基于光电倍增管的时间分辨激光诱导击穿光谱分析系统

基于光电倍增管(PMT)设计了光谱检测系统,采用多路模拟开关控制积分电路与激光脉冲同步光谱采集,可以精确控制延时时间和积分时间,实现了时间分辨的光谱采集。通过应用于激光诱导击穿光谱(LIBS)系统,对碳钢中C、Si、Mn、Cr、Ni、Cu等元素采用时间分辨和连续积分两种模式采集光谱进行对比分析,可以有效地提升信噪比,并降低检出限,这为LIBS技术应用于微量元素分析提供了一种低成本实现方法,也为LIBS在各领域的推广应用提供了更多选择。     

Quantitative analysis of C,Si, Mn,Ni, Cr and Cu in low-alloy steel under ambient conditions via laser-induced breakdown spectroscopy

A diode-pumped solid-state laser(DPSSL) with a high energetic stability and long service life is applied to ablate the steel samples instead of traditional Nd:YAG laser pumped by a xenon lamp,and several factors, such as laser pulse energy, repetition rate and argon flow rate, that influence laser-induced breakdown spectroscopy(LIBS) analytical performance are investigated in detail.Under the optimal experiment conditions, the relative standard deviations for C, Si, Mn, Ni, Cr and Cu are 3.3%–8.9%, 0.9%–2.8%, 1.2%–4.1%, 1.7%–3.0%, 1.1%–3.4% and 2.5%–8.5%,respectively, with the corresponding relative errors of 1.1%–7.9%, 1.0%–6.3%, 0.4%–3.9%,1.5%–6.3%, 1.2%–4.0% and 1.2%–6.4%. Compared with the results of the traditional spark discharge optical emission spectrometry technique, the analytical performance of LIBS is just a little inferior due to the less stable laser-induced plasma and smaller amount of ablated sample by the laser. However, the precision, detection limits and accuracy of LIBS obtained in our present work were sufficient to meet the requirements for process analysis. These technical performances of higher stability of output energy and longer service life for DPSSL, in comparison to the Q-switch laser pumped by xeon lamp, qualify it well for the real time online analysis for different industrial applications.