Neptunium carbonato complexes in aqueous solution; An Electrochemical, spectroscopic, and quantum chemical study

Ikeda, Atsushi; Tsushima, Satoru*; Takao, Koichiro*; Rossberg, A.*; Funke, H.*; Scheinost, A. C.*; Bernhard, G.*; Yaita, Tsuyoshi; Hennig, C.*

Inorganic Chemistry, 48(24), p.11779 - 11787, 2009/12

https://doi.org/10.1021/ic901838r

The electrochemical behavior and complex structure of Np carbonato complexes have been investigated in aqueous NaCO and NaCO/NaOH solutions at different oxidation states by using cyclic voltammetry, X-ray absorption spectroscopy, and density functional theory calculations. The end-member complexes of penta- and hexavalent Np in 1.5 M NaCO with pH = 11.7 have been determined as a transdioxo neptunyl tricarbonato complex, [NpO(CO)] ( = 5 for Np, and 4 for Np). In contrast, the electrochemical oxidation of Np in a highly basic carbonate solution of 2.0M NaCO/1.0M NaOH (pH 13) yielded a stable heptavalent Np complex of [Np O(OH)], indicating that the oxidation reaction from Np to Np in the carbonate solution involves a drastic structural rearrangement from the transdioxo configuration to a square-planar-tetraoxo configuration, as well as exchanging the coordinating anions from carbonate ions (CO) to hydroxide ions (OH).

Electrochemical and complexation behavior of neptunium in aqueous perchlorate and nitrate solutions

Ikeda, Atsushi; Hennig, C.*; Rossberg, A.*; Funke, H.*; Scheinost, A. C.*; Bernhard, G.*; Yaita, Tsuyoshi

Inorganic Chemistry, 47(18), p.8294 - 8305, 2008/09

https://doi.org/10.1021/ic8009095

Electrochemical and complexation properties of neptunium (Np) are investigated in aqueous perchlorate and nitrate solutions by means of cyclic voltammetry, bulk electrolysis, UV-visible absorption and Np L-edge X-ray absorption spectroscopies. The redox reactions of Np(III)/Np(IV) and Np(V)/Np(VI) couples are reversible or quasi-reversible, while the electrochemical reaction between Np(III/IV) and Np(V/VI) is irreversible because they undergo the structural rearrangement from spherical coordinating ions (Np and Np) to transdioxo neptunyl ions (NpO, n = 1 for Np(V) and 2 for Np(VI)). A detailed analysis on extended X-ray absorption fine structure (EXAFS) spectra suggests that Np(IV) forms a decaaquo complex of [Np(HO)] in 1.0 M HClO, while Np(V) and -(VI) exist dominantly as pentaaquo neptunyl complexes, [NpO(HO)] (n = 1 for Np(V) and 2 for Np(VI)).

Single pulse nm-size grating formation in polymers using laser ablation with an irradiation wavelength of 355nm

Lippert, T.*; Gerber, T.*; Wokaun, A.*; Funk, D. J.*; Fukumura, H.; Goto, Masahiro

Applied Physics Letters, 75(7), p.1018 - 1020, 1999/00

https://doi.org/10.1063/1.124584

no abstracts in English

International Standard Problem (ISP) No.41; Computer code comparison exercise based on a Radioiodine Test Facility (RTF) experiment on iodine behaviour in containment under severe accident conditions

Ball, J.*; Glowa, G.*; Wren, J.*; Rydl, A.*; Poletiko, C.*; Billarand, Y.*; Ewig, F.*; Funke, F.*; Hidaka, Akihide; Gauntt, R.*; et al.

NEA/CSNI/R(99)7, p.311 - 325, 1999/00

Effect of cascade remnants on freely migrating defects in Cu-1%Au alloys

Iwase, Akihiro; L.E.Rehn*; P.M.Baldo*; L.Funk*

Ion-Solid Interactions for Materials Modefication and Processing (Mater. Res. Soc. Symp. Proc., Vol. 396), 0, p.179 - 184, 1996/00

no abstracts in English

Intercascade annihilation of freely migrating defects

Iwase, Akihiro; L.E.Rehn*; P.M.Baldo*; L.Funk*

Applied Physics Letters, 67(2), p.229 - 231, 1995/07

https://doi.org/10.1063/1.114676

no abstracts in English