Low-level measurements of carbon concentrations in steel using laser-induced plasma spectroscopy (LIPS)

Abstract

Time-integrated, spatially resolved emission spectroscopy, in the deep vacuum ultraviolet (VUV) region (40-160 nm), of laser-produced plasmas has been employed for the quantitative characterization of the carbon content in solid steel target materials; the samples under study contained carbon concentrations in the 0.001-1.32% range. Six prominent VUV carbon spectral lines, representing three different ionization stages, were selected and proved to be spectral-interference free. Several experimental parameters and conditions such as the focusing lens type, laser power density, background atmospheres and pressure were optimized, leading to an unprecedented lower limit of detection, for carbon in solid steel alloys, of 1.2 ppm (parts per million) obtained with the 97.70 nm CIII spectral line. Furthermore, the spectroscopic evaluation of the steel plasma physical parameters is briefly presented.