Advances in signal enhancement mechanism and technology of laser induced breakdown spectroscopy

Laser induced breakdown spectroscopy(LIBS) is a new material identification and quantitative analysis technique, and the low repeatability of the emission spectrum is a key factor in influencing and hindering technology transition from qualitative analysis to quantitative analysis. Therefore, improving the single-to-noise ratio(SNR) and the space stability of plasma are a positive way to improve the spectral repeatability and reduce matrix effect and other unfavorable factors. In addition, SNR enhancement can reduce the requirement of laser output energy, thus effectively reducing the cost of the system based on LIBS, and furthermore facilitating the expansion of LIBS technology to more areas. In this paper, double-pulse and multiple-pulse enhancement, discharge pulse re-excitation, spatial confinement, magnetic field confinement and microwave assisted enhancement are summarized and concluded. Accordingly, the physical mechanism of the spectral enhancement is deeply discussed, which provides strong theoretical basis for further improving of the spectral repeatability and the accuracy of quantitative analysis.