环境气体对于激光诱导等离子体的形成和演化特征有着重要影响,适当的环境气体条件有利于激光诱导等离子体发射光谱分析的进行。利用准分子激光(308 nm)烧蚀低合金钢靶诱导等离子体原子发射光谱,研究了环境气体对等离子体发射光谱强度及时间演化特性的影响,对实验结果进行了讨论,得到了激光诱导Fe等离子体的原子发射光谱分析的优化条件。实验测定了不同气压氩气、氦气环境下及真空条件下Fe等离子体发射光谱强度及时间演化特性。结果表明,环境气体对激光诱导Fe等离子体发射光谱具有增强作用,而在较低气压下氩气比氦气的辐射增强效果更为显著。在5.32×104 Pa氩气环境下,在等离子体形成后约6 μs和10 μs时发射谱线强度和信号背景比分别达到最大值。

Effects of ambient atmosphere on the emission characteristics of laser-induced Fe plasma are studied with a XeCl excimer laser. The experimental results are discussed briefly on the basis of temporal observations of the emission characteristics. The conditions for maximum spectral line intensity and signal-to-background ratio are defined. The time-resovled emission spectra of laser-induced Fe plasmas with Ar, He as ambient gases at different pressure and in vacuum are measured. The experimental results show that the ambient atmosphere has an enhancement effect on the emission intensity of the laser-induced Fe plasmas, and Ar atmosphere has more enhancement effect than He atmosphere at reduced pressure. The maximum spectral line intensity and signal-to-background ratio are attained in 6μs and 10μs respectively after the formation of the plasmas in Ar atmosphere with pressure of 5.32×104 Pa.