Hyperfine splittings and Zeeman infrared absorption ofTb3+-dopedCaF2and

Jon‐Paul R. Wells

¹

,

G. D. Jones

²

Abstract

We report on the observation of pseudoquadrupole splittings of sharp infrared-absorption lines of CaF 2 :Tb 3+ . These splittings are large enough to be directly observed because the Tb 3+ electronic ground levels consists of two singlets separated by only 0.18 cm −1 for the F − C 4v center. Both the hyperfine splittings and measured Zeeman splittings for F − C 4v centers in CaF 2 :Tb 3+ and SrF 2 :Tb 3+ can be accounted for using wave functions derived from a previously published crystal-field analysis of experimental energy levels.

Complete crystal field calculation of Zeeman-hyperfine splittings in europium

“…In true doublets such as the high symmetry (C 4v ) Pr 3+ :CaF 2 ground state [8], there is again a large first order magnetic dipole term. In pseudo-doublet ground states (two singlets split by only a few cm −1 ) such as those observed in Ho 3+ [7,15,21] or Tb 3+ [22,23], it is the second order magnetic dipole interaction, commonly referred to as the pseudo-quadrupole (see Section III B), that has the largest contribution. Provided the crystal field splitting of the pseudo-doublet ground state is accurately modeled, satisfactory fits to the hyperfine splittings of transitions can be achieved by calculating the magnetic dipole interaction, with the 4f quadrupole having only a minor effect on the splittings [15].…”

“…Sufficiently accurate splittings of these pseudodoublets can be achieved by the inclusion of the twoelectron correlation crystal field parameters [7], or by manual manipulation of the levels [21]. Hyperfine structure of non-Kramers doublets and pseudo-doublets has been successfully calculated in several hosts, including CaF 2 [7,8,15,23], SrF 2 [8,23], LiYF 4 [20,22], KY 3 F 10 [18], CaWO 4 [19], YAl 3 (BO 3 ) 4 [16], YPO 4 [17], and both sites of Y 2 SiO 5 [21].…”

“…An alternative is to use a full crystal field model for the whole 4f configuration of the rare earth ion, including interactions that generate hyperfine structure. These types of models have been successfully applied for several different hosts doped with Kramers and non-Kramers rare earth ions, including Pr 3+ [5,[7][8][9][10], Er 3+ [11][12][13][14], Ho 3+ [7,[15][16][17][18][19][20][21], Tb 3+ [22,23], and Tm 3+ [4,10]. However, a complete crystal field calculation of Eu 3+ Zeemanhyperfine structure has not been demonstrated.…”