Differential laser absorption spectroscopy of uranium in an atmospheric pressure laser-induced plasma

A two-beam differential laser absorption technique is used to measure 238U absorption spectra with high signal-to-noise ratios in an atmospheric pressure laser-induced plasma. High-resolution absorption spectra are presented for the 238U 861 nm transition in the presence of dry air at pressures up to 760 Torr. A spectral linewidth (FWHM) of 2.23±0.13 GHz was found for the 238U line in dry air at 760 Torr. Absorption spectrum measurements using a low 238U concentration NIST glass standard were used to demonstrate sensitivity of the approach.