13 ID-E Beamline
X-ray Absorption Fine Structure (µXAFS)
Microfocused XAFS to determine the speciation (local chemistry, quantitative determination of the local geometric structure around the absorbing atom) of the elements. Depending on concentrations, both µ-XANES and µ-EXAFS are possible as is oxidation state mapping of materials. Both Si(111) and Si(311) DCM crystal sets are available depending on the energy resolutions required for the experiment.
X-ray Fluorescence (µXRF)
Compositional analysis and mapping for elements with X-ray emission energies between ~ 2-28 keV. Multiple elements can be analyzed simultaneously. MDL is highly dependent on sample, spectral overlaps, detector placement and absorbers, but ppb level detection is possible. Mapping utilizes continuous scanning approach with practical pixel times as low as 5-10 milliseconds. Non-destructive compositional mapping (diffusion, zonation), sector zoning in minerals, compositions of microparticles (soils, micrometeorites, aerosols), trace element distributions in cells, etc. Samples can be analyzed in air, in a moist or wet state, biological samples can be analyzed intact.
Cathodoluminescence images show zircons formed in granite melts, start from a core and add layers as granite and other phases crystallize from the melts. Does Ce concentration and valence vary with these growth zones ? Nick Tailby, Dustin Trail, Rennselaer Polytechnical Institute.
X-ray Diffraction (µXRD)
Microdiffraction analysis for mineral identification with spatial resolutions of <1 µm. Area detector readout at frame rates < 100 msec per frame possible using Perkin-Elmer amorphous silicon area detector, allowing for dynamic diffraction studies, diffraction mapping and tomography, etc.
Fluorescence Computed Microtomography (fCMT)
Element specific X-ray fluorescence tomography with micrometer spatial resolution. Our fCMT analysis employs a continuous scanning approach similar to that utilized in fast 2D mapping, with practical pixel times as low as 10-20 milliseconds. X-ray fluorescence (full EDS) from a sample is measured as it is translated (X) and rotated (theta) through the focused beam to generate a sinogram (top image shown below). In our implentation of the technique we use theta as the fast scan direction to improve stability. Tomographic slices of XRF intensity through the object are then reconstructed following the same methods utilized for absorption tomography.
Using fCMT methods researches can non-destructively examine trace element distributions in materials without the need for physical sectioning. The bottom image below of a reconstructed slice through a 150 micrometer diameter Arabidopsis seed (Punshon – Dartmouth College) shows the high resolution imaging possible at elemental concentrations below 100 ppm.
- Vortex ME4 silicon drift diode array detector
- Quantum Xpress 3 digital X-ray processors supporting ultrahigh-speed, on-the fly-mapping modes
- Perkin Elmer XRD 1621 amorphous silicon area detector
- MAR 165 CCD area detector
- MAR 345 Image Plate area detector
- ADC ion chambers
- Microspec Wavelength Dispersive Detector
- Peltier-cooled sample stage
- Helium sample environments
- Navitar Ultraviolet imaging illuminator
- Prosilica visible-light CCD sample imaging system (~0.5 mm field of view)
- Access to GSECARS laboratories including microscopy instrumentation, wet lab, fume hood, laminar-flow hood, glove box, sample prep areas.
- Offline Sample Registration and Coordiate System (OSCAR) provides users an offline microscope in the beamline control area to view samples and select ares for X-ray analysis before putting the sample in the X-ray beam.
|Source||3.5 cm undulator|
|Monochromator Type||cryo DCM, Si(111), Si(311)|
|Energy Range||2.4-28 keV|
|resolution (deltaE/E)||1.1 x 10-4|
|flux (photons/sec)||6 x 1012 @ 10 keV|
X-ray Absorption Fine Structure (XAFS)
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