INDUCED BREAKDOWN SPECTROSCOPY; BORON ISOTOPIC RATIO; ABLATION PLASMAS; EMISSION FEATURES; INFRARED-SPECTRA; ENERGY-LEVELS; LIBS; NANOSECOND; SPECTROMETRY; PERFORMANCE
We report on the observation of uranium monoxide (UO) emission following fs laser ablation (LA) of a uranium metal sample. The formation and evolution of the molecular emission is studied under various ambient air pressures. Observation of UO emission spectra at a rarefied residual air pressure of similar to 1 Torr indicates that the UO molecule is readily formed in the expanding plasma with trace concentrations of oxygen present within the vacuum chamber. The persistence of the UO emission exceeded that of the atomic emission; however, the molecular emission was delayed in time compared to the atomic emission due to the necessary cooling and expansion of the plasma before the UO molecules can form. (C) 2017 Optical Society of America