基于LIBS 技术铝合金中铁元素的定量分析

为了精确得到铝合金标样等离子体的电子温度和电子密度,实验采用激光诱导击穿光谱技术,利用532 nm 调Q Nd:YAG 激光器诱导产生铝合金E311 等离子体。测量铁原子谱线(381.59 nm)的Stark 展宽(0.12 nm)得到等离子体的电子密度是4.31016 cm-3;基于铁原子谱线(370.56, 386.55,387.25, 426.05, 427.18, 430.79, 432.57, 440.48 nm),利用迭代Boltzmann 算法,得到回归系数为0.999时等离子体的电子温度是8 699 K。基于铝合金标样(E311、E312、E313、E314、E315、E316)和铁原子谱线404.58 nm,建立了铁元素的标准曲线,计算得到铁元素的探测限是0.0779 wt%。等离子体特征参数表明铝合金等离子体满足光学薄和局部热力学平衡状态。

Quantitative analysis of the element iron in aluminum alloy using LIBS

In order to precisely analyze electron temperature and electron density of aluminum alloy, the Laser Induced Breakdown Spectroscopy was adopted. The second harmonic of a pulsed Nd:YAG laser (532 nm) has been used for the ablation of aluminum alloy E311 in air at atmospheric pressure and the laser-induced plasma characteristics were examined in detail. The electron density of 4.31016 cm-3 was inferred from the Stark broadening (0.12 nm) of the profile of Fe (I) 381.59 nm. In order to minimize relative errors in calculation of the electron temperature, an improved iterative Boltzmann plot method with eight iron lines (370.56, 386.55, 387.25, 426.05, 427.18, 430.79, 432.57, 440.48 nm) is used. Experimental results show that the electron temperature is 8 699 K with the regression coefficient of 0.999. The calibration curve for iron based on Fe (I) 404.58 nm was established using a set of six samples of standard aluminum alloy (E311, E312, E313, E314, E315, E316) and the detection limit was 0.077 9 wt%. The plasma was verified to be optically thin and in local thermodynamic equilibrium based on the experimental results.