[en] Uranium metal and the uranium oxides UO₂, U₃O₈, UO₃ are studied by photoelectron spectroscopy. Chemical shifts of the 4f electronic core levels are measured, and the valence bands recorded. These data are correlated with measurements of the half-life of²³⁵Usup(m) for the E3 isomeric transition by electron conversion. An attempt is made to explain the electronic structure in the valence region. (Auth.)

[en] The present outlook of electronic structural data for uranium and thorium oxides and fluorides is given on the basis of high resolution X-ray photoelectron spectra, including core levels chemical shifts, shake-up satellites and valence bands. E.P.R. data are included for identifying paramagnetic ions when possible. New results for U₄O₉ and preliminary data for mixed uranium oxides lead to increase the understanding of U4f chemical shifts. (author)

[en] The analysis of the shake-up satellites recorded in core-level photoelectron spectra of uranium oxides and fluorides is used to understand the electronic structure of the valence and conduction bands of the solids. This study is shown to support the view that U₃O₈ and U₂O₅ are made of U(IV) and U(VI) species comparable to those in UO₂ and UO₃. A model proposed for charge transfer in transition metal compounds is used, and an interpretation of these satellites is presented, that results in the location of the 6d conduction band of UO₂ at about 4 eV above the Fermi level of the sample. (Auth.)

[en] Uranium oxides UO₂, U₂O₅, U₃O₈ and UO₃ have been studied by X-ray photoemission (E.S.C.A.) and electron paramagnetic resonance. Binding energy values are reported for the U4f core levels, showing that U₂O₅ is UO₂. UO₃ and U₃O₈ is UO₂.2UO₃. Valence band structures are discussed in relation with the formation of (UO₂)²⁺ groups. Results from EPR spectroscopy support the view that no U(V) species are presented in these compounds. (Auth.)

[en] X-ray excited electron spectra from two uranium fluorides, UF₄ and K₂UF₆, are presented. The uranium-fluorine chemical bond is studied by comparison with previously reported ESCA measurements on uranium oxides and uranyl compounds. The spectrum of K₂UF₆ is shown to be composed of simple additive contributions from its preparation constituents, UF₄ and KF. (Auth.)

No abstract available

[en] The electrochemical reduction of uranium and neptunium ions is achieved in aprotic solvents in presence of acrylonitrile. The cathodic deposit on a usual metal consists of a grafted polyacrylonitrile layer in which actinide oxide or actinide metal has been inserted as a consequence of the overall cathodic reaction. As polyacrylonitrile is an insulating material, the electrochemical polymerization reaction is stopped when the polymer layer thickness reaches 1000 A at maximum. The material we thus produced may be used as an alpha spectroscopy source and we report here the results originating from the preparation of more than hundred samples. (orig.)