Correction of self-absorption effect in calibration-free laser-induced breakdown spectroscopy by an internal reference method.
A simplified procedure for correcting self-absorption effect was proposed in calibration-free laser-induced breakdown spectroscopy (CF-LIBS). In typical LIBS measurement conditions, the plasma produced is often optically thick, especially for the strong lines of major elements. The selection of self-absorption lines destroys the performance of CF-LIBS, and the familiar correction method based on the curve of growth is complex in implementation. The procedure we proposed, named internal reference for self-absorption correction (IRSAC), first chose an internal reference line for each species, then compared other spectral line intensity of the same species with the reference line to estimate the self-absorption degrees of other spectral lines, and finally achieved an optimal correction by a regressive algorithm. The self-absorption effect of the selected reference line can be ignored, since the reference line with high excitation energy of the upper level is slightly affected by the self-absorption. Through the IRSAC method, the points on the Boltzmann plot become more regular, and the evaluations of the plasma temperature and material composition are more accurate than the basic CF-LIBS.
Sun
Lanxiang
L
Key Laboratory of Industrial Informatics, Shenyang Institute of Automation, Chinese Academy of Sciences, Shenyang 110016, China. sunlanxiang@sia.cn
Yu
Haibin
H
D000042:Absorption; D000465:Algorithms; D007834:Lasers; D008722:Methods; D012015:Reference Standards; D013057:Spectrum Analysis / Q000379:methods* / Q000592:standards; D013696:Temperature