High energy resolution fluorescence detected x-ray absorption spectroscopy: a new powerful structural tool in environmental & geochemistry sciences

International audienceThe study of the speciation of highly-diluted elements by X-ray absorption spectroscopy is experimentally extremely challenging, especially in geochemistry, environmental bio-geochemistry and Earth sciences. Here we present an innovative synchrotron spectroscopy technique, namely high energy resolution fluorescence detected X-ray absorption spectroscopy (HERFD-XAS). Within this approach, measuring the XAS signal in fluorescence mode with a Crystal Analyser Spectrometer (CAS), with a ~1 eV energy resolution, allows to overcome the restrictions on sample concentrations that can be typically conventionaly measured (Proux et al. 2017). On the BM30b beamline (ESRF, Grenoble, France), we developed a CAS in the Johann’s geometry (Llorens et al., 2012). This spectrometer is now on a dedicated beamline (BM16) and opened to regular users since January 2017. The new opportunities brought by this high resolution spectroscopy are i) the possibility to study ultra-diluted elements by filtering with a great efficiency the background photons and ii) to improve the sensitivity of the measurement with the acquisition of better resolved XANES spectra. This is a major technological advance with strong benefits for the study of highly-diluted elements with XAS, and opens new possibilities to explore the speciation of a target chemical element at natural concentration levels, which is critical in the fields of environmental and bio-geochemistry sciences.Llorens et al. (2012) Rev. Sci. Instrum. 83:063104 Proux et al. (2017) J. Environ. Quality (in press)

High energy resolution fluorescence detected x-ray absorption spectroscopy: a new powerful structural tool in environmental & geochemistry sciences

International audienceThe study of the speciation of highly-diluted elements by X-ray absorption spectroscopy is experimentally extremely challenging, especially in geochemistry, environmental bio-geochemistry and Earth sciences. Here we present an innovative synchrotron spectroscopy technique, namely high energy resolution fluorescence detected X-ray absorption spectroscopy (HERFD-XAS). Within this approach, measuring the XAS signal in fluorescence mode with a Crystal Analyser Spectrometer (CAS), with a ~1 eV energy resolution, allows to overcome the restrictions on sample concentrations that can be typically conventionaly measured (Proux et al. 2017). On the BM30b beamline (ESRF, Grenoble, France), we developed a CAS in the Johann’s geometry (Llorens et al., 2012). This spectrometer is now on a dedicated beamline (BM16) and opened to regular users since January 2017. The new opportunities brought by this high resolution spectroscopy are i) the possibility to study ultra-diluted elements by filtering with a great efficiency the background photons and ii) to improve the sensitivity of the measurement with the acquisition of better resolved XANES spectra. This is a major technological advance with strong benefits for the study of highly-diluted elements with XAS, and opens new possibilities to explore the speciation of a target chemical element at natural concentration levels, which is critical in the fields of environmental and bio-geochemistry sciences.Llorens et al. (2012) Rev. Sci. Instrum. 83:063104 Proux et al. (2017) J. Environ. Quality (in press)

A new high temperature reactor for operando XAS: Application for the dry reforming of methane over Ni/ZrO 2 catalyst

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High energy resolution fluorescence detected x-ray absorption spectroscopy: a new powerful structural tool in environmental & geochemistry sciences

International audienceThe study of the speciation of highly-diluted elements by X-ray absorption spectroscopy is experimentally extremely challenging, especially in geochemistry, environmental bio-geochemistry and Earth sciences. Here we present an innovative synchrotron spectroscopy technique, namely high energy resolution fluorescence detected X-ray absorption spectroscopy (HERFD-XAS). Within this approach, measuring the XAS signal in fluorescence mode with a Crystal Analyser Spectrometer (CAS), with a ~1 eV energy resolution, allows to overcome the restrictions on sample concentrations that can be typically conventionaly measured (Proux et al. 2017). On the BM30b beamline (ESRF, Grenoble, France), we developed a CAS in the Johann’s geometry (Llorens et al., 2012). This spectrometer is now on a dedicated beamline (BM16) and opened to regular users since January 2017. The new opportunities brought by this high resolution spectroscopy are i) the possibility to study ultra-diluted elements by filtering with a great efficiency the background photons and ii) to improve the sensitivity of the measurement with the acquisition of better resolved XANES spectra. This is a major technological advance with strong benefits for the study of highly-diluted elements with XAS, and opens new possibilities to explore the speciation of a target chemical element at natural concentration levels, which is critical in the fields of environmental and bio-geochemistry sciences.Llorens et al. (2012) Rev. Sci. Instrum. 83:063104 Proux et al. (2017) J. Environ. Quality (in press)

High Resolution Spectroscopy on an X-ray Absorption Beamline

International audienceAbstract A bent crystal spectrometer based on the Rowland circle geometry has been tested on the BM30b/FAME beamline at the European Synchrotron Radiation Facility. The energy resolution of the spectrometer (1.3eV at the Cu K1 energy, i.e. 8047.78eV) allows to perform different kinds of measurements, including X-ray Absorption Spectroscopy, Resonant Inelastic X-ray Scattering and X-ray Raman Scattering experiments. The simplicity of the experimental device makes it easily implemented on a classical X-ray absorption beamline

High energy resolution five-crystal spectrometer for high quality fluorescence and absorption measurements on an X-ray Absorption Spectroscopy beamline

International audienceFluorescence detection is classically achieved with a solid state detector (SSD) on x-ray absorption spectroscopy (XAS) beamlines. This kind of detection however presents some limitations related to the limited energy resolution and saturation. Crystal analyzer spectrometers (CAS) based on a Johann-type geometry have been developed to overcome these limitations. We have tested and installed such a system on the BM30B/CRG-FAME XAS beamline at the ESRF dedicated to the structural investigation of very dilute systems in environmental, material and biological sciences. The spectrometer has been designed to be a mobile device for easy integration in multi-purpose hard x-ray synchrotron beamlines or even with a laboratory x-ray source. The CAS allows to collect x-ray photons from a large solid angle with five spherically bent crystals. It will cover a large energy range allowing to probe fluorescence lines characteristic of all the elements from Ca (Z = 20) to U (Z = 92). It provides an energy resolution of 1-2 eV. XAS spectroscopy is the main application of this device even if other spectroscopic techniques (RIXS, XES, XRS, etc.) can be also achieved with it. The performances of the CAS are illustrated by two experiments that are difficult or impossible to perform with SSD and the complementarity of the CAS vs SSD detectors is discussed