A5056785188- Radioactive element chemistry and processing
- Nuclear Materials and Properties
- Rare-earth and actinide compounds
- X-ray Spectroscopy and Fluorescence Analysis
- Radioactive contamination and transfer
- Nuclear Physics and Applications
- Geochemistry and Elemental Analysis
- Geochemistry and Geologic Mapping
- Lanthanide and Transition Metal Complexes
- Nuclear reactor physics and engineering
- Nuclear materials and radiation effects
- Geological and Geochemical Analysis
- Magnetism in coordination complexes
- Metallurgical Processes and Thermodynamics
- Organometallic Complex Synthesis and Catalysis
- Analytical chemistry methods development
- Electron and X-Ray Spectroscopy Techniques
- X-ray Diffraction in Crystallography
- Molten salt chemistry and electrochemical processes
- Advanced Materials Characterization Techniques
- Medical Imaging Techniques and Applications
- Ion-surface interactions and analysis
- Radiopharmaceutical Chemistry and Applications
- Boron Compounds in Chemistry
- Crystallization and Solubility Studies
Karlsruhe Institute of Technology
2019-2025
Lawrence Berkeley National Laboratory
2024-2025
Paul Scherrer Institute
2021
Joint Research Centre
2021
A detailed analysis is presented for the covalent character of orbitals in actinyls: UO22+, NpO22+, and PuO22+. Both initial, or ground state, GS, configuration excited configurations where a 3d electron into open valence, nominally 5f shell, are considered. The determined as fully relativistic, four component Dirac-Coulomb Hartree–Fock solutions. Several measures, which go beyond commonly used population analyses, to characterize an orbital order obtain reliable estimates covalency....
In actinide chemistry, the formal number of open‐shell 5f electrons, n(open), is a well‐defined quantity with an integer value. The effective occupation, n(f), additionally takes donation and back‐donation into account, generally has non‐integer value, varying numerical definitions. present study explores important distinction between n(f) n(open) in chemistry example PuO2, by using electronic structure methods relativistic Hamiltonian combination experimental Pu M5‐edge high energy...
The actinides possess a complex electronic structure, making their chemical and physical properties among the least understood in periodic table. Advanced spectroscopic tools, able to obtain deep insights into structure binding of actinides, are highly desirable. Here, we introduce two sensitive tools: one determines number localized 5f electrons on an actinide atom, another assesses covalent character actinide-ligand bonding. Both tools based multiplet present M4 edge core-to-core resonant...
Metal-reducing microorganisms such as Shewanella oneidensis MR-1 reduce highly soluble species of hexavalent uranyl (U(VI)) to less mobile tetravalent uranium (U(IV)) compounds. The biologically mediated immobilization U(VI) is being considered for the remediation U contamination. However, mechanistic underpinnings biological reduction remain unresolved. It has become clear that a first electron transfer occurs form pentavalent (U(V)) intermediates, but it not been definitively established...
Lanthanides are widely assumed not to form covalent bonds due the localized nature of their 4f valence electrons. This work demonstrates that ionic bond Sm(II) with cyclononatetraenyl (η
A detailed analysis of the wave functions for M
We applied relativistic multiconfigurational all-electron ab initio calculations including the spin–orbit interaction to calculate 3d4f resonant inelastic X-ray scattering (RIXS) map (3d3/2 → 5f5/2 U M4 absorption edge and 4f5/2 3d3/2 Mβ emission) of uranyl (UO22+). The calculated data are in excellent agreement with experimental results allow a detailed understanding observed features an unambiguous assignment all involved intermediate final states. energies corresponding maxima emission...
Plutonium is used as a major component of new-generation nuclear fuels and radioisotope batteries for Mars rovers, but it also an environmental pollutant. clearly has high technological importance, extremely complex, not well-understood electronic structure. The level covalency the Pu 5f valence orbitals their role in chemical bonding are still enigma thus at frontier research actinide science. We performed fully relativistic quantum computations structure Pu4+ ion PuO2 compound. Using four...
Over 60 years of nuclear activities have resulted in a global legacy radioactive wastes, with uranium considered key radionuclide both disposal and contaminated land scenarios. With the understanding that U has been incorporated into range iron (oxyhydr)oxides, these minerals may be secondary barrier to migration radionuclides environment. However, long-term stability U-incorporated (oxyhydr)oxides is largely unknown, end-fate species potentially impacted by biogeochemical processes. In...
The role of Fe in the increased stability uranyl( v ) is clarified by using state art uranium metalorganic chemistry, advanced X-ray spectroscopic approaches and computations.
We show that the structural and electronic properties of UO<sub>2</sub>NPs (2–3 nm) are similar to those bulk UO<sub>2</sub>under inert conditions, with U(<sc>iv</sc>) as dominating oxidation state, though NPs oxidize time under X-ray beam.
We report here the first synthesis of mixed oxide U1-xPuxO2(+y) nanoparticles. The obtained nanopowders were characterized by X-ray diffraction, thermal ionization mass spectrometry, transmission electron microscopy, Raman spectroscopy, and U M4 edge high-energy-resolution absorption near structure (HR-XANES). HR-XANES spectra give evidence for partial oxidation UIV to UV. This novel route toward formation actinide–actinide solid solution opens research opportunities that are not accessible...
Theoretical analyses of actinyls are necessary in order to understand and correctly interpret the chemical physical properties these molecules. Here, wave functions Uranyl, UO
U(IV) mobility can be significantly enhanced by colloids in both engineered and natural environments. This is particularly relevant decommissioning clean-up of nuclear facilities, such as legacy fuel ponds silos at the Sellafield site, UK, long-term radioactive waste geodisposal. In this study, product metallic uranium (U) corrosion under anaerobic, alkaline conditions was characterised, interaction with silicate solutions investigated. The U metal consisted crystalline UO2 nanoparticles...
The recently emerged actinide (An) M4,5-edge high-energy resolution X-ray absorption near-edge structure (HR-XANES) technique has proven to be very powerful for oxidation state studies of actinides. In this work, the first time, Np M5-edge HR-XANES was applied study sorption on illite. By improving experimental conditions, notably by operation spectrometer under He atmosphere, it possible measure spectra a sample with ≈ 1 μg Np/g illite (1 ppm). This is 30-2000 times lower than loadings...
In the Molten Salt Reactor (MSR) concept, metal fluorides are key components of possible fuel and coolant salts. The fast reactor option opens possibility for alternatives to Li based matrix salts, avoiding costly 7Li enrichment tritium production from residual 6Li. Such can be on NaF KF as components. this study, two pseudo-binary phase diagrams NaF-UF4 KF-UF4, NaF-KF-UF4 pseudo-ternary system were experimentally investigated using Differential Scanning Calorimetry (DSC). obtained data used...
In this study, Np(V) retention on Illite du Puy (IdP) was investigated since it is essential for understanding the migration behavior of Np in argillaceous environments. The presence structural Fe(III) and Fe(II) IdP confirmed by Fe K-edge X-ray absorption near-edge structure (XANES) 57Fe Mössbauer spectroscopy. batch sorption experiments, a higher affinity to found than Wyoming smectite or iron-free synthetic montmorillonite. An increase relative Np(IV) ratio sorbed onto with decreasing pH...
In this study, proton-irradiated tungsten targets, up to 2.6 GeV, were investigated for the purpose of experimental cross-section measurements. Radiochemical separation methods applied isolate residual long-lived alpha-emitters 148Gd, 154Dy, and 146Sm beta-emitters 129I 36Cl from targets. The molecular plating technique has been prepare samples alpha-spectrometry. Production cross-sections determined by means accelerator mass spectrometry. results are compared with theoretical predictions,...
A holder has been developed that enables electron yield-detected soft X-ray spectroscopy of fully contained samples at low temperature. Crucially, this design uses elements the sample containment to collect ejected electrons, removing need expose directly vacuum environment spectrometer. The is modular and should be adaptable a number different endstation configurations, enabling air-sensitive, radioactive vacuum-sensitive (biological) samples.
The ACT experimental station of the CAT-ACT wiggler beamline at Karlsruhe Institute Technology (KIT) Light Source is dedicated to investigation radionuclide materials with radioactivities up 1000000 times exemption limit by various speciation techniques applying monochromatic X-rays. In this article, latest technological developments that enable high-resolution X-ray absorption near-edge structure (HR-XANES) spectroscopy for low loading samples are highlighted - encompassing actinide...
Targeted alpha therapy (TαT) represents an emerging and cutting-edge treatment option for patients dealing with highly challenging metastatic cancer diseases. Critically, the limited supply of alpha-particle-emitting radionuclides, so-called in vivo nanogenerators, hampers wider utilization TαT clinical settings. This could effectively be circumvented by alternative production routes, including straightforward purification reformulation strategies. Radionuclide generators offering great...