Self-absorption effects of laser-induced breakdown spectroscopy under different gases and gas pressures

The self-absorption effect is one of the main factors affecting the quantitative analysis accuracy of laser-induced breakdown spectroscopy. In this paper, the self-absorption effects of laser-induced 7050 Al alloy plasma under different pressures in air, Ar, and N₂ have been studied. Compared with air and N₂, Ar significantly enhances the spectral signal. Furthermore, the spectral self-absorption coefficient is calculated to quantify the degree of self-absorption, and the influences of gas species and gas pressure on self-absorption are analyzed. In addition, it is found that the spectral intensity fluctuates with the change of pressure of three gases. It can also be seen that the fluctuation of spectral intensity with pressure is eliminated after correcting, which indicates that the self-absorption leads to the fluctuation of spectral intensity under different pressures. The analysis shows that the evolution of optical thin spectral lines with pressure in different gases is mainly determined by the gas properties and the competition between plasma confinement and Rayleigh–Taylor instability.