To the theory of the nuclear spin diffusion induced by a paramagnetic impurity in a diamagnetic crystal

The diffusion of nuclear magnetization inside a diffusion barrier, due to modulation of the fluctuation spin operator of a magnetic ion by the interaction between nuclei, is treated to third order of perturbation theory. Cross-relaxation transitions of two types are being modulated. These are the transitions in which a pair of nuclei is mutually reoriented either due to a dipole-dipole interaction between them or by the coupling of each nucleus to the electron spin. The relative effectiveness of these processes depends on the experimental conditions