A monochromatic confocal micro-x-ray fluorescence (μXRF) spectrometer for the lab

Area of Science:

• Analytical Chemistry
• Materials Science
• Physics

Background:

• Confocal micro-X-ray fluorescence (μXRF) is vital for 3D elemental distribution analysis.
• Conventional μXRF with polychromatic excitation faces quantification challenges and poor signal-to-noise ratios.
• Existing setups lack flexibility in excitation energy and portability.

Purpose of the Study:

• To develop an improved confocal μXRF setup addressing limitations of polychromatic excitation.
• To maintain high spatial resolution while enhancing quantification and signal quality.
• To ensure flexibility for various excitation energies and potential relocation.

Main Methods:

• Designed a new μXRF system featuring a monochromatic beam generated by an x-ray tube and a parallel beam-mirror.
• Incorporated a confocal setup with polycapillary optics for both source and detector sides, achieving ~15 μm focus.
• Enabled non-confocal measurements by exchanging a polycapillary with a custom collimator.

Main Results:

• Demonstrated the system's capability using a molybdenum tube and Mo-Kα radiation.
• Established detection limits for elements Ca-Pb in both confocal and non-confocal modes (e.g., As: 1 μg/g non-confocal, 20 μg/g confocal).
• Validated quantification accuracy using NIST standard reference materials and ATI-QUANT software, showing good agreement with certified values.

Conclusions:

• The new monochromatic confocal μXRF setup significantly improves quantification and signal quality.
• The system offers flexibility and maintains high spatial resolution for elemental analysis.
• Results confirm the setup's reliability for analyzing technical and biological samples.