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为了确定激光诱导击穿光谱(1aser-induced breakdown spectroscopy,LIBS)的最佳探测时间,采用时间分辨LIBS研究了样品中4种元素Fe、Pb、Ca和Mg的4条特征谱线峰值强度以及相应的连续背景辐射光谱强度的衰减特性,对特征谱线峰值强度和连续背景辐射光谱强度的比值求极值,获得了特征谱线最佳信背比(signal-to-background ratio,SBR)所对应时间的计算值。连续背景辐射和特征谱线光谱强度均呈指数形式衰减,4条特征谱线衰减时间分别为1.42,1.95,1.69,1.65μs,相应的连续背景辐射衰减时间分别为0.85,0.93,0.89,0.87μs。4条特征谱线最佳SBR所对应时间的计算值分别为1.43,1.77,1.62,1.80μs,最佳SBR所对应的时间的实验测量值分别为1.5,2.0,1.5,1.5μs,二者具有较好的一致性.特征谱线峰值强度和连续背景辐射光谱强度的演化规律能够对最佳SBR出现的时间作出预测.以上研究结果表明,LIBS最佳探测时间与连续背景辐射和特征谱线的衰减规律密切相关,通过对光谱强度的比值求极值,可以预测谱线最佳SBR出现的时间,此方法为确定LIBS技术探测和分析的最佳时间提供了依据.
In order to determine the optimal detection time of laser-induced breakdown spectroscopy (LIBS), the time-resolved LIBS was used to study the peak intensities of the four characteristic lines of Fe, Pb, Ca and Mg in the samples, , And the ratio of the peak intensity of the characteristic spectrum to the spectral intensity of the continuous background radiation was calculated to obtain the optimal value of the signal-to-background ratio (SBR) of the characteristic spectrum The calculated value of time. The spectral intensity of continuous background radiation and characteristic spectrum both attenuated exponentially, the decay time of four characteristic lines were 1.42,1.95,1.69 and 1.65μs, respectively, and the corresponding continuous background radiation decay time was 0.85,0.93,0.89,0.87μs . The calculated values corresponding to the optimal SBR for the four characteristic lines were 1.43, 1.77, 1.62 and 1.80 μs, respectively, and the experimental measurements of the time corresponding to the optimum SBR were 1.5, 2.0, 1.5 and 1.5 μs, respectively, Better consistency.The evolution law of the peak intensity of characteristic spectrum and the intensity of continuous background radiation can predict the optimal SBR occurrence time.The above results show that the best detection time of LIBS and the continuous background radiation and characteristic spectral line Attenuation law is closely related to the spectral intensity ratio by the extreme value, you can predict the best SBR spectrum appearance time, this method to determine the best time to detect and analyze LIBS technology provides the basis.