Determination of actinide isotope ratios using glow discharge optogalvanic spectroscopy

Diode laser-excited optogalvanic spectroscopy (OGS) of a glow discharge has been utilized to measure U-235/U-235+U-238 isotope ratios. This 'optical mass spectrometric' measurement has been demonstrated for a number of samples including uranium oxide, fluoride, and metal. Various diode laser-accessible atomic transitions in the 775-835 nm region have been evaluated; these transitions were chosen by considering OGS sensitivity and isotope shift. Using the 831.84 nm uranium line, for example, it was possible to measure the U-235/U-235+U-238 isotope ratio (0.0026) of depleted uranium samples. A prototypical field instrument to make these measurements has been assembled and demonstrated. A U-236 spectral line was identified in an enriched uranium sample, and an abundance was measured. (C) 1998 Elsevier Science S.A.