Double-enhanced LIBS system with N2 atmosphere and cylindrical cavity confinement for quantitative analysis of Sr element in soil

Abstract

To effectively improve the quality of laser-induced plasma spectra and the detection accuracy of laser-induced breakdown spectroscopy (LIBS) simultaneously for Sr element in soil, the dual mechanism of N2 atmosphere combined with cylindrical cavity confinement for laser-induced Sr plasma emission enhancement was proposed and investigated in this paper, and a multi-spectral fusion internal standard analysis model was established. Optimum enhancement effect can be achieved under the conditions of 2 mm diameter and 6 mm height of the confinement cavity in N2 atmosphere, where the enhancement factor was about 3.25, the signal-to-noise ratio reached 710.28, and the LIBS spectrum quality was the best; the relative standard deviation value (2.64%) was the smallest, and the LIBS signal reproducibility was the best. For the samples in this study, the limit of detection of the sample Sr elements under the dual enhancement mechanism was 34.60 mg kg−1, which was 40.43% lower than the limit of detection (LOD) without enhancement mechanism (58.08 mg kg−1), and the R 2 of the multispectral fusion internal standard model was 1.23% higher and the relative error was 3.41% lower than that of the internal standard method. The results showed that the dual enhancement mechanism combining N2 atmosphere and cylindrical cavity confinement improved the spectral quality, signal reproducibility, and detection sensitivity.