Laser isotope separation of lithium by two-step photoionization

Lithium isotope separation has been achieved employing the two-step photoionization technique along with a narrow band dye laser in conjunction with a time of flight mass spectrometer. The demonstrated method yields a high degree of selectivity by tuning the dye laser at the resonance levels of Li-6 and Li-7. It is inferred that the concentration of the natural abundance of the Li-6 isotope gets enhanced up to over 47% as the exciter dye laser is tuned to the P-2(1/2) of Li-6 even if the linewidth of the exciter laser is not sufficiently narrow to excite the isotopic level. It is also noticed that the much higher energy density of the exciter laser limits the resolution of the fine structure levels of the lithium isotopes that leads to a loss in the enrichment of Li-6 due to the power-broadening effect. Measurements of the photoionization cross section of the lithium isotopes from the 2p P-2(1/2,3/2), excited states for Li-6 and Li-7 and the corresponding number densities are reported. (c) 2006 American Institute of Physics.