液体中Cu元素双脉冲激光诱导击穿光谱测量研究

为了研究液体中重金属元素的双脉冲激光诱导击穿光谱，文章通过双脉冲激光诱导击穿光谱(Double Pulse Laser Induced Breakdown Spectroscopy)技术，对竖直流动的CuSO4水溶液样品中Cu元素激光诱导击穿光谱的特性进行测量和分析。实验中使用两台532nm Nd:YAG激光器作为激发光源，等离子体信号通过光栅光谱仪和CCD进行采集。实验考察DP-LIBS积分延时、激光脉冲间隔等参数对LIBS信号的影响。研究结果表明Cu元素双脉冲激发时的等离子体特征谱线发射强度是单脉冲激发时特征谱线发射强度的2倍左右，信噪比约为3.3倍，当两束激光脉冲间隔2~3μs时，谱线发射强度有最大增强，最后由定标曲线拟合结果得到Cu元素在双脉冲检测限为9.87mg/L，比单脉冲LIBS提高了约6倍，实验结果为双脉冲LIBS技术应用于水体中重金属快速检测提供了依据。

Analysis of Cu in liquid jet using Double Laser Induced Breakdown Spectroscopy

In order to study the heavy metal elements in liquid by double pulse laser induced breakdown spectroscopy, double pulsed laser induced breakdown spectroscopy(DP-LIBS) was used, the LIBS characteristics of Cu elements in a vertical flow of aqueous solution of CuSO4 were measured and analyzed. Two Q-switched Nd:YAG lasers operating at 532nm was utilized to generate plasma on a flowing liquid surface, and plasma signal by detecting the CCD grating spectrometer. The experiment investigated gate delay, the delay time between two lasers of DP-LIBS. The results show that the intensity and SNR of Cu emission lines excited by double pulse is about 2 and 3.3 times than the intensity of line emission excited by the single pulse separately. When the delay time between two lasers at 2~3μs, emission line intensity reached maximum enhancement. The detection limit of metal ion in water solution under the optimized operation conditions was found to be 9.87mg/L for Cu, which is about 6 times than single pulse.