Theory of ESR Spectrum of S=5/2 Ions with Large Fine Structure Constant

The analysis of the spin Hamiltonian D[(Sᴢ²-1/3S²)＋λ(Sx²-Sy²)]+g。µS•H+ S•A•I with S=5/2 is made for an arbitrary direction of an applied constant magnetic field H. A deviation of λ from 1/3 and g。µS• H are treated as a perturbation. Then S •A• I is treated as a perturbation to them. From these calculations, the effective g-factor, the transition probability and the hyperfine splitting are evaluated. These results are useful for the analysis of the ESR signal with g =4.29 observed in amorphous materials doped with transition metal ions with S =5/2. The method of the extension of the present calculation to more general values of S is also presented.