Standoff analysis of laser-produced plasmas using laser-induced fluorescence

We report the use of laser-induced fluorescence (LIF) of laser ablation (LA) plumes for standoff applications. The standoff analysis of Al, as major and minor species in samples, is performed in a nanosecond laser-produced plasma created at a distance of similar to 10 m. The LIF of LA plumes is carried out by resonantly exciting an Al transition at 394.4 nm (S-2(1/2) - P-2(1/2)) using a continuous wave (cw) tunable laser and by collecting the direct-line fluorescence signal at 396.15 nm. The spectral resolution of LIF is obtained by scanning the cw tunable LIF laser across the selected Al transition. Our results highlight that LIF provides enhanced signal intensity, emission persistence, and spectral resolution when compared to thermally excited emission. (C) 2018 Optical Society of America