Study of the vibronic effects from the Zeeman-field-induced Mössbauer spectra ofFe2+ions in octahedral symmetry. I. The effective Hamiltonian formalism

Abstract

The importance of the Zeeman-field-induced quadrupole and hyperfine interactions in Jahn-Teller active ions is demonstrated with particular reference to ${\mathrm{Fe}}^{2+}$ in octahedral crystals such as CaO and KMg${\mathrm{F}}_{3}$. An effective electron nuclear Hamiltonian is derived from general symmetry principles, whose parameters are calculated by perturbation procedure, incorporating the vibronic effects in terms of Ham reduction factors between spin-orbit states. Relevant theoretical expressions for the M\ossbauer transitions are given so that these parameters can be determined experimentally from the analysis of the M\ossbauer spectra.