Electronic Structure of Ni2+ in MgF2 and ZnF2

Publisher Website
Google Scholar
Abstract
The absorption spectra of nickel (II) in MgF2 and ZnF2 are reported. The important feature of the spectra is that the first spin‐allowed absorption band shows strongly polarized line structure. From its polarization, the mechanism of the absorption for this line structure has been determined to be magnetic dipole. Furthermore, together with its temperature dependence, symmetry assignments have been made for the fine structure of 3T2 and the ground state. The energy separations and assignments of the ground state thus determined are compatible with the results of electron spin resonance. Choosing two parameters of the orthorhombic field so as to fit the energy separations of the ground state, each energy level of 3T2 under the combined action of the spin orbit force and orthorhombic fields has been calculated as a function of two remaining parameters and compared with experiment. The values of the four parameters and the discrepancy with experiment are discussed. It is shown that the effective Hamiltonian approach for 3T2 is as good as the configuration interaction approach including all the states of d8 electron configuration, provided the second‐order effect of the spin—orbit interaction is included. As one of possible mechanisms to remove the discrepancy with experiment within the framework of the crystal field theory, Jahn—Teller distortions of the 3T2 state are considered.