基于电子温度与电子密度的光谱自吸收校正  

Spectral Self⁃Absorption Correction Based on Electron Temperature and Electron Density

作　　者：杨彦伟 张丽丽 张瑞忠 Yang Yanwei;Zhang Lili;Zhang Ruizhong(Department of Physics,Lüliang University,Lüliang 033000,Shanxi,China;Key Laboratory of Instrumentation Science and Dynamic Measurement,Ministry of Education,NorthUniversity of China,Taiyuan 030051,Shanxi,China;Shanxi Huaxing Aluminum Industry Co.,Ltd.,Lüliang 033603,Shanxi,China)

机构地区：[1]吕梁学院物理系,山西吕梁033000 [2]中北大学仪器科学与动态测试教育部重点实验室,山西太原030051 [3]山西华兴铝业有限公司,山西吕梁033603

出　　处：《中国激光》2024年第17期313-319,共7页Chinese Journal of Lasers

基　　金：山西省自然科学基金(201901D1111620);2022年吕梁市科技局人才引进项目(2022RC13);2023年山西省教改项目(J20231374);山西省“1331工程”重点学科建设计划。

摘　　要：针对激光诱导击穿光谱自吸收影响铝土矿定量检测精度的问题,提出基于等离子体电子温度与电子密度的自吸收校正方法,建立了双重自吸收校正模型,实现了铝土矿主要元素的发射光谱自吸收校正。通过激光诱导击穿光谱(LIBS)技术激发铝土矿元素光谱,结合NIST库筛选出铝土矿样品中Al、Si、Fe、Ti元素的主要特征谱线,并利用元素能级性质选定内参考线,通过比较玻尔兹曼图决定系数(R2)与自由定标激光诱导击穿光谱(CF-LIBS)定量分析精度,验证了提出的自吸收校正模型的可行性。通过计算等离子体电子温度确定谱线自吸收系数,完成谱线的第一次校正,结果显示Al、Si、Fe、Ti元素含量的准确性分别提高了5.21%、5.94%、11.28%和5.62%;利用谱线展宽理论及电子密度,完成了谱线的第二次校正,结果显示主要元素含量的准确性进一步提高了3.19%、4.26%、4.49%和3.37%。经过两次校正,样本中各元素的玻尔兹曼拟合系数得到了很大改善,定量分析精度得到了提高。Objective To address the problem of the self-absorption of laser-induced breakdown spectroscopy affecting the quantitative detection accuracy of bauxite,a self-absorption correction method based on the plasma electron temperature and electron density is proposed,and a double self-absorption correction model is established to realize the self-absorption correction of the emission spectra of the main elements in bauxite.Methods A laser-induced breakdown spectroscopy(LIBS)diagram is shown in Fig.1.LIBS is used to excite the spectrum of The ablation acquisition spectra are obtained at nine different positions arranged in a matrix form on the bauxite sample.After five cleaning cycles,ablation is performed at each position.After excluding the abnormal data,the average value of the remaining data is used as the final spectral data value of the sample.The first correction is completed using the internal reference lines and electron temperature,and the second correction is completed using the spectral line broadening theory and electron density.Results and Discussions The plasma emission spectrum of the bauxite sample covers the region from 190 nm to 980 nm(Fig.2).A Boltzmann curve is drawn using the spectral intensity and parameters of each element to obtain the plasma electron temperature.The self-absorption coefficient of the spectral line is then calculated.Boltzmann diagrams of Al,Si,Fe,and Ti before correction are shown in Fig 3.Al I 396.16 nm,Fe I 396.119 nm,Si I 288.158 nm,and Ti I 498.173 nm are used as the internal reference lines to correct the spectral lines.The Boltzmann diagram after the first correction is shown in Fig.4.Taking the corrected spectral peak as the highest point,the actual spectral line broadening in the case of self-absorption can be obtained via Lorentz fitting.At the same time,the electron density is calculated by using the Hαline,and the Hαline spectrum of bauxite is shown in Fig.5.The self-absorption coefficient is calculated using the electron density and actual spectral line broadenin

关 键 词：激光诱导击穿光谱 自吸收校正 电子温度 电子密度 

分 类 号：O433.4[机械工程—光学工程]