Sensitive elemental analysis with high repetition rate laser-ablation spark-induced breakdown spectroscopy combined with lock-in signal detection

Abstract

High repetition rate laser-ablation spark-induced breakdown spectroscopy (HRR LA-SIBS) combined with lock-in signal detection was developed to realize sensitive trace elements analysis. In order to realize the lock-in signal detection, the repetition rate of laser pulses was increased to 4 kHz and the time duration of the plasma emission was prolonged to be about 10 microseconds by the spark discharge, thus the duty cycle has been increased to 4% approximately. The influence of the continuum background of the plasma emission to the signal detection was reduced with a gated preamplifier. Trace lead and aluminum in brass samples and trace chromium and manganese in aluminum alloy samples were analyzed experimentally. The detection limits of them were estimated to be about 112, 178, 235 and 202 ppb under current experimental condition, demonstrating an obvious improvement on the analytical sensitivity of this technique comparing with conventional single pulse laser-induced breakdown spectroscopy. The HRR LA-SIBS technique combined with lock-in signal detection can be potentially applied to realize direct and sensitive elemental analysis of different solid samples.