t is pointed out that hyperfine interaction should be taken into account in the equation for the spin density matrix, which describes the evolution of atom polarization in optically pumped gases. A dispersion equation is derived for the possible frequencies of atom polarization oscillations in a polarized gas. It is shown that the very possibility of observation of paramagnetic resonance exchange line shifts is due to the presence of hyperfine interaction. An analysis is made of the dependence of the paramagnetic resonance excitation amplitude at frequencies involving an exchange shift of the relation between the energy of hyperfine interaction between the electron and nucleus and the exchange interaction energy.
V.G. Baryshevskii (Mon,) studied this question.