样品加热结合空间约束的飞秒激光诱导击穿光谱用于合金元素定量分析研究

铝合金是工业应用中最广泛的有色金属,添加一定元素形成的合金成为理想的结构材料,如何快速、精确的检测合金中元素的含量是生产和使用中的关键问题。实验基于样品加热结合空间约束的飞秒激光诱导击穿光谱方法(Femtosecond laser-induced breakdown spectroscopy,fs-LIBS)对铝合金元素进行了定量分析,探讨了样品加热结合空间约束条件下等离子体辐射光谱增强、稳定性提高的物理原因。实验结果发现,利用样品加热空间约束方法,等离子体辐射光谱增强,随着靶材温度的升高,等离子体辐射存在时间也明显延长;通过对铝合金系列中的Mn元素进行分析,比较了无约束、空间约束和样品加热结合空间约束实验条件下fs-LIBS的检出限、相对标准偏差和拟合度值,相比于无约束fs-LIBS,通过样品加热空间约束,在样品温度为150℃时,检出限和相对标准偏差值分别大约降低到原来的1/5和1/4,同时拟合度达到0.99以上。因此,利用样品加热结合空间约束方法,可以提高LIBS技术对于合金元素定量分析的探测灵敏度和分析精度。

The quantitative analysis of alloy element by femtosecond laser-induced breakdown spectroscopy with sample heating and spatial confinement

Aluminum alloy was the most commonly used nonferrous metal material in industry, which was formed by adding certain elements, and become an ideal structural materials. How to detect the content of elements in alloy quickly and accurately was also a key problem in production and application. The quantitative analysis of aluminium alloy element by femtosecond laser-induced breakdown spectroscopy methods with sample heating and spatial confinement was investigated. The physical reason of plasma emission spectral intensity enhanced and stability improved was discussed. The experimental results showed that femtosecond laser produced plasma emission spectral intensity effectively enhanced under the sample heating and spatial confinement and the plasma emission delay had a significantly extension with the sample temperature increased. Besides, the Mn element of aluminium alloy series was determined, and the limits of detection, relative standard deviation, R-squared of fs-LIBS under three conditions, including no confinement, spatial confinement and sample heating combined with spatial confinement, were compared. It was found that the limits of detection and relative standard deviation of sample heating at 150℃ combined with spatial confinement was reduced to 1/5 and 1/4 of those obtained by no confinement, respectively, and the R-squared was above 0.99. Hence, the detection sensitivity and analytical precision of alloy element quantitative analysis in LIBS could be improved by combining sample heating and spatial confinement.