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Milli X-Ray Fluorescence Spectrometer


The Eagle III Micro XRF unit is similar to a traditional XRF unit, with the primary difference being that the X-rays are focused by a polycapillary optic into a spot nominally 50 µm in size. The small, focused spot allows users to do X-ray imaging and microanalysis of a wide variety of samples where surface composition is of interest. Unlike electron beam instruments, the XRF can produce X-ray images at atmospheric pressure, and can analyze entire specimens 10 cm x 10 cm in size. Equipped with an EDAX EDS system, the system has detection limits well below 100 ppm for most elements, and below 50 ppm for transition metals such as iron, copper and zinc. Elements lighter than aluminum (Al Kalpha = 1.487 keV) are heavily absorbed by the 25 µm thick beryllium window in front of the detector, so the analysis of light elements is not possible. The system uses a 50 W rhodium tube with a maximum accelerating voltage of 40 keV and a maximum current of 1 mA. X-ray imaging is traditionally done with count rates of 20,000 counts per second, and X-ray images are collected for anywhere between 5 hours and 5 days. Showing remarkable stability and high stage reproducibility, the Eagle III has proven exceptionally useful in pre-imaging large samples. This technique, known as "Road Mapping" allows the analyst to identify areas of interest in images produced by the Eagle III after scanning over the entire sample. Those areas of interest are then analyzed using a variety of other microanalytical techniques. An advantage of using the Eagle III for "Road Mapping" is that the X-ray beam does not damage the sample in any way, and samples can even be analyzed in protective bags.

Specifications / Capabilities:

  • 50 W rhodium tube with maximum operating potential of 40 keV, 1 mA
  • Polychromatic 50 µm spot
  • Maximum analysis area of 10 cm x 10 cm
  • EDAX 30 mm2 Si(Li) detector. Resolution at 20,000 cps is ~170 eV (Mn Kalpha)
  • Analysis of elements from Al to Pu (Z = 13 – 94)
  • Analysis at ambient pressure and through bags or other protective media

Scientific Opportunities / Applications:

  • Analysis of cement and concrete samples
  • Imaging photographs, documents, paintings and other works of art
  • Compositional analysis of glasses, ceramics, thin films and wafers
  • Qualitative analysis of liquids, powders and particles
  • Particle searching and identification for dust, ash and contaminated surfaces
  • Analysis of biological specimens such as leaves, grasses and roots
  • General surface chemistry and compositional analysis.

Access Information:

Individual collaborative projects to address NIST measurement needs are possible when the work is consistent with the Surface and Microanalysis Science Division mission space. Contact Jeff Davis to discuss possible collaborations.

Associated Programs/Projects:

  • Doubling the service life of concrete
  • Analysis of historic metalpoint drawings
  • Combinatorial library analysis
Milli X-Ray Fluorescence Spectrometer
Credit: NIST

Name: Jeff Davis
Phone: 301-975-6988
Email: jeff.davis@nist.gov
100 Bureau Drive
Gaithersburg, MD  20899