Absorption spectra analysis of hydrated uranium(III) complex chlorides

Absorption spectra of powdered samples of hydrated uranium(III) complex chl orides of the formulas NH4UCl4. 4H(2)O and CsUCl4. 3H(2)O have been recorde d at 4.2 K in the 4000-26 000 cm(-1) range. The analysis of the spectra ena bled the determination of crystal-field parameters and assignment of 83 and 77 crystal-field levels for the tetrahydrate and trihydrate, respectively. The energies of the levels were computed by applying a simplified angular overlap model as well as a semiempirical Hamiltonian representing the combi ned atomic and crystal-field interactions. Ab initio calculations have enab led the application of a simplified parameterization and the determination of the starting values of the AOM parameters. The received results have pro ved that the AOM approach can quite well predict both the structure of the ground multiplet and the positions of the crystal-held levels in the 17 000 -25 000 cm(-1) range, usually obscured by strong f-d bands. (C) 2000 Elsevi er Science B.V. All rights reserved.