A simple model for the f-d transition of actinide and heavy lanthanide ions in crystals

The original simple model for 4f-5d transitions [C.K. Duan, M.F. Reid, G.W. Burdick, Phys. Rev. B 66 (2002) 155108; C.K. Duan, M.F. Reid, J. Solid State Chem. 171 (2003) 299], which assumes a stronger exchange Coulomb interaction between 4f orbitals and 5d orbitals than the 4f spin-orbit interaction, is extended to the case where the effect of the f (4f for heavy lanthanide and 5f for actinide ions) spin-orbit interaction is stronger than that of the exchange Coulomb interaction. The extended model is used to discuss the 4f-5d spectra of heavy lanthanide and actinide ions in crystals.