Comparison of two confocal micro-XRF spectrometers with different design aspects

Confocal micro-X-ray fluorescence analysis for difference identification of ceramic samples

A nondestructive analytical method for difference identification is required in the research fields such as forensic science or archeology. An X-ray fluorescence (XRF) analysis is one of feasible techniques for this purpose. Micro-XRF using an X-ray micro-beam gives elemental distributions by scanning the samples. A confocal micro-XRF (CM-XRF) technique is a unique analytical technique to analyze limited volume. CM-XRF enables elemental depth imaging and elemental profiling in depth nondestructively. Therefore, CM-XRF has been applied for various samples such as industrial samples, paintings, forensic samples, food materials, and human hairs. CM-XRF technique would be a suitable method for difference identification because the CM-XRF gives detailed information on elemental distribution not only on the surface of the sample but also in depth. We developed CM-XRF instrument in the laboratory and applied to two very similar ceramics samples. It showed differences in the intensity profiles of Fe and Mn for blue paintings on the ceramics. In addition, depth elemental analysis revealed different depth profiles especially of Co and Zn for both samples. These results suggest that CM-XRF provides useful information for the identification of ceramic samples.

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

Recent studies are concisely reviewed, in which X-ray beams of (sub)micrometre to millimetre dimensions have been used for non-destructive analysis and characterization of pigments, minute paint samples, and/or entire paintings from the seventeenth to the early twentieth century painters. The overview presented encompasses the use of laboratory and synchrotron radiation-based instrumentation and deals with the use of several variants of X-ray fluorescence (XRF) as a method of elemental analysis and imaging, as well as with the combined use of X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS). Microscopic XRF is a variant of the method that is well suited to visualize the elemental distribution of key elements, mostly metals, present in paint multi-layers, on the length scale from 1 to 100 μm inside micro-samples taken from paintings. In the context of the characterization of artists' pigments subjected to natural degradation, the use of methods limited to elemental analysis or imaging usually is not sufficient to elucidate the chemical transformations that have taken place. However, at synchrotron facilities, combinations of μ-XRF with related methods such as μ-XAS and μ-XRD have proven themselves to be very suitable for such studies. Their use is often combined with microscopic Fourier transform infra-red spectroscopy and/or Raman microscopy since these methods deliver complementary information of high molecular specificity at more or less the same length scale as the X-ray microprobe techniques. Since microscopic investigation of a relatively limited number of minute paint samples, taken from a given work of art, may not yield representative information about the entire artefact, several methods for macroscopic, non-invasive imaging have recently been developed. Those based on XRF scanning and full-field hyperspectral imaging appear very promising; some recent published results are discussed.

µXRF Elemental Mapping of Bioresorbable Magnesium-Based Implants in Bone

This study investigated the distribution of the elemental constituents of Mg-based implants at various stages of the degradation process in surrounding bone tissue, with a focus on magnesium (Mg), as the main component of the alloy, and yttrium (Y), due to its potential adverse health effects. The measurements were performed on the implant-bearing thin sections of rat bone in a time series of implant degradation between one and 18 months. Micro X-ray fluorescence analysis (μXRF) with a special spectrometer meeting the requirements for the measurements of low-Z elements was used. It was found that the migration and accumulation behaviour of implant degradation products is element-specific. A sharp decrease in Mg was observed in the immediate vicinity of the interface and no specific accumulation or aggregation of Mg in the adjacent bone tissue was detected. By contrast, Y was found to migrate further into the bone over time and to remain in the tissue even after the complete degradation of the implant. Although the nature of Y accumulations must still be clarified, its potential health impact should be considered.