铁合金中微量钛元素的激光诱导击穿光谱研究

采用激光诱导击穿光谱对铁(Fe)合金中的钛元素(Ti)的含量进行测量。实验中激光器在最大能量输出(50 mJ)，延时为1 μs时光谱信号的强度值最大。在此条件下，分别使用传统定标法和Fe Ⅰ 438.35 nm及Fe Ⅰ 427.12 nm两条谱线的内标法对铁合金中的Ti进行定量分析。内标法得到的拟合相关系数(r)分别为0.997 8和0.993 9，优于传统法得到的r(0.956 3)。提出了一种双谱线平均内标法，拟合得出r为0.998 4。同时，在浓度为0.063%～1.9%的范围内传统定标法测量的相对误差为23.7%，内标法的相对误差为6.0%，采用平均内标法后相对误差降为3.9%。最后，通过测量的Ti光谱计算了激光能量为50 mJ时所产生的等离子体温度为6 654.3 K，电子密度为1.072×1022 cm-3，并讨论了激光能量与烧蚀产生等离子体温度之间的关系。

Trace Titanium in Ferroalloy Studied by the Laser Induced Breakdown Spectroscopy

The concentration of titanium element in the ferroalloys was measured by laser induced breakdown spectroscopy. The maximum spectral signals were observed at the output energy of pulse laser at 50 mJ and the delay at 1 μs. Under this circumstance, traditional calibration method (TCM) and internal standard method (ISM) with Fe Ⅰ 438.35 nm and Fe Ⅰ 427.12 nm lines were used to quantitatively analyze the Ti in iron alloy. The fitting correlation coefficients (r) of ISM were 0.997 8 and 0.993 9 for Fe Ⅰ 438.35 nm and Fe Ⅰ 427.12 nm respectively, higher than that of TCM (0.956 3). This paper presented a double-line average internal standard method and resulted in 0.998 4 for r. In the range of Ti concentration from 0.063% to 1.9%, the relative errors were 23.7% and 6.0% for the TCM and ISM respectively. However, the relative error was reduced to 3.9% by the double-line average internal standard method. In addition, the temperature of plasma Ti was 6 654.3 K and the electron density was 1.072×1022 cm-3 through calculating the obtaining lines of Ti at the laser energy of 50 mJ. Furthermore, the relationship between the laser energy and the plasma temperature was discussed in the paper.