Understanding the advantage of remote femtosecond laser-induced breakdown spectroscopy of metallic targets

Abstract

We analyze the advantages of remotely sensing metallic targets using femtosecond laser-induced breakdown spectroscopy by studying the temperature and electron density of the plasma ejected from a lead target produced by femtosecond laser pulse filamentation in ambient air. The electron density of 8×1017cm−3 and the plasma temperature of 6794K were obtained for a 20ns time delay with respect to the laser pulse arriving on the target. With these values the signal is high, while the continuum blackbody radiation is low. The continuum emission in the fluorescence spectra is mainly associated with the supercontinuum of the distorted pulse during filamentation (white light laser) in air and this can be controlled. Extrapolation of the single-shot detection limit shows that this technique of filament-induced breakdown spectroscopy could be extended up to the kilometer range, opening up potential applications in metallurgic industry for remote material analysis and process controls.