses the As K-edge, making the Au LIII -edge much easier to see and analyze. The WDS spectra shows the Au to be heterogeneous -- sometimes metallic, and sometimes oxidized.
with J McKinley, J Zachara, S Heald (PNNL)
photograph of biotite cross-section
Cs fluorescece map of biotite cross-section
XAFS from the WDS
