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CI1, CM2, CR2 and ungrouped C2 carbonaceous chondrites contain a few percent of insoluble organic matter (IOM) which could provide clues on the organic chemistry of nebular and/or protostellar environments. These chondrites also have experienced complex hydrothermal processes on parent bodies [1-3]. A major issue is the understanding of IOM compositional and structural changes due to hydrothermalism. Chemical variability has been reported among various IOMs, and so far interpreted as the consequence of oxidation processes [4; 5]. The primordial diversity of organic precursors could be also involved.

The study of very ancient microfossils has recently raised contentious issues regarding interpretation of the biogenicity of the structures. In situ investigation of certain elements such as sulfur within potential microfossils is a powerful complement to other methods of investigation that can provide valuable information on biogenicity. We present here a first such study on Precambrian microfossils from the 700–800-My-old Neoproterozoic Draken Formation, Svalbard, using scanning X-ray microscopy (SXM) in the fluorescence mode and X-ray absorption near edge spectroscopy (XANES) at the sulfur K-edge. SXM allowed mapping of up to 300 ppm of probably endogenous sulfur within the kerogenous walls of Myxococcoides chlorelloidea microfossils. XANES showed that the sulfur is most likely contained in heterocyclic organic compounds, such as thiophene(s).

International audience; Fluid inclusions are studied using synchrotron radiation induced μ-X-ray fluorescence (μ-SR-XRF). We analyse inclusions from the Brusson gold deposit, Italy. Several two-phase (liquid plus gas) inclusions of a single generation are used to compare a new standardless quantification procedure to previously published internal and external standardisation procedures. The three procedures are based on an infinite homogeneous plane layer and the calculations are performed with a non-iterative fundamental parameter method. Results show a good agreement between the average of the calculated concentrations obtained with the three procedures and the corresponding crush-leach analysis. Cl, K, Ca, Fe, Cu, Zn and As crush-leach concentrations are within error bars of the μ-SR-XRF concentration estimates. Br crush-leach content is above μ-SR-XRF estimates. Ti, Cr, Mn, Ni and Pb were detected with μ-SR-XRF technique only. These elements show different concentrations from one inclusion to another, suggesting heterogeneous trapping of tiny, infra-microscopic solid phases. The good correspondence between the results obtained using the three calibration procedures show that accurate standardless quantitative analysis of individual fluid inclusions is achievable. Statistical error calculation of the three procedures shows that the standardless quantification method yields more accurate results than the internal or external standard procedures. Uncertainties on inclusion depths strongly affect calculated light element concentrations (Cl to Ca), whereas Mn and heavier elements concentration estimates are more sensitive to errors on fluid inclusion thickness. Uncertainties of ± 1 μm or less on fluid inclusion thickness and depth yield statistical errors of not, vert, similar 50% on Cl concentration estimates and lower than 20% on transition metals. This new standardless-μ-SR-XRF based quantification procedure is more precise than the previously established ones and is efficiently applied to multielementary analysis (Cl to Pb) of diluted individual fluid inclusions.

High-pressure structural transitions in nanocrystalline systems are of significant interest as models of first-order phase transitions. We demonstrate size-induced lattice expansion and significant atomic rearrangements in the crystal structure of nanocrystalline high-pressure baddeleyite-TiO2. The α-PbO2 structured TiO2 recovered after dozens of pressure cycles in the α-PbO2-baddeleyite pressure field displayed elongate 25–35 nm crystallites, compared to starting 34-nm anatase crystallites, suggesting crystallite coherency across anatase, baddeleyite, and α-PbO2 structures and ‘single structural domain’ behavior of the nanocrystalline system.

Different reconstruction techniques are used to reconstruct the distribution of the physical characteristics, describing a sample under investigation, from a set of tomographic projections. We present a technique for the evaluation of the reconstruction quality. The technique is based on the comparison of two images (phantom and reconstructed image) by means of the correlation coefficient and of the mean square error between them. In parallel, the correlation coefficient and mean square error are calculated for the wavelet transforms of the phantom and reconstructed images. The scales for the wavelet transform are chosen in agreement with the major geometric parameters of the phantom. Then the correlation coefficient of the wavelet transform with the chosen scale yields an evaluation of the quality of the phantom parameters reconstruction. The accuracy of the parameters reconstruction is determined by the mean square error for the selected scale. The phantom used for the analysis is a medium with randomly distributed grains. The distribution is characterized by two parameters: grain size and grain density (average number of grains per unit area). The parameters are used as the scales for the wavelet transform calculation. We make a comparison of the Algebraic Reconstruction Technique (ART) and the Filtered Back Projection Algorithm.

A crystal spectrometer has been constructed in the Focusing Compensated Asymmetric Laue geometry covering the energy range between 30 and 120 keV. We summarize the crystal optics and show the usefulness of the instrument for spectroscopy of stationary and fast moving X-ray sources. Results are reported from several tests employing a 169 Yb gamma-ray source and the Lyman radiation of one-electron Au 78+ ions travelling at a velocity corresponding to β = v / c o ≈0.44.

Quantitative estimate of elemental composition by spectroscopic and imaging techniques using X-ray fluorescence requires the availability of accurate data of X-ray interaction with matter. Although a wide number of computer codes and data sets are reported in literature, none of them is presented in the form of freely available library functions which can be easily included in software applications for X-ray fluorescence. This work presents a compilation of data sets from different published works and an xraylib interface in the form of callable functions. Although the target applications are on X-ray fluorescence, cross sections of interactions like photoionization, coherent scattering and Compton scattering, as well as form factors and anomalous scattering functions, are also available.

A natural shockwave event led to the formation of a new crystalline polymorph of carbon in gneisses from the Popigai crater, Russia. The new species occupies the interior of a multiphase assemblage and is entirely enveloped by lonsdaleite and graphite. Polishing hardness of this new phase is greater than that of lonsdaleite. Micro-beam synchrotron X-ray diffraction, imaging and fluorescence studies revealed a pure transparent carbon phase. The diffraction pattern is indexed in terms of a cubic cell (a = 14.697 Angstrom, space group Pm3m.). This species was neither encountered in static or dynamic high-pressure experiment nor predicted by theoretical calculations. (C) 2003 Published by Editions scientifiques et medicales Elsevier SAS on behalf of Academie des sciences.

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.

We present a synchrotron X-ray diffraction study of pressure-induced changes in nanocrystalline anatase (with a crystallite size of 30–40 nm) to 35 GPa. The nanoanatase was observed to a pressure above 20 GPa. Direct transformation to the baddeleyite-TiO 2 polymorph was seen at 18 GPa. A fit of the pressure versus volume data to a Birch–Murnaghan equation yielded the following parameters: zero-pressure volume, V 0 =136.15 A 3 , bulk modulus, K T =243(3) GPa, and the pressure derivative of bulk modulus, K ′=4 (fixed). The bulk modulus value obtained for the nanocrystalline anatase is about 35% larger than that of the macrocrystalline counterpart.

The Particle Impact Experiment (PIE) was flown for 11 months outside the MIR station in 1996–97. The grains, both of extraterrestrial and terrestrial origins, captured in the low-density foam collectors, were investigated for using Synchrotron X-ray microfluorescence (SXμF) techniques, developed at LURE (Orsay, France) and ESRF (Grenoble, France). The positions of grains a few microns large are known at better than 10 μm . Chemical identification is arduous; only Z>20 elements are identified and, for the heavy elements, only a rough estimate of their abundances inside the grains can be given. We use the Fe/Ni ratio as the criterion allowing to distinguish between terrestrial orbital debris (OD) and extraterrestrial grains. In the 60 cm 2 of foam analyzed by this technique, we identified two or three probable extraterrestrial grains and confirmed the existence of an OD cloud, rich in Fe–Ni alloys, crossed by the MIR station. SXμF is a powerful, non-destructive, technique of in situ identification of absorbing grains trapped in a material otherwise transparent to X-rays. It is the only analytical procedure for foams, opaque to visible light. For aerogels, exposed in many space missions and used as grain collectors in the STARDUST mission, the grains positions can be known after an optical scanning; SXμF appears as the last step for the high resolution in situ identification (size, shape, chemical composition) of the grain before its eventual extraction by microtunneling techniques.

The iron oxidation states and its environment in volcanic silicate glasses have been studied by combining micro-X-ray absorption near edge structure (XANES) experiments at the iron K-edge in silicate glass fragments and glass inclusions trapped during the crystal growth. Experiments were performed at the ESRF (ID22 beam-line) – a third generation synchrotron – using a focused beam (2×10 μm 2 ) together with a high brilliance and a good energy resolution. The selected silicate glasses, basaltic in composition, contain between 5.5 and 8 wt% total Fe. In all XANES spectra, pre-peaks exhibit a multi-component structure, which is the convolution of information related to the valence state of iron (2+,3+), the site geometry and transition types. The Fe3+/ΣFe ratio of silicate glass fragments deduced from the XANES spectra is correlated to values determined by chemistry on bulk samples within the range 0.05–0.85. XANES spectra from glass inclusions hosted in natural olivine crystals may be interpreted considering the glass fragments as reference samples.

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 ( 2×5 μm 2 ) is successively tuned at 11 keV, below the LIII 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.

Recent improvements in synchrotron X-ray sources (third generation) and in X-ray focusing elements have been realized. This result in delivering highly collimated quasi-monochromatic X-ray beams with tunable energy and beam focused down to sub-micrometer diameter. Preliminary results in the μ-SXRF of single cells were obtained in the hard X-ray range. “Pink”-beam and compound refractive lenses were used resulting in a 1×10 μm 2 (vertical×horizontal) beam size with a flux ∼5×10 10 photon/s / μm 2 . The experiment confirmed that high energy, high intensity X-rays were well suited for microanalysis of sensitive biological specimens such as freeze-dried cells. Results show that the synchrotron microprobe set-up at ESRF allows high sensitivity in trace element measurements for cells treated with pharmacological doses of an iodine-labeled anticancer drug.

International audience; The concentration and spatial distribution of relatively dilute (10 to 100 ppm) trace metals (Cu, Zn and As) were determined for individual fluid inclusions from a gold-quartz vein at Brusson, western Italian Alps, using synchrotron radiation X-ray fluorescence (SXRF). The analyses were performed on beamline ID-22 Micro-FID (Fluorescence, Imaging, Diffraction) of the European Synchrotron Research Facility (ESRF) Grenoble, France. The experimental set-up ensured a focal spot at the sample position of 2×7 μm and a flux of 1010 photons/s. Fluorescence X-ray maps were collected for several fluid inclusions. An example of the distribution of As in a fluid inclusion oriented at high angle to the wafer surface is presented. For each X-ray fluorescence spectrum, the (Kα/Kβ)As ratio of As was used as a means of estimating the thickness of quartz traversed by the photon beam. This value was used in turn for correcting As count rates. The correction procedure resulted in uniformising the count rates of As in the liquid portion of the inclusion and allowed visualizing the vapour bubble which contains only trace amounts of As. The strategy for computing the composition of the inclusion fluid was to use one element from crush leach analysis (As) as an internal standard to calculate the concentrations of the other cations (Cu and Zn) present in the solution. Results of this calculation show that element concentration estimates calculated using SXRF spectra are in relatively good agreement with those determined by crush-leach analysis. This indicates that the fluid trapped in the sample studied was homogeneous with respect to electrolyte composition. These results indicate that third generation synchrotron light source is a promising technique for tracking trace metals in individual inclusions (down to the tenths of ppm level) and, hence, as an invaluable tool for reconstructing the relative chronology of paleo-hydrothermal events responsible for the concentration of economic resources.

We have developed an X-ray Fluorescence Holography (XFH) setup at the European Synchrotron Radiation Facility (ESRF). The main difficulty inherent to XFH is that the holographic signal is in the low 10 −3 range compared to the background isotropic fluorescent radiation. This requires a very pure fluorescent signal and the highest possible count rate. Therefore, we designed a focusing analyser system with large solid angle acceptance. The photons of the focused beam were counted by an avalanche photodiode in single-photon counting mode up to a few MHz. At even higher intensity, we switched to a Si diode working in the photocurrent mode. Due to the relatively weak requirements on the bandwidth of the exciting incident radiation, we could directly use the undulator beam, discriminating lower harmonics by an absorber and higher ones by reflecting the beam on a Si mirror. By developing a fast, continuous “spiral” scanning technique, a full hologram could be recorded in 30 sec.