Energy Levels of U4+ in an Octahedral Crystalline Field

The electronic energy levels determined from absorption spectra of U4+ in crystals containing UCl62— complexes are identified as to irreducible representation and the resulting set of levels used to determine the least-squares best values of Slater Fk integrals, spin—orbit ζ5f, and fourth- and sixth-degree crystalline potential parameters A 〈r4〉 and B 〈r6〉. It was necessary to diagonalize within the 5f2 configuration all these interactions simultaneously. The values are F2=191.4,F4=33.83,F6=3.98,ζ5f=1796,A〈r4〉=912,B〈r6〉=56.5. New data on the spectra of the UBr62— complex are presented.