Spatial and Temporal Dependence of Lead Emission in Laser-Induced Breakdown Spectroscopy

Two-dimensional images of the distribution in space and time of the chemical species associated with the spectral emission from a laser-induced breakdown (LIB) plasma on a solid sample were captured. The time-dependent spatial shape and size of the plasma, viewed simultaneously from two orthogonal directions, were measured in terms of the emission from a lead ionic line and a set of lead atomic lines. The temporal and spatial behavior are characteristically different for the different spectral lines. The ionic emission (220 nm) is confined to a smaller, more concentrated central part of the LIB plasma, whereas the atomic emission (280 nm) is more evenly dispersed over the entire plasma. A protrusion of the plasma was observed where there was no significant emission at 220 or 280 nm. Time-resolved spectral imaging has the potential to considerably improve analytical LIB spectroscopy (LIBS) results and lead to a better fundamental understanding of its behavior.