Analysis and computer simulation of high-Spin Fe 3+ powder EPR spectra with g iso approximately 30/7

Abstract

A method of simulating “ g′ = 4.3 ” powder spectra of high-spin Fe 3+ is presented. The method utilizes “exact” energy solutions to the spin Hamiltonian followed by powder simulation from an effective g “tensor.” The method is applicable to cases where the second degree fine structure energy is comparable in magnitude to the electronic Zeeman energy and any combination of fourth degree spin operators may be included. In the approximation that the spectra arise from sites of mmm ( D 2h ) or higher symmetry it is sometimes possible to use the method to refine spin-Hamiltonian parameters from powder spectra. Applicability to sites of lower than mmm Laue symmetry involves consideration of noncoaxial g and D principal directions and possible inclusion of “low symmetry” fourth degree operators in the spin Hamiltonian.