Effect of rf field on spin diffusion

A study was made of the effect of an rf field on spin diffusion. The interaction of spins with the rf field is described quantum mechanically. It is shown that the effect of the rf field on the system of spins can, in some approximation, be interpreted as the effect of a change in the Larmor frequency of the spin and a decrease in the magnitude of the dipole-dipole interaction between spins. These conclusions were obtained on the basis of a unitary transformation which eliminates the explicit form of the spin-photon interaction operator in the Hamiltonian of the system considered. An expression is derived for the spin-diffusion coefficient under saturation. The presence of the rf field results in a decrease in the diffusion coefficient.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 7–11, September, 1979.