s'authentifier
version française rss feed
HAL : jpa-00210822, version 1

Fiche détaillée  Récupérer au format
Journal de Physique 49, 8 (1988) 1425-1434
Analysis of the absorption and emission spectra of U4+ in α-ThBr 4
E. Simoni1, S. Hubert1, M. Genet1
(1988)

The low temperature form α-ThBr4 has a scheelite structure I41/a in which the tetravalent uranium occupies the thorium site which is S4. Assuming that the ground state remains Γ 4 as in the β-ThBr4 form, the polarized absorption spectrum at 4.2 K shows that D2d is a good approximation. A peculiarity of this host is the exaltation of very numerous fluorescences of U4+ which permit to assign four Stark levels of the ground state 3H4 : Γ5 at 110 cm-1, Γ 1 at 473 cm-1, Γ1 at 623 cm-1 and Γ5 at 830 cm-1. 30 levels have been assigned and the crystal field parameters of U4+ (5f2) have been calculated in the D2d approximation : B20 = - 382, B40 = - 3 262, B44 = - 1734, B60 = - 851 and B64 = - 1828 cm-1. It is interesting to note that a small distortion in the scheelite structure of the α-ThBr4 compared with the zircon structure β-ThBr4 induces important changes in the crystal field parameters.
1 :  IPNO - Institut de Physique Nucléaire d'Orsay
Physique/Articles anciens

Physique/Physique/Chimie-Physique
crystal field interactions – fluorescence – impurity and defect absorption spectra of inorganic solids – luminescence of inorganic solids – thorium compounds – uranium
Liste des fichiers attachés à ce document : 
PDF
ajp-jphys_1988_49_8_1425_0.pdf(1.3 MB)