ANALYSIS OF THE CRYSTAL-FIELD SPECTRA OF THE ACTINIDE TETRAFLUORIDES .1. UF4, NPF4, AND PUF4

An interpretation of the low-temperature absorption spectra of AnF4 (An = U, Np, Pu) is presented. Using an effective operator Hamiltonian with orthogonalized free-ion operators and initializing crystal-field parameter values based on a superposition model calculation for An4+ sites with C2 symmetry, good agreement between the model calculations and experimentally observed absorption band structure could be obtained. Correlations with published magnetic and heat capacity measurements are discussed.