Dual-wavelength laser induced breakdown spectroscopic technique for emission enhancement in vacuum

A novel approach of dual-wavelength LIBS with a single Nd 3+ :YAG laser is proposed and demonstrated for lunar-simulant analysis in high vacuum conditions. Laser ablation was performed at 355 nm/532 nm wavelength, and subsequently, the plasma was reexcited with the fundamental (1064 nm) wavelength. The interpulse delay was adjusted by varying the optical path length. A significant line intensity enhancement up to a factor of 3 was observed for many of the dominant emission lines of the lunar simulant sample. A theoretical model for understanding the mechanism behind the intensity improvements of dual-wavelength configurations is also discussed. Experimentally observed plasma temperature was comparable with theoretically estimated plasma temperature of silicon, which is the major constituent of lunar simulant.