不同气氛下飞灰含碳量的激光诱导击穿光谱分析

Quantitative Analysis of Unburned Carbon in Fly Ash by LaserInduced Breakdown Spectroscopy in Different Atmosphere

利用激光诱导击穿光谱(LIBS)技术进行飞灰含碳量分析时常用的C I 247.86 nm谱线附近存在强烈的谱线干扰。位于深紫外区无干扰的C I 193.09 nm常用作分析谱线以避免谱线干扰,但该谱线在空气中会被氧气吸收而影响定量分析的准确性。为了进一步提高利用该谱线定量分析飞灰含碳量效果,在光谱仪中充入氩气并在等离子体区域用氩气吹扫,对比分析了两种气氛下采用C I 193.09 nm谱线定量分析飞灰含碳量的效果。研究结果表明,在氩气气氛下获得的谱线强度及其信噪比、重复测量精度和含碳量的检测限均有显著改善,两个检验样品的含碳量预测绝对误差分别降至0.02%和0.42%(质量分数),含碳量的检测限也降至0.37%(质量分数)。

The spectral line C I 247.86 nm which is widely used to analyze unburned carbon in fly ash by laser-induced breakdown spectroscopy（LIBS） shows strong spectrum interference. Another spectral line C I 193.09 nm located in deep ultraviolet area is frequently used to avoid the strong interference. However, it is strongly absorbed by oxygen in air, which affects the accuracy of quantitative analysis. In order to improve the performance of quantitative analysis by using C I 193.09 nm line, the spectrometer is filled with argon and the argon environment is formed in the region where the plasma emerges. The quantitative analysis results of unburned carbon in air and argon atmosphere by using C I 193.09 nm line are compared. The results indicate that the line intensity, signal- to- noise ratio, repeated measurement precision and limit of detection are improved significantly. Meanwhile, the absolute error between predicted concentration and actual concentration for two test samples is reduced to 0.02% and 0.42%（mass fraction）,respectively in argon atmospheric environment, and the limit of detection is also reduced to a relatively low level of0.37%（mass fraction）.