为了提高激光诱导击穿光谱的质量, 采用高能量铷玻璃脉冲激光烧蚀土壤样品, 由组合式多功能光栅光谱仪和CCD探测器等组成的光谱分析系统记录光谱信息, 研究了有或无CsCl样品添加剂时多个激光脉冲作用于土壤样品同一位置条件下, 每个激光诱导等离子体辐射强度的变化情况, 并通过Boltzmann图方法测量了等离子体的电子温度。实验结果表明, 随着激光脉冲序数的增大, 等离子体辐射逐渐增强。计算可知, 对于含有15%CsCl的样品, 第6个激光脉冲等离子体中元素Fe、Mn、K和Ti的谱线强度比第2个激光脉冲的分别提高了3.59、2.46、2.82和1.62倍; 光谱信噪比分别提高了3.03、1.97、2.28和1.40倍; 而第6个激光脉冲等离子体的温度比第2个的升高了5 360 K。

To improve the spectral quality of the laser- induced breakdown spectroscopy, soil samples are ablated by a high-energy neodymium glass pulse laser. Plasma spectra are recorded by the laser spectrum analytical system composed of a multi-functional grating spectrometer acquisition system and a CCD. The change of the laser-induced plasma radiation intensity is researched under the condition of multiple laser pulse to ablated the same position of soil sample with or without CsCl additives, and through the Boltzmann-figure way to measure the plasma temperature. The experimental results indicated that the plasma radiation gradually strengthened with the increasing of the laser-pulsed number. The calculating results show that for the soil sample with 15% CsCl additive, the spectral lines intensity of element Fe, Mn, K and Ti in sixth laser pulse plasma increased around 3.59,2.46,2.82 and 1.62 times than that in the second one respectively ; spectral signal-to-noise ratio increased about 3.03、1.97、2.28 and 1.40 times respectively; and the electron temperature of plasma went up 5360 K than that in the second laser pulse plasma.