The Rossendorf Beam Line ROBL – a dedicated experimental station for XAFS measurements of actinides and other radionuclides

Reich, Tobias; Bernhard, Gert; Geipel, Gerhard; Funke, H.; Hennig, Christoph; Roßberg, André; Matz, W.; Schell, Norbert; Nitsche, H.

doi:10.1524/ract.2000.88.9-11.633

Cited by 98 publications

(109 citation statements)

References 9 publications

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“…The position and intensity of the peaks in the Fourier transform are related to the atomic identity, distance, and number of atoms in each shell. Thus, XANES is sensitive to the bond angles the solvating H 2 O adopt 10,31 and contains inset tables with the root-meansquare error (RMSE) within different spectral regions. In the case of U(IV), the nona-aqua species has the best agreement with the edge of the white line; however, the octa-aqua species has the least error in the peak position and height, and in the high-energy feature.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Sensitivity of Solvation Environment to Oxidation State and Position in the Early Actinide Period

et al. 2015

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The aqueous solvation of U-Pu in the III-VI oxidation states has been examined using density functional theory and hydrated cluster models of the form An(H2O)30(4+/3+) and AnO2(H2O)30(2+/+) embedded within a polarizable continuum model to approximate the effect of bulk water. The structural features are compared to available data from extended X-ray absorption fine structure. Then, using a multiple-scattering approach, the X-ray absorption near-edge spectra (XANES) have been simulated and compared to experiment. These structural data are complemented by a detailed thermodynamic analysis using a recently benchmarked protocol. The structural, spectroscopic, and thermodynamic information has been used to assign the primary solvation environments in water, with an emphasis upon understanding how oxidation state and position in the period modifies the hydration number and equilibrium between different solvation shell environments. Tetravalent U is proposed to exist in equilibrium between the 8- and 9-coordinate species. Moving to the right of the period, Np(IV) and Pu(IV) exist solely as the octa-aquo species. Reduction to the trivalent ions leads to thermodynamic favorability for this solvation environment, whose features reproduce the XANES spectra. The actinyl dications (AnO2(2+)) of U and Np have a preferred environment in the equatorial plane consisting of 5 solvating waters; however, changes to the ionic radius and electronic structure at Pu leads to an equilibrium between the 4- and 5-coordinate species for PuO2(2+). Reduction of the dications to form the monocations generally leads to a preference for the 4-coordinate primary solvation shell, with an equilibrium existing for uranyl, while the neptunyl and plutonyl species exist solely as AnO2(H2O)4(+). These data provide accurate thermodynamic information for several rare species and the combined thermodynamic, structural, and spectroscopic approach reveals trends in hydration behavior across actinide oxidation states and within the early actinide period.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Sensitivity of Solvation Environment to Oxidation State and Position in the Early Actinide Period

et al. 2015

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“…Uranium L III -edge EXAFS spectra were recorded in fluorescence mode at the Rossendorf Beamline (ROBL) [33] at the European Synchrotron Radiation Facility (ESRF) in Grenoble, France, using a Si(111) double-crystal monochromator. The fluorescence spectra were collected at room temperature with a four-pixel germanium solid-state detector.…”

Section: Exafs Measurements and Analysismentioning

confidence: 99%

Structural characterization of U(VI) surface complexes on kaolinite in the presence of humic acid using EXAFS spectroscopy

Křepelová

Reich

Sachs

et al. 2008

Journal of Colloid and Interface Science

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“…In the first case, the Np atom is surrounded by 2 axial oxygen atoms at 1.82 Å and 4 equatorial oxygen atoms at 2.21 Å [94] and in the second case by 2 axial oxygen atoms at 1.75 Å and 5 equatorial oxygen atoms at 2.41 Å . [60] Both L III edge spectra are compared in Figure 5 (a). From acidic to basic, they exhibit in one hand a broadening of WL A and on the other hand a shift to lower energy (Ϫ1 Ϯ 0.5 eV for the inflexion point; Ϫ0.7 Ϯ 0.2 eV for the WL maximum).…”

Section: Actinide Xanes and Electronic Structurementioning

confidence: 99%

“…Recently, a few groups have provided a much more complete characterization of Np VII complexes, both in the solid state and alkaline solution. [91,94,115Ϫ117] In the solid state, current XAFS [91] and single-crystal diffraction studies support the original Russian results, finding the tetraoxo configuration in the highly alkaline solutions (Ͼ 4  OH Ϫ ) that stabilize this Ϫ d [99] Ϫ e,i [103] Ϫ f [104] Ϫ g [67] Ϫ h [105] Ϫ j [106] Ϫ k [107] Ϫ l [108] Ϫ # this work (#1 in 0.1  HClO 4 ; #2 in 0.1  HNO 3 ); (b) neptunium: the horizontal line represents the border between the Np V /Np VI domains: m [109] Ϫ n [105] Ϫ o,q [60] Ϫ p [110] Ϫ r [94] Ϫ # this work (0.01  in HClO 4 ); (c) plutonium: the horizontal line represents the border between the Pu V /Pu VI domains; s,u [111] Ϫ t,v [42] high oxidation state and in crystals of Co(NH 3 ) 6 NpO 4 (OH) 2 ·2H 2 O grown from this medium. In this compound, the four NpϭO oxo bonds expand to 1.85Ϫ1.90 Å , ca.…”

Section: Aqueous Actinyl Cationsmentioning

confidence: 99%

Investigating Actinyl Oxo Cations by X‐ray Absorption Spectroscopy

et al. 2003

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Early actinide elements (from U to Am) have the ability to form linear trans-dioxo complexes with formal valence of the actinide being equal to (V) or (VI). For instance, the ubiquity of the uranyl cation in uranium aqueous chemistry is the basis for its very important industrial and environmental concerns. As a result, the physical chemistry of the actinyl moieties has been the subject of constantly growing investigations. Among all the spectroscopic probes, X-ray absorption spectroscopy is a particularly useful element and energy-selective technique. This article reviews the investigation of molecular actinyl complexes using both XANES and EXAFS tools. The absorption edge features have long been used to characterize the frontier orbitals of the absorbing atom. In the case of actinide cations, the L III edge, located in the hard X-ray region, provides a useful fingerprint of the cation polyhedron. Tentatively, simple molecular orbital considerations together with full multiple scattering simulation codes have MICROREVIEWS: This feature introduces the readers to the author's research through a concise overview of the selected topic. Reference to important work from others in the field is included. Complementary structural data can be obtained in the EXAFS region of the absorption spectrum. In the literature, such molecular systems have been well documented from uranyl aqueous chemistry to neptunyl or plutonyl coordination complexes with oxygen donor ligands. Furthermore, complexation mechanisms upon absorption onto mineral surfaces have been increasingly investigated over the past few years. Overall, contribution of the XAS technique to a better understanding of the actinide bonding is demonstrated from various examples of the literature and the authors' data. Importance of the simulation codes in order to better describe the absorption features is also strongly underlined.

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The Rossendorf Beam Line ROBL – a dedicated experimental station for XAFS measurements of actinides and other radionuclides

Cited by 98 publications

References 9 publications

Sensitivity of Solvation Environment to Oxidation State and Position in the Early Actinide Period

Sensitivity of Solvation Environment to Oxidation State and Position in the Early Actinide Period

Structural characterization of U(VI) surface complexes on kaolinite in the presence of humic acid using EXAFS spectroscopy

Investigating Actinyl Oxo Cations by X‐ray Absorption Spectroscopy

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