RESUMO
In this work, laser-induced breakdown spectroscopy (LIBS) is applied for quantitative measurements of Pb in aerosols. In order to investigate the carrier gas role and, in particular, the effect of O2 addition to the gas itself, measurements are carried out in nitrogen and air atmosphere. Aerosol particles are produced by nebulizing Pb(CH3COO)2 * 3H2O aqueous solutions of known concentration and the atomic line of 405.8 nm is detected as Pb signature. The plasma generated with the laser pulse is characterized in terms of plasma temperature and electron density, showing no substantial differences with the two carrier gases used. The behavior of the LIBS signal as a function of the delay time with respect to the laser pulse is investigated changing the environmental conditions and, in particular, the Pb concentration values. The different trends registered in the case of relatively short (up to 20 µs) and long delay time, resulting to be the same whatever the Pb concentration value, could have a significant effect on the calibration curve performed in different experimental conditions.
