Double Pulse RLIBS: A New Approach for Sensitive and Quasi-Non-Destructive Sample Analysis

This study investigates a new regime of double-pulse resonance laser-induced breakdown spectroscopy (DP-RLIBS), that allows highly sensitive trace element detection with virtually no sample damage. In DP-RLIBS, a single laser pulse at a wavelength chosen to selectively excite a trace element of interest is split into two pulses: a direct pulse used for surface ablation and a delayed pulse used to excite the vapor generated by the direct pulse. We show that the new DP-RLIBS regime investigated here achieves a limit of detection (LoD) of 0.6 ppm for lead (excitation/fluorescence at 283.31/405.78 nm) and 0.8 ppm for iron (excitation/fluorescence at 296.69/373.49 nm) in copper samples using 100 laser shots, far exceeding the capabilities of conventional LIBS, which showed an LoD of 85 ppm for lead when both methods used the same energy of 600 μJ and the same number of laser shots. The DP-RLIBS technique provided accurate calibration curves with high linearity in the range of 0-1100 ppm for lead and a quadratic behavior for iron in the range 0-2100 ppm. Scanning electron microscopy (SEM) images confirmed the nondestructive nature of DP-RLIBS, showing no damage to the sample even after 10,000 laser shots, in contrast to the significant damage observed with conventional LIBS after only 100 shots. These results underscore the potential of DP-RLIBS for delicate analyses requiring high sensitivity and minimal impact on the sample.