Energy-Level Scheme for Nd3+ in LiYF4

Abstract

Crystal-field parameters appropriate for S4 symmetry were fit to existing data on the I49/2 and I411/2 sublevel splittings of LiYF4:Nd3+. Intermediate coupling wavefunctions obtained previously from fits to the CaWO4:Nd3+ spectrum were used. Although ground-state EPR data were not available in this system, the symmetries of the levels were uniquely assignable from group-theoretical considerations and the available polarization data. The parameter values found are (in cm−1): B02 = 482.7, B04 = − 1452.5, B06 = − 122.1, B44 = − 1222.0, B46 = − 981.9, B4′4 = − 0.3, and B4′6 = − 0.2. The rms deviation of this fit was 10. We calculate ground-state g∥ and g⊥ values of 0.483 and 2.571, respectively. The crystal-field parameters found here are compared with those of CaWO4:Nd3+ and those of the “mirror” ion Er3+ in LiYF4:Er3+. We conclude that simple geometrical considerations as to the algebraic signs of the crystal-field components in these systems may be misleading.