Depth Profiling of Element Concentrations in Stratified Materials by Confocal Microbeam X-ray Fluorescence Spectrometry with Polychromatic Excitation

Abstract

The confocal microbeam X-ray fluorescence technique is a well-established analytical tool that is widely used for qualitative and quantitative analysis of stratified materials. There are several different reconstruction methods dedicated to this type of samples. However, these methods are applicable with monochromatic excitation only. The full description of matrix effects and geometrical effects for polychromatic X-ray photons in confocal geometry is a demanding task. In the present paper, this problem was overcome by the use of effective energy approximation. The reduction of the whole energy dimension into one effective value eliminates the necessity of integration over the primary beam energy range for a number of basic parameters. This simplification is attainable without loss of the accuracy of analysis. The proposed approach was validated by applying it to the reconstruction of element concentration depth profiles of stratified standard samples measured with tabletop confocal microbeam X-ray fluorescence setup and by comparing the obtained results of two independent algorithms.

Data quantification procedures for a bench‐top elemental microimaging of brain specimens for the clinical studies on the obesity treatment by transcranial direct current brain stimulation

“…The spectral distribution of the primary radiation emitted from the X-ray tube, filtered by the polycapillary optics, was calculated by the scheme presented in Wrobel et al [29] Herein, the effective energy of~10 keV was found. *the boundary water fractions in the brain structures studied are in italics …”

Non-Invasive and Non-Destructive Examination of Artistic Pigments, Paints, and Paintings by Means of X-Ray Methods

“…Sequential series of confocal XRF measurements along lines and planes allows to visualize the distribution of chemical elements of interest in one or two dimensions, creating, for example, virtual depth profiles, and two-or three-dimensional distributions inside the materials of interest [23,100,101]. After its original introduction at synchrotron radiation facilities [97,[101][102][103][104][105], the feasibility of performing confocal XRF measurements using tube sources was demonstrated by several groups around the world [106][107][108][109][110], along with appropriate deconvolution, quantification, and simulation models [111][112][113][114][115][116][117][118]. Several papers have been recently been published where confocal XRF measurements are exploited for sub-surface examination of painted works of art [119][120][121][122][123][124], next to pottery [125], coins [86], stained glass [126,127], painted metal sheet [128], and natural rock samples [129].…”

2015 Atomic Spectrometry Update – a review of advances in X-ray fluorescence spectrometry and their applications

“…Cordes et al 413 reported the use of laboratory-based X-ray techniques for the non-destructive elemental quantication of polymerembedded thin lms. Wrobel et al 415 performed depth proling of element concentrations in stratied materials by confocal m-XRF spectrometry with polychromatic excitation. Confocal m-XRF and nano-CT were successfully coupled for these measurements in order to meet these sensitivity and spatial resolution specications necessary for characterising thin lms.…”

“…Multilayered paint fragments of a car were analysed non-destructively to demonstrate that this confocal m-XRF instrument could be used in the discrimination of the various layers in multilayer paint systems. Wrobel et al 415 performed depth proling of element concentrations in stratied materials by confocal m-XRF spectrometry with polychromatic excitation. The authors extended a method, well established for monochromatic radiation, to polychromatic radiation by effective energy approximation.…”