Ground configuration splitting in UCl₅

Abstract

The absorption spectra of UCl 5 single crystal were observed in the region between 0.6 and 2.4 μm at room, 77, and 4.2 K temperatures. Five pure electronic transitions were assigned at 11 665, 9772, 8950, 6643, and 4300 cm −1 . The energy levels associated with these transitions were identified as the splittings of the 5f 1 ground configuration under the influence of the spin–orbit coupling and a crystal field of C 2v symmetry. The number of crystal field parameters was reduced by assuming the point-charge model where the positions of the ions were determined by X-ray crystallography. Then, the crystal field parameters and the spin–orbit coupling constant were calculated to be [Formula: see text],[Formula: see text], [Formula: see text], and ξ = 1760 cm −1 . The vibronic analysis showed that the 90, 200, and 320 cm −1 modes were similar to the T 2u (v 6 ), T 1u (v 4 ), and T 1u (v 3 ) of an UCl 6 − octahedron, respectively.