Ingerle, D., Iro, M., Hradil, K., Swies, J., Streli, C., & Wobrauschek, P. (2022, 0 0). A monochromatic confocal micro X-ray Fluorescence (µXRF) spectrometer using polycapillaries for the lab [Conference Presentation]. EXRS2022, Brügge, Belgium.
Confocal μXRF is a powerful tool to analyze the spatial distribution of major, minor and trace
elements in 3 dimensions. Due to its non-destructiveness, confocal μXRF is suited for a wide
range of applications, including biological, geological or cultural heritage samples.
A typical (confocal) μXRF measurement in the lab uses polychromatic excitation, which
complicates quantification and fundamental parameter based corrections, and furthermore
reduces peak-to-background ratios due to the scattered bremsstrahlung. The goal for the new
setup was to remedy these problems, but without sacrificing spatial resolution, and moreover
to keep it flexible for transportation and different excitation energies.
The source assembly consists of a water-cooled fine-focus XRD tube and a parallel beam-
mirror, which produces a quasi-parallel, monochromatic beam. The presented results were
obtained at the Atominstitut using a Molybdenum anode and a fitting mirror for Mo-Kα, but it
is intended also to use a combination for Cu-Kα, which is available at the X-Ray Center of
TU Wien.
The confocal setup itself consists of two polycapillary half-lenses, one for the source side and
one for the detector side, where a 50 mm2 SDD is mounted. Both polycapillaries have a focus
size of ~15 μm for Mo-Kα. The second polycapillary can also be exchanged for a custom-
designed collimator, in order to perform (non-confocal) μXRF. The alignment of the sample
is facilitated by an optical microscope with camera and a second down-looking camera.
Details of the technical setup 1 as well as results from technical and biological samples and
a comparison with a polychromatic μXRF setup will be presented.
1 Ingerle, D., Swies, J., Iro, M., Wobrauschek, P., Streli, C., & Hradil, K. (2020). A
monochromatic confocal micro-x-ray fluorescence ( μ XRF ) spectrometer for the lab.
Rev.Sci.Instrum., 91, 123107. https://doi.org/10.1063/5.0028830