Abstract
The absorption spectra of U (III) in fused LiCl, KCl, and CsCl were measured in the spectrum range from 30000 to 7000 cm−1 at various temperatures between 700° and 890°C.
The visible and near infrared spectra of U (III) in these solutions depend largely upon the solvent cations radius and it is considered that this variation is due to the difference in the co-ordination structure of U (III) in each solution. The co-ordination structures of U (III) are attempted to infer from the following investigations; (i) the significant differences in the chemical properties of fused LiCl, KCl, and CsCl, (ii) the similarity of the chemical properties of the co-ordination structures of U (III) with those of Pu (III) and Am (III) having the known co-ordination structures, and (iii) a comparative tendency of the systematic dfference in the absorption spectra of U (IV) in solid state and fused alkali chlorides with that of U (III). It is assumed, consequently, that U (III) in fused CsCl and KCl media are co-ordinated with six chloride ions, and in fused LiCl, the coexistence of two species of U (III) co-ordinated with six chloride ions or less is reasonable.
