Laser isotope separation scheme of lithium by three-color photoionization

Abstract

Lithium isotopes (6,7Li) are of prime importance for nuclear industry. Especially, highly enriched 6Li is needed in fusion reactors to produce clean energy on large scale. In this paper, we report studies on Li isotope separation by isotope-selective three-color photoionization using ‘kHz’ repetition rate narrowband dye lasers in conjunction with time-of-flight mass spectrometer. The method established yields a high degree of selectivity by tuning the dye lasers to respective 6,7Li resonance levels and demonstrated the enhancement of low abundant (7.5%) 6Li up to 92.86% at signal level. The dependence of photo-ionization yield, isotope selectivity and abundance enhancement on laser powers are also investigated. The proposed photo-ionization scheme [2S1/2 → 2P1/2,3/2 → 2D3/2,5/2 1S0 (Li+)] enables the high photo-ionization yield and large enhancement (>12 fold) in 6Li abundance.