玻尔兹曼曲线法在土壤激光诱导击穿光谱谱线识别中的应用研究

Research on Boltzmann Plot Used in Soil Laser Induced Breakdown Spectroscopy for Spectral Line Identification

在激光诱导等离子体满足局部热平衡的情况下,玻尔兹曼曲线法是计算等离子体温度的一种重要手段,对该方法的应用进行了引申和扩展。实验验证激光诱导等离子体处于局部热平衡状态,利用Fe的多条原子谱线建立玻尔兹曼曲线,根据建立的曲线对Fe的其他原子谱线强度进行了反演,反演结果与实验测量结果误差在15%以内。土壤中Fe、Ti、Ca等元素的特征谱线较多,易与其他元素的特征谱线产生重叠,通过这种方法能实现部分谱线的识别与判定,通过建立Mn的玻尔兹曼曲线,求出了Mn 405.89 nm谱线的强度,并分析其对Pb 405.78 nm谱线的影响。研究结果表明,玻尔兹曼曲线法可以对谱线识别起到辅助作用,并且可以加深对定标曲线截距的认识。

As one of the most important ways to calculate the plasma temperature when the laser induced plasma is under local thermal equilibrium condition, the use of Boltzmann algorithm is extended. The experiments prove that the soil laser induced plasma is under local thermal equilibrium condition, then the Boltzmann plot is built by several Fe atomic spectral lines. According to the fitting line, the intensity of other Fe spectral lines are calculated and the error between the calculated and the experimental results is lower than 15%. The characteristic spectral lines of Fe, Ti, Ca in soil are abundant and easy to overlap with other spectral lines. The method can assist identifying and separating some unknown spectral lines. By building the Boltzmann plot of Mn, the intensity of 405.89 nm line is calculated and its impact on the Pb 405.78 nm line is studied. The results show that this method can be applied in the field of spectral line identification and separation.