| Popis: |
Laser induced breakdown spectroscopy (LIBS) is an analysis technique based on laser plasma atomic emission spectroscopy. Because of its speed, non-destructive and high sensitivity, it is widely used in various fields. In order to study the laser-induced breakdown spectra of heavy metals and non-metal elements in the soil, and solve the problem of low accuracy of LIBS quantitative analysis due to spectral baseline drift, an Adaptive Iterative Re-weighted Partial Least Squares (air-PLS) baseline correction method is proposed to improve the accuracy of LIBS quantitative analysis. In this paper, 8 kinds of standard soil samples are used, 2 grams of each were extracted and placed in a tableting mold, using a 20MPa hydraulic press to form a smooth sheet with a diameter of 30mm and a thickness of 3mm for use. The laser energy was set to 30mJ, and the pulse repetition frequency was set to 5Hz. Plasma spectral lines of metal element Mg of different samples were obtained through experiments, and linear PLS was used to model and analyze the original spectrum and the spectrum after baseline correction respectively. Experimental results show that the accuracy of LIBS quantitative analysis is greatly improved after baseline correction. After using the method described in this article for baseline correction, the coefficient of determination R2 increased from 0.9553 to 0.9858, and the root mean square error RMSEC decreased from 1.5610 to 0.8571. The accuracy of LIBS quantitative analysis has been significantly improved. The study of this technology can provide guidance for the quantitative analysis of Mg and other elements in the soil. |
