Electronic structure of actinide compounds from<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">L</mml:mi></mml:mrow><mml:mrow><mml:mi mathvariant="normal">III</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math>-edge x-ray absorption

Bertram, S.; Kaindl, G.; Jové, J.; Pagès, M.; Gál, J.

doi:10.1103/physrevlett.63.2680

Cited by 42 publications

(40 citation statements)

References 12 publications

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“…The XANES of the U samples show only subtle changes as the U loadings increase, but suggest formation of a uranyl surface complex at low loadings and of a mixed oxidation state oxide at high loadings (Moyes et al, 2000). The XANES of all three Np samples indicate that Np(IV) is present (Bertram et al, 1989;Moyes et al, 2002).…”

Section: Resultsmentioning

confidence: 90%

X-ray absorption spectroscopy studies of reactions of technetium, uranium and neptunium with mackinawite

Livens

Jones

Hynes

et al. 2004

Journal of Environmental Radioactivity

108

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Section: Resultsmentioning

confidence: 90%

X-ray absorption spectroscopy studies of reactions of technetium, uranium and neptunium with mackinawite

Livens

Jones

Hynes

et al. 2004

Journal of Environmental Radioactivity

108

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“…The L III absorption edge in the actinides arises from the formally allowed 2p f 6d electronic transitions, and the XANES region for the lower oxidation state actinide ions (An(III), An(IV)) is characterized by a single, intense white line while that for actinyl ions such as NpO2 + typically displays a much less intense absorption peak (28)(29)(30). (30), although the direction of the shift (to higher energy for a lower oxidation state) is at first sight puzzling. However, this is an artifact arising from the way in which we define the edge position since the coordination environment of the neptunium center changes substantially on reduction and the shape of the edge also changes.…”

Section: Resultsmentioning

confidence: 99%

An X-ray Absorption Spectroscopy Study of Neptunium(V) Reactions with Mackinawite (FeS)

Moyes

Jones

Reed

et al. 2001

Environ. Sci. Technol.

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Neptunium is a transuranium element, produced in tonne quantities in nuclear reactors. Because it has access to a range of oxidation states, neptunium may undergo redox transformations in the environment and these can have far-reaching effects on its environmental mobility. Here, the reaction of NpO2+ (the soluble and thermodynamically stable neptunium species in oxic systems) with microcrystalline mackinawite is studied. Uptake of neptunium from solution is relatively low (approximately 10% of the total initially present in solution) and independent of initial solution concentration over the range 0.27-2.74 mM and of equilibration time. X-ray absorption spectroscopy (XAS) of the solid sulfide samples indicates nearest neighbor oxygen atoms at distances around 2.25-2.26 A, sulfur atoms at around 2.61-2.64 A, and two more distant shells fitted with iron, at 3.91-3.95 A and 4.15-4.16 A. These observations suggest that on interaction with the sulfide surface reduction of Np(V) to Np(IV) occurs, accompanied by loss of axial oxygen atoms. Neptunium coordinates directly to surface sulfide atoms, in contrast to the behavior previously observed for uranium under similar conditions. These results demonstrate the importance and variability of the speciation of redox sensitive actinides under anoxic conditions.

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“…The XANES spectrum of Np(IV)-AHA shows the characteristic near-edge features of tetravalent Np compounds [14,15,32,33]. The white line (WL) peak in the Np(IV) spectrum is more intense than in the spectrum of Np(V) which shows an additional shoulder on the high energy side of the WL.…”

Section: Xanes Spectramentioning

confidence: 97%

Neptunium(IV) complexation by humic substances studied by X-ray absorption fine structure spectroscopy

Schmeide¹,

Reich²,

Sachs³

et al. 2005

Radiochimica Acta

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Neptunium / Tetravalent / Humic acid / Structure / XANES / EXAFSSummary. We studied the coordination environment of neptunium(IV) in complexes with various natural and synthetic humic and fulvic acids at pH 1 by X-ray absorption fine structure (XAFS) spectroscopy. The results were compared to those obtained for the interaction of neptunium(IV) with Bio-Rex70, a cation exchange resin having solely carboxylic groups as metal binding functional groups. In both neptunium humate complexes and neptunium Bio-Rex70 sorbates, Np 4+ is surrounded by about 10 oxygen atoms at an average distance of 2.36 ± 0.02 Å. This verifies that the carboxylic groups are the main complexing sites of the humic substances responsible for binding neptunium(IV) in the acidic pH range. The data suggest a predominant monodentate coordination of the carboxylate groups to neptunium(IV) ions.

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Electronic structure of actinide compounds fromLIII-edge x-ray absorption

Cited by 42 publications

References 12 publications

X-ray absorption spectroscopy studies of reactions of technetium, uranium and neptunium with mackinawite

X-ray absorption spectroscopy studies of reactions of technetium, uranium and neptunium with mackinawite

An X-ray Absorption Spectroscopy Study of Neptunium(V) Reactions with Mackinawite (FeS)

Neptunium(IV) complexation by humic substances studied by X-ray absorption fine structure spectroscopy

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