Hybrid interferometric/dispersive atomic spectroscopy of laser-induced uranium plasma

An established optical emission spectroscopy technique, laser-induced breakdown spectroscopy (LIES), holds promise for detection and rapid analysis of elements relevant for nuclear safeguards, nonproliferation, and nuclear power, including the measurement of isotope ratios. One such important application of LIBS is the measurement of uranium enrichment (U-235/U-238), which requires high spectral resolution (e.g., 25 pm for the 424.4 nm U II line). High-resolution dispersive spectrometers necessary for such measurements are typically bulky and expensive. We demonstrate the use of an alternative measurement approach, which is based on an inexpensive and compact Fabry-Perot etalon integrated with a low to moderate resolution Czerny-Turner spectrometer, to achieve the resolution needed for isotope selectivity of LIES of uranium in ambient air. Spectral line widths of similar to 10 pm have been measured at a center wavelength 424.437 nm, clearly discriminating the natural from the highly enriched uranium. (C) 2015 Elsevier B.V. All rights reserved.