The superhyperfine structure of a system exhibiting the dynamic Jahn-Teller effect: CaF2:Sc(2+)

The superhyperfine (S.H.F.) interaction between the ground vibronic doublet state of Sc(2+) and the nuclear spins of the eight nearest flourine (I = 1/2) neighbors in CaF2 has been studied by E.P.R. using large applied uniaxial stress. The analysis of the S.H.F. structure employs an effective Hamiltonian derived from group theory. The experimentally determined parameters are: alpha 1/g1beta = 1.62 + or - 0.1 Gause alpha 2/g 1 beta = 1.67 + or - 0.23 Gauss, q alpha 3/g 1 beta = 1.77 + or - 0.08 Gauss, q alpha 4/g 1 beta = 1.24 + or - 0.12 Gauss (g alpha 5/g 1 beta less than or equal to 0.58 Gauss. Neighboring nuclei spin flips were observed during E.P.R. transitions. Probabilities for all S.H.F. lines were predicted within experimental accuracy and computer reconstructions of the large stress S.H.F. spectra were made. L.C.A.O.:M.O. were used to obtain a crystal field Hamiltonian which was compared with the symmetry-determined Hamiltonian and the observed parameters. Agreements and discrepancies are discussed.