Isotopic analysis of uranium using glow discharge optogalvanic spectroscopy and diode lasers

A hollow cathode glow discharge has been coupled with tunable lasers for isotopically selective excitation of gaseous uranium atoms produced by cathodic sputtering. A CW argon ion laser-pumped titanium:sapphire ring laser and a semiconductor diode laser were employed. Optogalvanic detection of the discharge atom population allowed identification of 235U at depleted, natural, and enriched abundances in uranium metal and uranium oxide samples based on the spectral signatures of two transitions. Isotope ratio measurements were precise from run to run (internal precision) to better than +1% relative standard deviation at 1σ; external precision (sample to sample) was on the order of ±3% relative standard deviation at 1σ. As in mass spectrometry, the most accurate analysis will be obtained when a bias correction is employed to correct for day to day variations in the laser and discharge conditions. 24 refs., 4 figs., 1 tab