Direct comparison of ns LIBS and fs LIBS with high spatial and temporal resolution in gases

Abstract Spatial resolution is one of the most critical parameters for spectroscopic measurements especially when used in gases. However, the lateral resolution of femtosecond (fs) laser-induced breakdown spectroscopy (LIBS) in gases has not been thoroughly investigated. Here, we directly compare the differences and connections between nanosecond (ns) LIBS and fs LIBS through spatio-temporally resolved spectroscopy. At the time period we measured, unlike the ns LIBS plasma, the fs LIBS plasma does not show detectable expansion, and we do not find composition transport due to turbulence inside the fs LIBS. In other words, the local spectral emission in the fs LIBS can correlate precisely to the composition at that location before the arrival of the laser, while ns LIBS cannot. This feature allows fs LIBS to have much higher lateral resolution than ns LIBS. Finally, this paper verified that fs LIBS can be used for one-dimensional measurements capability with its lateral resolution of 50 μ m.