The Influence Of Laser-Induced Breakdown Plasma Self-Absorption Effect For Soil Element Detection Precision

Laser-induced breakdown spectroscopy(LIBS)has the advantages of rapid,in situ,real-time,noninvasive multi-element analytical method,which is widely employed in agriculture,mining,manufacturing,power and thermal manufacturing,catering and other fields.Facing increasingly serious soil heavy metal pollution,research to develop sensitive and fast,efficient and accurate component spectrum detection method of soil elements,to adapt the large area of land survey,heavy monitoring mission,to promote digital environmental assessment of agricultural production,improve the level of agricultural production safety is the current important research topics.In this paper,we are aiming at the absorption phenomenon of laser-induced plasma,and the influence of laser-induced breakdown plasma self-absorption effect for soil element detection precision.The main work and results are as follows:(1)The method of improving the high-precision quantitative analysis of heavy metal soil samples.On the platform of the test device,on the basis of experimental parameters optimization,the existing in the research of laser induced breakdown spectroscopy absorption phenomenon,calculate the absorption coefficient,and through the relevant correction method to modify characteristic spectral lines,the absorption correction model is set up,to improve the laser induced breakdown spectroscopy for the accuracy of measurement of soil heavy metal elements.Combined with WT and SA methods,the fitting values of Cr(I)357.86 nm?Cr(I)425.44 nm?Cr(I)427.49 nm and Pb(I)405.78 nm are 0.993?0.992?0.996 and 0.995,the RMSECV are 0.19,0.16,0.28 and 0.29,respectively.The detection limits are 30.64,19.95,31.17 and 29.33 mg/kg,respectively.The results shown that the high-precision quantitative analysis of heavy metal soil samples is improved by using WT and SA hybrid model.(2)The method of high-precision classification method of heavy metal soil samples.Based on the experimental parameter optimization and self-absorption spectrum correction,the soil samples with different concentrations of heavy metals are analyzed by principal component analysis,and the results of quantitative analysis of heavy metals in soil are calibrated and classified by reducing matrix differences.Combined with WT and SA methods,the contribution rate of the first three principal components is 61.32%,25.78%and 11.86%,respectively,and the cumulative contribution rate is 98.96%.LIBS technologycombined with the spectral self-absorption correction model and PCA classification model reduced the interference of other elements in the matrix,and the contribution rate of Fe(I)396.65 nm and Fe(I)593.47 nm characteristic spectral lines decreased from 6.48% to0.65%.In this paper,the influence of laser-induced breakdown plasma self-Absorption effect for soil element detection precision is investigated.Based on the spectral self-absorption corrected model,the results of high-precision quantitative analysis and classification of heavy metal soil sample is achieved.These research results are helpful for the detection ability of LIBS technology,include the large area of land survey,heavy monitoring work,and the digital agricultural production environment assessment.