Progress in the Correction of Self-Absorption Effect on Laser-Induced Breakdown Spectroscopy

Laser-induced breakdown spectroscopy (LIBS), as a new material composition detection technology, has lots of advantages such as rapid, real-time, micro-damage, in-situ, multi-element analysis and so on. At present, it has been widely used in environmental monitoring, food safety, mineral processing and metallurgy, biomedicine, space exploration and other fields. However, due to the self-absorption, the spectral intensity is reduced. In severe cases, the line profile is even sunken in the centrum ("self-reversal"). The linear coefficient of calibration curve decreases, resulting in the deterioration of the accuracy of element detection, so that large-scale commercial applications cannot be realized. Therefore, the exploration of the self-absorption effect and its correction methods has always been the research hotspot. In this review, the progress of the correction method and the physical mechanism of self-absorption are reviewed. The main correction methods are summarized from the perspectives of experiment parameters optimization, physical assist device, self-absorption model and correction algorithm, respectively. The advantages and disadvantages of the primary correction methods are compared and analyzed. The experiment parameters optimization has the advantages of simple principle and operation. The effect of self-absorption reduction of laser stimulated absorption LIBS (LSA-LIBS) is stable. Microwave assisted excitation LIBS (MAE-LIBS) can reduce the self-absorption effect of multiple elements simultaneously and cost low. The self-absorption coefficient method can directly quantify the degree of self-absorption effect, has simple calculation steps and requires less plasma parameters. The self-absorption correction algorithm based on internal reference line has high calculation efficiency and obvious correction effect. Optically thin method can directly obtain optically thin spectral lines to avoid theoretical errors. Finally, the future research direction and development trend of self-absorption is prospected in our opinion.