Abstract: Based on the crystal-field theory, the high-order perturbation formulae of the EPR parameters g factors g‖,g⊥ and the hyperfine structure constants A‖,　A⊥ for a 4d7 ion in tetragonally compressed octahedra were established and applied to the EPR spectra for the Rh2+｛A｝ center in lithium deuteride. In the theoretical calculations, the contributions of the g factors from the cubic field parameter Dq and the tetragonal field parameters Ds　and Dt were taken into account. In addition, the contributions of the hyperfine structure constants from the core polarization constant and the reduction factor H due to the admixture between the 4d and 5s orbitals of the central ion were also included. The calculated results show good agreement with the experimental data. The corresponding parameters are Ds≈-313cm-1,Dt≈-52cm-1,H≈0.502, suggesting that the system studied has some tetragonal distortion and admixture of the 5s orbitals of the central ion.

Key words: LiD , Rh2+, crystal field theory, electron paramagnetic resonance (EPR)