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内标法是激光诱导击穿光谱(LIBS)定量分析主要使用的方法之一,采用内标法进行定量分析的关键就是内标参量的选取。以Fe 438.35 nm作为分析谱线,分别选取434~441 nm光谱积分、Al 309.29 nm、Si 288.17 nm、Ca 317.9 nm为内标参量,对水泥样品中的Fe元素进行定量分析,得到的定标曲线线性度分别为0.993、0.962、0.992和0.846。通过分析各内标参量与分析谱线光谱强度比值随积分延迟时间的变化情况,以及针对每个样品选用不同的内标参量得到的多组测量数据的离散程度,得出采用内标法进行LIBS定量分析时,应该选择在积分延迟时间附近光谱强度变化与待测元素的分析谱线最为相似的作为内标参量的结论。这样能有小减弱由于激光器时间抖动导致的定量分析误差,提高定量分析精度。
Internal standard method is one of the main methods used in quantitative analysis of laser induced breakdown spectroscopy (LIBS). The key to quantitative analysis using internal standard method is the selection of internal standard parameters. Taking Fe 438.35 nm as the analytical line, the integrals of 434 ~ 441 nm, Al 309.29 nm, Si 288.17 nm and Ca 317.9 nm were selected as the internal standard parameters respectively. The calibration curves of the Fe element in the cement samples were obtained. The linearity was 0.993, 0.962, 0.992 and 0.846, respectively. By analyzing the variation of spectral intensity ratio of each internal standard parameter and analytical spectrum with the integral delay time and the dispersion degree of multiple sets of measured data obtained by using different internal standard parameters for each sample, it is concluded that the internal standard method for LIBS Quantitative analysis, you should choose the spectral delay in the vicinity of the change in spectral intensity and analysis of the element closest to the analysis of the line as the internal standard parameters of the conclusion. In this way, the quantitative analysis error caused by the laser jitter can be reduced and the quantitative analysis accuracy can be improved.