研究了基于一台皮秒Nd∶YAG激光器实现合金样品的双脉冲激光剥离-激光诱导击穿光谱（LA-LIBS）微损元素分析。 实验采用低能量的532 nm二倍频激光烧蚀并剥离出微量样品, 然后采用较高能量的延时1064 nm激光对剥离出的样品进行二次激发, 以增强等离子体中的原子辐射强度和提高光谱检测灵敏度。 实验分别研究了烧蚀激光脉冲和二次激发光脉冲的能量对信号强度的影响。 在烧蚀激光脉冲能量为10 μJ, 二次激发光脉冲能量为2.5 mJ的条件下, LA-LIBS中Cu Ⅰ 324.75 nm原子谱线的强度与单脉冲LIBS相比改善了86倍, 激光烧蚀坑洞的直径小于10 μm。 研究表明: 基于一台皮秒Nd∶YAG激光器, 采用双脉冲LA-LIBS技术可以较好地实现对固体样品的微损元素分析。 该技术在贵重样品分析和高空间分辨的二维元素显微分析中具有一定的应用价值。

A study on elemental analysis of alloy samples under low sample destruction with dual-pulse laser-ablation laser induced breakdown spectroscopy (LA-LIBS) based on one picosecond Nd∶YAG laser is presented. In LA-LIBS, low pulse energy 532 nm laser was used for sample ablation and high pulse energy, time–delayed 1 064 nm laser was used for re-excitation of the ablated samples to enhance atomic emissions of the laser-induced plasma and signal detection sensitivity. The influence of pulse energies of the ablation laser and excitation laser to the signal intensities was studied experimentally. I was observed that Cu 324.75 nm line intensity in LA-LIBS was enhanced 86 times in comparison with that obtained in SP-LIBS under 10 μJ pulse energy of the ablation laser and 2.5 mJ pulse energy of the excitation laser. The diameter of the crater generated in LA-LIBS was less than 10 μm. It is demonstrated the possibility of using dual-pulse LA-LIBS to realize elemental analysis of solid sample under low sample destruction. This technique is valuable for elemental analysis of precious samples and 2D elements mapping under high spatial resolution.