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Es wird über eine spezifische Abtrennung des Urans aus Mischungen radioaktiver Spaltprodukte mittels Dünnschichtchromatographie berichtet. Die bei kurz bestrahlten Uranproben am Uranfleck gefundene Radioaktivität kann auf Grund γ-spektrometrischer Messungen dem ²³⁹Np zugeordnet werden.     

Magnetic Properties of Np2Ir2In Investigated by 237Np Mössbauer Spectroscopy

The present study of Np₂Ir₂In completes the ²³⁷Np Mössbauer spectroscopy investigations of Np₂T₂X (T = Co, Rh, Ir, Ni, Pd, Pt; X = In, Sn) compounds. Np₂Ir₂In is found to order at T _ord30 K and the complex Mössbauer spectra suggest the occurrence of a noncollinear modulated magnetic structure with an average magnetic moment on the neptunium _Np0.76 _B. The magnetic properties of Np₂Ir₂In are consistent with the general trends observed in the An₂T₂X (An =U, Np) isostructural family.     

Die Anwendung der Methode der zeitlich korrelierten assoziierten Teilchen (MEZKAT)

The TCAPM was developed to absolute and precise fission cross section measurement for neutron energies from 2 MeV up to 19 MeV. Experimental results of absolute fission cross section measurements on ²³³U, ²³⁵U, ²³⁸U, -²³⁷Np, ²³⁹Pu and ²¹²Pu are given. Furthermore the TCAPM is suitable for the application of inelastic scattering of neutrons by the analysis of element contents.     

Actinide Organometallic Complexes with π-Ligands

Recent developments and results from the organometallic chemistry of the actinides are reviewed. In the last one and a half years the structural data of about 15 organometallic complexes of transuranium actinides (Np or Pu) have been published, all involving π-ligands in the coordination sphere of the metal ion. On the basis of these data, a comparison of these molecules is presented. Depending on the steric demands of the ligands, effects like the actinide contraction seem to be stronger or weaker in the structural features. This indicates that the interplay between the actinide ion and the π-ligand is rather flexible, enabling the formation of stable bonds over a broad range of actinide ion oxidation states.     

Photochemistry of f-element ions

Published data on photochemical reactions of f-element compounds, namely, uranyl ion and lanthanide and actinide ions, are surveyed and analyzed. The types of reactions of photoexcited ions, reaction mechanisms, and analytical applications of the photochemical methods for the separation, isolation, and determination of f-elements are considered.     

Thermal stability and degradation kinetic study of white and colored cotton fibers by thermogravimetric analysis

Complexation of neptunium(V) with fluoride in aqueous solutions at elevated temperatures was studied by spectrophotometry and microcalorimetry. Two successive complexes, NpO₂F(aq) and NpO₂F₂⁻, were identified by spectrophotometry in the temperature range of 10–70°C. Thermodynamic parameters, including the equilibrium constants and enthalpy of complexation between Np(V) and fluoride at 10–70°C were determined. Results show that the complexation of Np(V) with fluoride is endothermic and that the complexation is enhanced by the increase in temperature — a two-fold increase in the stability constants of NpO₂F(aq) and more than five-fold increase in the stability constants of NpO₂F₂⁻ as the temperature is increased from 10 to 70°C.     

The discoveries of uranium 237 and symmetric fission - from the archival papers of Nishina and Kimura

Shortly before the Second World War time, Nishina reported on a series of prominent nuclear physical and radiochemical studies in collaboration with Kimura. They artificially produced (231)Th, a member of the natural actinium series of nuclides, by bombarding thorium with fast neutrons. This resulted in the discovery of (237)U, a new isotope of uranium, by bombarding uranium with fast neutrons, and confirmed that (237)U disintegrates into element 93 with a mass number of 237. They also identified the isotopes of several middle-weighted elements produced by the symmetric fission of uranium. In this review article, the highlights of their work are briefly summarized along with some explanatory commentaries.     

Synthesis of Non-Aqueous Neptunium(III) Halide Solvates from NpO2

Two Np(III) halides, NpI₃(THF)₄ and NpBr₃(THF)₄, have been prepared and isolated in high yields as described in this work. Starting with neptunia (NpO₂), NpCl₄(DME)₂ was first generated in an updated, higher yielding synthesis than what was previously reported by using HCl/HF. This material was then reduced with KC₈, followed by subsequent ligand exchange, to generate NpBr₃(THF)₄ and NpI₃-(THF)₄. Full characterization by single-crystal X-ray crystallography, ¹H NMR spectroscopy and electronic absorption spectroscopy confirmed the molecular formulas and oxidation states. These trivalent materials are straightforward to synthesize and can be used as starting materials for non-aqueous Np(III) chemistry, obviating the need for rare and restricted Np metal and elemental halogens.