نتایج جستجو برای: actinide
تعداد نتایج: 1114 فیلتر نتایج به سال:
In order to promote our understanding on electronic structure of actinide dioxides, we construct a tight-binding model composed of actinide 5f and oxygen 2p electrons, which is called f-p model. After the diagonalization of the f-p model, we compare the eigen-energies in the first Brillouin zone with the results of relativistic band-structure calculations. Here we emphasize a key role of f-p hy...
The first examples of actinide complexes incorporating corrole ligands are presented. Thorium(IV) and uranium(IV) macrocycles of Mes2(p-OMePh)corrole were synthesized via salt metathesis with the corresponding lithium corrole in remarkably high yields (93% and 83%, respectively). Characterization by single-crystal X-ray diffraction revealed both complexes to be dimeric, having two metal centers...
The relation between the quadrupole-octupole deformation and the structure of high-K isomers in heavy even-even nuclei is studied through a reflection asymmetric deformed shell model including a BCS procedure with constant pairing interaction. Two-quasiparticle states with Kπ = 4−, 5−, 6−, 6 and 7− are considered in the region of actinide nuclei (U, Pu and Cm) and rare-earth nuclei (Nd, Sm and ...
The chemistry of the actinide family is surprisingly rich. In order to better understand the affinity of specific chelates as in the case of ionic selective recognition or uptake by specific biomolecules, it is essential to better understand the intramolecular interactions. Although this has long been done for widely investigated transition metals, very few studies have been devoted to complexa...
Actinide single-molecule magnetism has experienced steady growth over the last five years since the first discovery of slow magnetic relaxation in the mononuclear complex U(Ph(2)BPz(2))(3). Given their large spin-orbit coupling and the radial extension of the 5f orbitals, the actinides are well-suited for the design of both mononuclear and exchange-coupled molecules, and indeed at least one new...
Uranium and plutonium's 5f electrons are tenuously poised between strongly bonding with ligand spd-states and residing close to the nucleus. The unusual properties of these elements and their compounds (e.g., the six different allotropes of elemental plutonium) are widely believed to depend on the related attributes of f-orbital occupancy and delocalization for which a quantitative measure is l...
Trinuclear, supramolecular wheel structures are formed spontaneously from the metallation of a Schiff-base-pyrrole macrocycle by Ce(3+) cations, while the related actinide U(3+) cation is instead oxidised to U(4+) and encapsulated by the macrocyclic framework.
Mixed actinide(III,IV) oxalates of the general formula M2.2UAn(C2O4)5·nH2O (An = Pu or Am and M = H3O(+) and N2H5(+)) have been quantitatively precipitated by oxalic precipitation in nitric acid medium (yield >99%). Thorough multiscale structural characterization using XRD and XAS measurements confirmed the existence of mixed actinide oxalate solid solutions. The XANES analysis confirmed that t...
The Time-dependent Hartree-Fock (TDHF) theory is applied to the study of heavy ion collisions at energies around the Coulomb barrier. The competition between fusion and nucleon transfer mechanisms is investigated. For intermediate mass systems such as O+Pb, proton transfer favors fusion by reducing the Coulomb repulsion. A comparison with sub-barrier transfer experimental data shows that pairin...
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