Pages: 1-9

Authors: Yury A. Teterin, Konstantin I. Maslakov, Mikhail V. Ryzhkov, Anton Yu. Teterin,
Kirill E. Ivanov, Stepan N. Kalmykov, Vladimir G. Petrov, and Dmitry N. Suglobov

Abstract

On the basis of the X-ray photoelectron spectroscopy data and results of theoretical calculations for the Cs₂NpO₂Cl₄^2- (D4h) cluster, the electronic structure and the chemical bond nature in Cs₂NpO₂Cl₄ single crystal, containing the neptunyl group NpO₂²⁺, was done in the binding energy range of 0 eV to ~35 eV. The filled Np 5f electronic states were established to form in the valence band of Cs₂NpO₂Cl₄. This was attributed to the direct participation of the Np  5f  electrons  in  the  chemical  bonding.  The  Np  6p  electrons were shown to participate in  formation  of  both  the  inner  valence  band  (~15 eV-~35 eV)  and  the outer valence band (0 eV-~15 eV). The filled Np 6p and the O 2s, Cl 3s electronic shells were found to make the largest contribution to the formation of the inner valence molecular orbitals. The molecular orbitals composition and the sequence order in the binding energy range 0 eV-~35 eV in Cs₂NpO₂Cl₄, were established. For the first time the quantitative scheme of molecular orbitals for the NpO₂Cl₄^2- cluster in the binding energy range 0 eV-~35 eV, was built. This scheme reflects neptunium close environment in the studied compound and is fundamental for both understanding the chemical bond nature in Cs₂NpO₂Cl₄ and the interpretation of other X-ray spectra of Cs₂NpO₂Cl₄. The contributions to the chemical binding for the NpO₂Cl₄^2- cluster were evaluated to be: the outer valence molecular orbitals contribution – 73 %, and the inner valence molecular orbitals contribution – 27 %.

Key words: actinide, neptunium, electronic structure, XPS, relativistic calculation

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