ns- and fs-LIBS of copper-based-alloys: A different approach

A self-calibrated analytical technique, based on plasmas induced by either 250 fs or 7 ns laser pulses, is presented. This approach is comparable to other calibration-free methods based on LTE assumption. In order to apply this method to very different laser pulse durations, the partial-local thermodynamic equilibrium (p-LTE) has been considered within the energy range of 30,000-50,000 cm−1. In order to obtain the neutral species densities, the detected plasma species emission lines intensities have been treated together with the experimental evaluated background black-body Planck-like emission distribution. For validating the followed method, three certified copper-based-alloys standards were employed and their minor components (Ni, Pb and Sn) amounts were determined. As a result, it arises, that this standardless method, independently from the laser source pulse durations, provides good quantitative analysis, and, consequently, that the composition of the plasma plume emitting species induced is not affected by the laser pulse time width.