Self-reversal effect elimination in laser-induced breakdown spectroscopy by employing single-probe microwave radiation

Abstract

The self-absorption effect in laser-induced breakdown spectroscopy (LIBS) has always been a bottleneck that causes spectral distortion even self-reversal, and poor quantitative accuracy, limiting the engineering application of LIBS. Microwave-assisted LIBS (MA-LIBS) has proven to be feasible to weaken the self-absorption effect, but the stability of microwave excitation and the microwave radiator need to be improved. In this study, a new single-probe microwave radiator was proposed to achieve superior injection of microwave power for the elimination of the self-reversal effect. The electromagnetic simulations of the single-probe radiator were first conducted for efficient microwave coupling. To evaluate the performance of the single-probe radiator, the effect of microwave parameters on self-reversal elimination of typical self-absorption elements sodium (Na) and potassium (K) in potassium feldspar samples was investigated and optimized. With the increase in microwave power, self-reversal was eliminated. Also, spectral evolution measurements have been performed and the results indicated significant self-reversal elimination and prolonged plasma lifetime in MA-LIBS. The results indicated that MA-LIBS with single-probe microwave excitation showed excellent potential in eliminating the self-reversal phenomenon and provided technical support for the application of LIBS.