Angular variation of normal-type EPR intensities of V2+ in CsMgCl3

Abstract

EPR measurements have been made at room temperatures on a trigonal V2+ centre in CsMgCl3 that was analysed as a substitutional centre by McPherson et al. to second-order in perturbation theory. The spectrum has been described by direct diagonalization of a 32*32-dimensional spin-Hamiltonian matrix using the computer software developed originally by the authors. The anisotropic parameters g/sub ///-gperpendicular to and b20 have opposite signs to each other contrary to the expectation from simple electrostatic theory. By rotating the sample while keeping the c-axis normal to the external magnetic field, signal intensities of low- and high-field fine-structure lines interchanged characteristically. From theoretical calculation the intensity variation has been ascribed to the variation of the transition probability. The intensity variation is considered to be the elementary process for the resonant field shift observed in magnetically concentrated materials. The uniaxial direction of a trigonal or tetragonal centre in a microwave cavity can be known from this type of intensity-variation measurement irrespective of the sign of the fine-structure parameter b20.