[en] Rare earths and copper systems were studied using X-ray absorption spectroscopy (XAS) and resonant inelastic X-ray scattering (RIXS). The use of monochromased synchotron radiation and improved energy resolution for RIXS made possible to obtain valuable information on the electronic structure in 4f, 5f and 3d systems. Experimental results for rare-earths (Ho, Gd, Cm, U, Np, Pu) were analyzed by atomic multiplet theory based on the Hartree-Fock calculations. The inelastic scattering structures in RIXS spectra at 5d edge of actinides found to be sensitive to actinide oxidation states in different systems. Comparison of experimental and calculated Cm 5d RIXS spectra gave direct information about valency of the 248-curium isotope in oxide. Scientific understanding of processes that control chemical changes of radioactive species from spent fuel is improved by studying interactions of actinide ions (U, Np, Pu) with corroded iron surfaces. RIXS measurements at the actinide 5d edge found to be sensitive to actinide oxidation states in different systems. Comparison of experimental and calculated Cm 5d RIXS spectra gave direct information about valency of the 248 curium isotope in oxide. Scientific understanding of processes that control chemical changes of radioactive species from spent fuel is improved by studying interactions of actinide ions (U, Np, Pu) with corroded iron surfaces. RIXS measurements at the actinide 5d edge indicate the reduction of U(VI), NP(V) and Pu(VI) to U(IV), Np(IV) and Pu(IV) by presence of iron ions. This thesis is also addressed to the study of changes in the electronic structure of copper films during interaction with synthetic groundwater solutions. The surface modifications induced by chemical reactions of oxidized 100 Angstrom Cu films with CL^-, SO₄^2- and HCO₃^- ions in aqueous solutions with various concentrations were studied in-situ using XAS. It was shown that the pH value, the concentration of Cl^- ion and presence of HC₃^- ion in the solutions strongly affect the speed of the corrosion reaction. The Cu 2p RIXS was used to distinguish between the species present on the copper surface while in contact with groundwater solution

[en] A preliminary Johann-type X-ray emission spectrometer has recently been installed and tested at the Rossendorf Beamline (ROBL). The spectrometer consists of a single spherically bent crystal analyzer and an avalanche photodiode detector positioned on the vertical Rowland cycle with 1 m diameter. The instrument has been tested at the Zr-K edge.

[en] This report gives a brief description of the quantitative uranium speciation performed by iterative transformation factor analysis (ITFA) of High Energy Resolution X-ray Fluorescence Detection (HERFD) data collected at the M_4_,_5 edge.

[en] Valence-band X-ray emission spectroscopy (XES) with a ''pink beam'', i.e. a beam with large energy bandwidth produced by a double-multilayer monochromator, is introduced here to overcome the weak count rate of monochromatic beams produced by conventional double-crystal monochromators. Our results demonstrate that - in spite of the large bandwidth in the order of 100 eV - the high spectral resolution of the Johann-type spectrometer is maintained, while the two orders of magnitude higher flux greatly reduces the required counting time. The short working distance Johann-type X-ray emission spectrometer and multilayer monochromator is available at ROBL.

[en] Actinide elements are of a high importance due to their application in nuclear energy. The investigation of the fundamental properties of actinides and especially Pu is crucial to understand their behaviour in the nuclear fuel cycle especially on the last stages related to the reprocessing and the waste disposal. It was previously shown that plutonium migrates in colloidal form in the subsurface environment with the distance of several kilometers from previously contaminated sites. However, the certain structure and stoichiometry of these colloids, as well as Pu oxidation states present is still debated. This contribution will show the results of actinide nanoparticles studies by complementary methods: X-ray diffraction (XRD), atomic pair distribution function analysis (PDF), several types of spectroscopies: high energy resolution fluorescence detection (HERFD) at L₃ and M₅-edges, X-ray emission spectroscopy (XES) and extended X-ray absorption fine structure (EXAFS) spectroscopy. The applying multifold synchrotron methods benefits to discover features, which may be unclear or even indistinguishable, these approach is also crucial to confirm results, obtained with individual methods. It was found that small (2 nm) nanoparticles are formed from the Pu (III), Pu (IV), Pu (V) aqueous solutions, with the crystal structure close to PuO₂, without any other Pu-O contributions or oxidation states of Pu except Pu (IV)

[en] Highlights: • The X-ray absorption spectra of actinides are discussed with an emphasis atomic multiplet theory, charge transfer theory and crystal field theory. • Resonant inelastic X-ray emission spectra (RIXS) reveal many new features in the X-ray absorption spectra of actinides. • The new range of RIXS beamlines will become an important tool in the determination of the electronic structure of actinides. - Abstract: The X-ray absorption spectra of actinides are discussed with an emphasis on the fundamental effects that influence their spectral shape, including atomic multiplet theory, charge transfer theory and crystal field theory. Many actinide spectra consist of a single peak and it is shown that the use of resonant inelastic X-ray emission spectra (RIXS) has the potential to reveal many new features in the X-ray absorption spectra of actinides. The new range of RIXS beamlines will allow the determination of new structures in the X-ray absorption spectra that have been hitherto invisible. This has the potential to become an important tool in the determination of the electronic structure of actinides

[en] The Tc retention by the iron(II)-containing minerals magnetite (Fe"I"IFe"I"I"I_2O_4) and siderite (Fe"I"ICO_3) was studied by means of batch sorption experiments as well as ATR FT-IR and XAS spectroscopy. The strong Tc retention could be attributed to surface-mediated reduction of Tc(VII) to Tc(IV).

[en] Optimising the properties of catalysts for industrial processes requires a detailed knowledge of their structure and properties on multiple length scales. Synchrotron light sources are ideal tools for characterising catalysts for industrial R and D, providing data with high temporal and spatial resolution, under realistic operating conditions, in a non-destructive way. Here, we describe the different synchrotron techniques that can be employed to gain a wealth of complementary information, and highlight recent developments that have allowed remarkable insight to be gained into working catalytic systems. These techniques have the potential to guide future industrial catalyst design. (authors)

[en] XAS spectra of U and Np sorption biogenic ferrihydrite samples were compared to abiotic samples. The k"3-weighted χ-spectrum and its Fourier-transform of the studied biogenic ferrihydrite sample bears close resemblance to the bidentate edge-sharing innersphere sorption "1E complex, which is the main sorption species on abiotic ferrihydrite. Based on the shell fit analysis, the distances of the coordination shells U-O_e_q, U-O_a_x, and U-Fe are similar to those determined for abiotic ferrihydrite samples.

[en] Here we provide evidence that the formation of PuO${}_2$ nanoparticles from oxidized Pu${}^{VI}$ under alkaline conditions proceeds through the formation of an intermediate PuV solid phase, similar to NH${}_4$PuO${}_2$CO${}_3$, which is stable over a period of several months. For the first time, state-of-the-art experiments at Pu M${}_4$ and at L${}_3$ absorption edges combined with theoretical calculations unambiguously allow to determine the oxidation state and the local structure of this intermediate phase. (© 2019 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)