Improving the analytical sensitivity of orthogonal double-pulse laser-induced breakdown spectroscopy with target-enhancement

The analytical sensitivity of conventional reheating orthogonal double-pulse laser-induced breakdown spectroscopy (ODP-LIBS) was improved using a solid target. In the experiments, the first laser was shot on the sample surface to produce sample plasma and the second time-delayed laser was shot on the target surface to produce target plasma. Sample and target were spatially arranged with orthogonal orientations. Through the interaction between target plasma and sample plasma, the optical emissions of the analytes can be enhanced significantly. To evaluate the analytical sensitivity improvement factor of this technique, copper and lead in water samples were quantitatively analyzed using wood slice as water absorber to realize matrix conversion. The detection limit of copper and lead in water determined with this technique using aluminum target was 49 ng/mL and 180 ng/mL, respectively. The enhancement factor in comparison with those obtained by ODP-LIBS without using targetenhancement was 4.5 and 3.8, respectively. This work demonstrates that the analytical sensitivity of ODPLIBS can be obviously improved with target-enhancement.