Semiclassical theory of spin relaxation in media with a high viscosity

Relaxation equations are obtained which describe the behavior of a spin system under the influence of a stochastic pertubation without the application of perturbation theory. A purely discontinuous process of rotational motion of molecules giving rise to spin relaxation is studied. The line profile of a two-spin system and electron spin resonance is calculated when there is anisoptropy of the $g$ factor and hyperfine splitting.