COMPARISON OF THE ELECTRONIC-STRUCTURE OF THE LANTHANIDES AND ACTINIDES

This paper reviews the electronic structure of the 4f and 5f compounds. To this end optical and magnetic analyses of similar compounds are compared. In most cases this entails comparing trivalent actinide with trivalent lanthanide compounds although the f(1) configuration (Ce3+ diluted in Cs2NaYCl6 and Pa4+ diluted in Cs2ZrCl6) is treated in detail. In general the ground electronic states for lanthanide and actinide compounds with the same number n of f electrons (f(n)) and the same coordination about the metal ions are similar, although the total crystal field splitting in the actinides is approximately twice as great as for the lanthanides. The half-filled shell f(7) is a special case with a relatively large ground state splitting in the 5f(7) ground term caused by the effects of the much larger spin-orbit coupling.