Isotopic selectivity of the optical pumping of atoms by frequency-controlled laser radiation

Schemes are proposed for isotopically selective optical pumping of atoms to aligned states which have a definite projection of the total angular momentum. A mixture of two atomic isotopes with isotopic shifts of the absorption lines less than the hyperfine-structure splitting is considered. Simultaneous optical pumping of these isotopes to states with opposite projections of the total angular momentum makes it possible to separate efficiently the isotopes over the different magnetic hyperfine-structure states. It is shown that the isotopic selectivity of frequency-controlled optical pumping can be S = 10¹⁰ — 10¹⁸ for the atomic isotopes whose optical absorption spectra overlap because of the hyperfine splitting. Our estimates demonstrate that the selectivity of spatial separation of optically aligned ¹³⁷Cs and ¹³³Cs isotopes can be at least 10¹².