中文摘要：

在大气环境下采用波长为800nm，脉宽为30fs的飞秒激光研究了Ni的双脉冲激光诱导击穿光谱，与单飞秒脉冲激光诱导击穿光谱相比，双飞秒脉冲在最优的双脉冲相对延时下，其信号强度增强接近10倍，实验研究了双脉冲相对延时在0～1300ps范围内不同延时对激光诱导击穿光谱信号强度增强因子的影响．整个相对延时区域可以分为三个阶段：在0～50ps区域内信号增强因子是一个持续增大的过程，在50ps左右，达到一个最大值；在50~300ps区域内，信号增强因子呈现出一个先下降后上升的过程；在300～1300ps，信号增强因子基本保持不变．

英文摘要：

Double femtosecond pulse laser-induced breakdown spectroscopy （LIBS） of nickel was investi- gated by using two 30 fs laser radiation, both at 800 nm, in the collinear configuration under ambient conditions. In comparison with the single-pulse （SP） LIBS, the signal enhancement of a nearly 10 fold was achieved with double-pulse （DP） radiations at the optimum inter-pulses delay. The influence of the interpulse delay on the LIBS signal intensity within 0～l300 ps was investigated and three temporal intervals of interaction were observed. From 0 to 50 ps, the intensity of the emission lines increases steadily and a maximum is reached at approximately 50 ps; from 50 to 300 ps, the signal enhancement factor decreases firstly and then increases; from 300 to 1300 ps, the signal enhancement factor remains constant.