EFFECT OF OPTICAL-PUMPING IN THE MAGNETIZATION OF ATOMS WITH A HYPERFINE-STRUCTURE OF LEVELS

Light-induced magnetization of a gas containing active atoms with a hy perfine structure of levels is studied. In the performed calculations, we use the perturbation theory and assume that the central frequency of an ultrashort light pulse propagating through the gas is close to t he transition frequency omega(ba) = (E(b) - E(a))HBAR(-1), where E(a) and E(b) are the energies of the ground and excited atomic levels, res pectively, without allowance for hyperfine interaction. Two magnetizat ion mechanisms are revealed. The main mechanism of light-induced magne tization is associated with resonant interaction, which is responsible for the redistribution of atoms in a gas with respect to the projecti ons of the total momentum in resonant sublevels. Such redistribution e xerts a considerable influence on the magnetic moment of each atom, An other mechanism of light-induced magnetization is associated with opti cal pumping, which transfers atoms from the resonant sublevel of the g round state E(a) to all the sublevels of the same ground state allowed by the selection rule in the total momentum, as well as to the sublev els of a metastable state E(c) for atoms with Lambda-configuration of levels, E(a) < E(c) < E(b). The total light-induced magnetization is e qual to the sum of the contributions associated with resonant interact ion and optical pumping. Therefore, the total magnetization depends on the total momenta of atoms in all above-specified sublevels of hyperf ine structures. We revealed a peculiar hyperfine structure in the ligh t-induced magnetization of a gas, which is manifested when we scan the central frequency of the incident ultrashort light pulse. The conclus ions of our analysis are illustrated by specific examples of rubidium and indium atoms with a doublet splitting of the ground and excited st ates E(a) and E(b).