Spectral line selection for time-resolved investigations of laser-induced plasmas by an iterative Boltzmann plot method
Spectral line selection for time-resolved investigations of laser-induced plasmas by an iterative Boltzmann plot method
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DOI：
10.1016/j.sab.2008.08.003
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发表时间：
2008-10
期刊：
影响因子：
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通讯作者：
Ü. Aydin;P. Roth;C. Gehlen;R. Noll
中科院分区：
文献类型：
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作者：
Ü. Aydin;P. Roth;C. Gehlen;R. Noll
本工作的目的是提供一个程序，以确定时间分辨的电子温度与最小的相对误差的玻尔兹曼图方法。应用程序包括两个部分，一个系统的理论谱线选择和迭代玻尔兹曼图算法。在预先选择特定原子或离子种类的谱线的适当的非干扰或重叠的集合之后，使用针对每个时间窗口和感兴趣的激光脉冲能量的实验记录的数据来生成玻尔兹曼图。假设具有与回归函数的最高平均偏差的谱线不代表所考虑的谱线集合，因此逐渐丢弃，直到超过确定系数的阈值。利用激光诱导击穿光谱（LIBS）技术对1.1750 C75钢合金样品的等离子体进行了时间分辨和空间积分研究，激光脉冲能量范围为200 μJ ~ 2 mJ。对于这些样品的特定化学组成的原子和离子铁谱线的选择已经进行。尽管事实上，只有在低毫焦耳制度的激光脉冲能量被施加的光谱线的最终组包括在总数61 Fe I和12 Fe II发射线。用这种方法可以确定电子温度的平均相对误差下降到1.8%的Fe I和4.4%的Fe II发射线。
The aim of this work is to provide a procedure to determine time-resolved electron temperatures with minimized relative errors by the Boltzmann plot method. The applied procedure consists of two parts, a systematic theoretical spectral line selection and an iterative Boltzmann plot algorithm. After a pre-selection of an appropriate non-disturbed or overlapped set of spectral lines of a particular atomic or ionic species Boltzmann plots are generated using experimentally recorded data for every time window and laser pulse energy of interest. Spectral lines with the highest average deviations from the regression function are assumed as being not representative for the considered ensemble of spectral lines and are therefore discarded gradually until a threshold value for the coefficient of determination is exceeded. Laser-induced breakdown spectroscopy (LIBS) is applied for time-resolved and spatially integrated investigations of plasmas on 1.1750 C75 steel alloy samples with laser pulse energies ranging between 200 µJ and 2 mJ. For the specific chemical composition of these samples a selection of atomic and ionic Fe spectral lines has been carried out. In spite of the fact that only laser pulse energies in the low millijoule regime are applied the final sets of spectral lines comprise in total 61 Fe I and 12 Fe II emission lines. By applying this method electron temperatures can be determined with averaged relative errors of down to 1.8% for Fe I and 4.4% for Fe II emission lines.