金属特性对激光诱导击穿光谱最佳实验参数的影响

Influence of metal property on the optimized experimental parameters of laser induced breakdown spectroscopy

采用波长为532 nm的单脉冲激光诱导两种金属样品铜和锌,产生等离子光谱,固定激光能量40 mJ、门宽100 ns、光谱仪入射狭缝0.1 mm、ICCD增益100等参数,研究金属样品物理化学特性对会聚透镜焦点到样品表面距离、ICCD采集延迟等最优化实验参数的影响.实验中分别选取铜样品Cu(I)521.82 nm和锌样品Zn(I)481.053 nm谱线作为LIBS信号,实验测定的透镜焦点在距样品表面不同距离处的LIBS信号强度,结果表明铜和锌样品的聚焦透镜焦点分别在样品表面内距表面的距离为5 mm和5.5 mm时得到光谱信号强度最大;铜和锌的ICCD探测延时分别为1300 ns和1100 ns时等离子体光谱信号的信噪比最大并具有可观测的强度,依据铜和锌样品物理化学特性的差异对实验结果进行了合理的分析与讨论,为后续研究金属样品LIBS技术的基底效应、纳米结构增强激光诱导击穿光谱机理提供数据参考.

Single pulse laser with 532 nm wavelength has been used to induce plasma of copper and zinc samples. The experimental parameters of laser energy, ICCD gate width and gain, entrance slit of spectrometer were fixed as 40 mJ, 100 ns, 0.1 mm and 100, respectively. Then the effects of physical and chemical characteristics of metal samples on the optimal experimental parameters such as the distance from the focal point of the converging lens to the sample surface, ICCD acquisition delay and so on were studied. In the experiment, Cu(I)521.82 nm and Zn(I) 481.053 nm spectral lines were selected as LIBS signals respectively. The intensities of LIBS signal at different distances of the lens focus from the sample surface were measured. It was shown that the largest singals are appeared at 5 mm and 5.5 mm distances from the focal point to the surface of copper and zinc samples, respectively. The optimal ICCD gate delays for copper and zinc are 1300 ns and 1100 ns with the largest signal-to-noise ratio of signal and observable intensity. The experimental results are analyzed and discussed reasonably, which provides reference for the subsequent research on the mechanism of matrix effect and nano-structure enhancement of laser-induced breakdown spectroscopy for metal samples.