ELECTRON-SPIN-RESONANCE OF DIPOLE-COUPLED ANISOTROPIC PAIRS IN DISORDERED-SYSTEMS - SECULAR APPROXIMATION FOR POINT DIPOLES

ESR spectra of pairs of paramagnetic centers with anisotropic g tensors are considered. The centers are assumed to be point magnetic dipoles with effective spins f. The dipole coupling Hamiltonian is discussed, Powder spectra are numerically calculated in the secular approximation for the dipole splitting. The temperature dependence of the spectral lineshape due to spin polarization is also studied, Special attention is paid to pairs containing an unobservable partner with g(perpendicular to) = O. (C) 1995 Academic Press, Inc.