Triggered parallel discharge in laser-ablation spark-induced breakdown spectroscopy and studies on its analytical performance for aluminum and brass samples

Highlights: • A gated pulsed HV power supply was used as excitation source of the spark discharge. • Parallel discharge was realized by increasing time delay between HV and laser pulses. • No samples could be ablated by the spark discharge under parallel discharge mode. • Obvious signal enhancement has been observed under parallel discharge mode. • 4–10 folds enhancement factors in LOD of the analytes have been achieved currently. In laser-ablation spark-induced breakdown spectroscopy (LA-SIBS), the discharge channel is an important factor to affect both analytical sensitivity and lateral resolution on the sample surface. In order to study this effect, a gated pulsed high-voltage power supply was selected as the power source of the spark discharge, the dependence of the discharge channel on the time delay between the high voltage pulse and the laser pulse was studied in this work. It was demonstrated that under suitable laser pulse energy and geometrical arrangement of the electrodes, it was possible to change V-shape discharge to parallel discharge by increasing this time delay. In the V-shape discharge, the spark discharge could ablate more samples and increase the diameters and depths of the craters; however, in the parallel discharge, the spark discharge hardly ablated new samples, to make sure that the spatial resolution in LA-SIBS was only determined by the laser ablation. Under parallel discharge, the intensity of the atomic emission of the plasma decreases with the increasing of time delay but increases with the increasing of the discharge voltage. 4–10 folds enhancement factors have been achieved in the detection limits of the analytes in the employed targets under current experimental conditions. It is suggested that spark discharge under external trigger mode should be selected to realize parallel discharge if high spatial resolution elemental analysis of solid samples is required.