Publications by authors named "Hanna Oher"
The bond distance is the simplest and most obvious indicator of the nature of a given chemical bond. However, for rare chemistry, it may happen that it is not yet firmly established. In this communication, we will show that the formally-triple protactinium(V) mono-oxo bond is predicted to be longer than what was previously reported in the solid state and in solution, based on robust quantum mechanical calculations, supported by an extensive methodological study.
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- - The research explores how uranyl hydroxides interact with orthosilicic acid using both experimental and theoretical methods, specifically at varying pH levels (9.2, 10.5, and 11.5) and low concentrations of uranium.
- - Key techniques included spectroluminescence titration, UV-Vis spectrometry, and TRLFS, which were used to determine the formation constants of complexes like UO(OH)SiO(OH) and their behaviors at different pH values.
- - The findings have significant implications for understanding uranium speciation in environments rich in silicic acid and how it may be affected by competing carbonate, particularly in contexts relevant to nuclear waste disposal strategies.
Article Synopsis
- - Bent uranyl complexes formed with chloride and 1,10-phenanthroline ligands influence their crystal structures and absorption/emission properties, as shown through various spectroscopic techniques and quantum-chemical calculations.
- - The study utilized spin-orbit time-dependent density functional theory to analyze the behavior of bare uranyl complexes and their components, including simulations of their emission spectra.
- - Findings suggest that the bending of uranyl in these complexes leads to excitations in the uranyl bending mode, resulting in a more complex and denser luminescence spectrum during photoluminescence experiments.
Protactinium ( = 91) is a very rare actinide with peculiar physico-chemical properties. Indeed, although one may naively think that it behaves similarly to either thorium or uranium by its position in the periodic table, it may in fact follow its own rules. Because of the quite small energy gap between its valence shells (in particular the 5f and 6d ones) and also the strong influence of relativistic effects on its properties, it is actually a challenging element for theoretical chemists.
View Article and Find Full Text PDFUranyl binitrate complexes have a particular interest in the nuclear industry, especially in the reprocessing of spent nuclear fuel. The modified PUREX extraction process is designed to extract U(VI) in the form of UO(NO)(L) as has been confirmed by extended X-ray absorption fine structure (EXAFS), X-ray diffraction (XRD), and time-resolved laser-induced fluorescence spectroscopy (TRLFS) measurements. In this study, the L ligands are two molecules of ,-di-(ethyl-2-hexyl)isobutyramide (DEHiBA) monoamide used to bind uranyl in its first coordination sphere.
View Article and Find Full Text PDFThe luminescence spectra of triscarbonatouranyl complexes were determined by experimental and theoretical methods. Time-resolved laser-induced fluorescence spectroscopy was used to monitor spectra of uranyl and bicarbonate solutions at 0.1 mol kg ionic strength and pH 8.
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- - The study investigates the luminescence properties of the [UOCl] complex in an organic phase using time-resolved laser-induced fluorescence spectroscopy and advanced modeling techniques.
- - The luminescence spectrum is shaped by symmetrical vibrations and geometric changes, with theoretical predictions suggesting minimal influence from the second coordination sphere on spectral shape for similar first-coordination-sphere ligands.
- - Experimental findings align well with theoretical calculations, confirming the accuracy of predictions regarding the luminescence properties and structural changes in uranyl complexes.