[en] The use of diketone ligands, such as hexafluoroacetylacetone (Hhfac) and tetramethylheptandione (Htmhd), can react in solvent-free and solvent-minimal routes to effect separation fission products from uranium matrices without any pre-preparation of the isotopes in question, and provides a path to drastically simplify the separations process and limits the potential for contamination and waste formation due to extensive handling, while increasing the rapidity of separation and isolation of target elements. In particular, the reactivity cesium, barium, strontium, silver, and lead with Hhfac can allow for rapid separations from uranium matrices such as oxide mixtures, in some cases in a matter of minutes. (author)

[en] The speciation of Tc(VII) in 12 M sulfuric acid was studied by NMR, UV-visible and XAFS spectroscopy, experimental results were supported by DFT calculation and were in agreement with the formation of TcO₃OH(H₂O)₂. In summary, the speciation of heptvalent technetium has been investigated in sulfuric acid. In 12 M H₂SO₄, a yellow solution is observed, and its ⁹⁹Tc NMR spectrum is consistent with a heptavalent complex. The yellow solution was further characterized by EXAFS spectroscopy, and results are consistent with the formation of TcO₃(OH)(H₂O)₂. No technetium heptoxide or sulfato- complexes were detected in these conditions. The molecular structure of TcO₃(OH)(H₂O)₂ has been optimized by DFT techniques, and the structural parameters are well in accordance with those found by XAFS spectroscopy. The experimental electronic spectra exhibit ligand-to-metal charge transfer transitions that have been assigned using TDDFT methods. Calculations demonstrate the theoretical electronic spectrum of TcO₃(OH)(H₂O)₂ to be in very good agreement with the experimental one. Recent experiments in 12 M H₂SO₄ show the yellow solution to be very reactive in presence of reducing agents presumably forming low valent Tc species. Current spectroscopic works focus on the speciation of these species.