[en] Materials science deals with the study of the morphology of samples, their chemical composition and the relation between both. One general problem is the preservation of the sample throughout the different analyses, like it is often the case for classical chemical analysis. Destruction-free chemical speciation in three dimensions with micrometer resolution can be achieved by combining X-ray spectroscopy and imaging techniques. Highly brilliant radiation is needed for this purpose available at 3rd generation synchrotrons such as the ESRF. X-ray absorption near-edge spectroscopy (XANES) is a non-destructive well-known and established technique in chemistry. By scanning the X-ray energy in the vicinity (50-100 eV) of the absorption edge of an element, information can be obtained about the oxidation state of the probed atoms. The (conventional) technique mainly employed until now applies to homogeneous, specifically prepared flat samples where the measured signal can be considered as the average over the whole irradiated volume. This restriction for samples is partially released when the XANES method is combined with imaging techniques. 2D resolved data is acquired using area detectors or by scanning with a focussed beam. X-ray absorption tomography is a method of choice for investigating the 3D structure of objects and its dual energy version is used for getting information about the 3D distribution of a given element within the sample. Although the combination of XANES and tomography seems to be a natural extension of dual-energy tomography, in practice several experimental problems have to be overcome in order to obtain useable data. In the following we describe the results of XANES imaging and tomography obtained measuring a phantom sample of pure molybdenum compounds using a FreLoN 2000 camera system at the ESRF undulator beamline ID22. This system allowed making volume resolved distinctions between different oxidation states with spatial resolution in the micrometer range

[en] The aim of this study was to establish the feasibility of obtaining 3D elemental images of fluid inclusions, which consist of multiphase and irregular objects trapped in a host mineral. These experiments are based on the fluorescence micro-tomography technique, which combines X-ray fluorescence measurements and 2D tomographic reconstruction algorithms. For this purpose, multiphase aqueous fluid inclusions were synthesized in fractured quartz crystal within gold capsule at high temperature and pressure. A single fluid inclusion was isolated in a tiny quartz parallelepiped, polished on all its faces. On the basis of the parallel collection technique, the sample was successively scanned vertically over a few hundred micrometers, in steps of 3 μm and with an acquisition time of 1 s/point, and rotated by an angle of 2 deg. The 2D projection images, which consist in relative elemental concentration regions, provide the size and the location of the fluid inclusion as well as the elemental location and combination. By iterating the procedure along the horizontal rotation axis, full 3D elemental images can be obtained

[en] Among the X-rays emitted in collisions between slow fully stripped ions with solids, a structure well above the limit of the Lyman series is observed. For Ne¹⁰⁺ ions this spectral feature has an average energy of 1.8 keV and thus evidently results from the deexcitation of two K shell vacancies via a two electron 2s2p → 1s² transition with the emission of a single photon. (orig.)

[en] The new ID18F end-station at the European synchrotron radiation facility (ESRF) in Grenoble (France) is dedicated to sensitive and accurate quantitative micro-X-ray fluorescence (XRF) analysis at the ppm level with accuracy better than 10% for elements with atomic numbers above 18. For accurate quantitative analysis, given a high level of instrumental stability, major steps are the extraction and conversion of experimental X-ray line intensities into elemental concentrations. For this purpose a two-step quantification approach was adopted. In the first step, the collected XRF spectra are deconvoluted on the basis of a non-linear least-squares fitting algorithm (AXIL). The extracted characteristic line intensities are then used as input for a detailed Monte Carlo (MC) simulation code dedicated to XRF spectroscopy taking into account specific experimental conditions (excitation/detection) as well as sample characteristics (absorption and enhancement effects, sample topology, heterogeneity etc.). The iterative use of the MC code gives a 'no-compromise' solution for the quantification problem

[en] The ID18F microprobe end-station of the European Synchrotron Radiation Facility (ESRF) is dedicated to precise and reproducible quantitative X-ray fluorescence analysis in the ppm level with ≤5% accuracy for elements of Z≥19 and micron-size spatial resolution. In order to fulfill this requirement the precise monitoring and normalization of the intensity variation of the focused micro-beam is necessary. The various effects influencing the intensity variation, hence the stability of the μ-beam, were investigated by placing different detectors (miniature ionization chamber, photodiodes) into the monochromatic beam. The theoretical statistical error of the measured signal in each detector was estimated on the basis of the absorption and e^--ion-pair production processes and was compared with the measured statistical errors

[en] Chemical studies have shown that doxorubicin, a well-established anticancer agent, is a powerful iron chelator and the resultant iron-drug complex is an efficient catalyst of the conversion of hydrogen peroxide to the highly reactive hydroxyl radical. However, the intracellular complexation of doxorubicin with iron is still debated. Using nuclear microprobe analysis (NMPA), we previously observed in human ovarian cancer cells exposed to 20 μM iodo-doxorubicin (IDX) that iodine and iron cellular distributions were spatially correlated, suggesting a mechanism of intracellular iron chelation by the anthracycline compound. Because maximal plasma drug concentrations in patients are expected to be around 5 μM, NMPA and X-ray absorption near edge spectroscopy (XANES) experiments for iron speciation analysis were performed on cultured cells exposed to pharmacological doses of 2 μM IDX or doxorubicin

[en] Vases full of make-up are most often present in the burial furniture of Egyptian tombs dated from the pharaonic period. The powdered cosmetics made of isolated grains are analysed to identify their trace element signature. From this signature we identify the provenance of the mineral ingredients in the make-up and we observe different impurities in products, which have been demonstrated as synthetic substances by previous works. Focused X-ray micro-beam (2x5 μm²) is successively tuned at 11 keV, below the L_III absorption edge of Pb, and 31.8 keV for global characterisation of the metal impurities. The fluorescence signal integrated over each single grain is detected against the X-ray micro-diffraction pattern collected in transmission with a bi-dimensional detector. Furthermore, for galena grains rich in Zn, the XANES signal at the K-absorption edge of Zn shows its immediate nearest-neighbour environment

[en] The X-ray fluorescence microtomography method is presented, which is capable of virtually slicing samples to obtain cross-sections of their inner structure. High precision experimental results of fluo-tomography in 'pencil-beam' geometry with up to 1.2 μm resolution are described. Image reconstructions are based on either a simplified algebraic reconstruction method (ART) or the filtered back-projection method (FBP). Phantoms of inhomogeneous test objects as well as biological samples are successfully analyzed

[en] We report on n=3 to n=3 soft-x-ray transitions from the highest nuclear charge (Z=82) Na-like ions yet obtained. The results are tied to accurate calculations including screened QED contributions and confirm theoretical trends observed by Kim et al. [Phys. Rev. A 44, 148 (1991)]. Weak Ne-like and Mg-like lines are observed in an accelerator-based experiment in the energy range near 800 eV and compared to multiconfiguration Dirac-Fock calculations

[en] The algebraic technique of an element distribution reconstruction from fluorescence projections is described. The application of the software under development to the image reconstruction is demonstrated by processing thorium sinogram from a measurement of laser-ablated resin samples at the ESRF beam line ID22. (authors)