Isotope selective excitation and separation method and apparatus utilizing circularly polarized pulsed radiation

The isotopes of a gas are separated by using a circularly polarized laser to excite a lower energy level to higher split intermediate energy levels, a second laser pulse of the same circular polarization is applied to said energized gas at a time π/Δω where πΔ is the frequency splitting of the intermediate levels, to excite the excited intermediate levels to a higher energy level where an ionizing field ionizes the atoms or molecules in the higher level so that they may be separated from the unionized atoms or molecules of the other isotope