磁约束下的LIBS技术对土壤中重金属元素检测研究OA

The study investigates the detection of heavy metal elements in several standard soil samples using laser-induced breakdown spectroscopy(LIBS)under magnetic confinement.The copper(Cu)is selected as the primary analysis object.When the external magnetic field strengths of 0 T,0.32 T,and 0.58 T are applied,the spectral intensity and signal-to-background ratio(SBR)of Cu increase.However,a decrease in spectral line intensity is observed when the Cu concentration reaches 147 ppm,which is analyzed to be potentially related to the self-absorption effect.To explore the underlying mechanism of magnetic field enhancement in LIBS,the iron(Fe)with abundant and stable spectral lines is selected for further analysis.The results indicate that the magnetic field significantly increases its electron temperature and density during the plasma evolution stage.To overcome the influence of self-absorption on quantitative analysis,calibration curves for Cu are constructed using the absolute intensity method,considering scenarios with or without magnetic field application and with or without self-absorption correction.Compared to applying only a magnetic field around the sample,the combination of the self-absorption correction method and magnetic confinement improves the detection limit for soil quantitative analysis from 24.94 ppm to 1.167 ppm and increases the correlation coefficient from 0.963 to 0.994.This work demonstrates that the integration of magnetic confinement and self-absorption correction can enhance the spectral performance of LIBS technology and improve the accuracy and sensitivity of heavy metal element detection.