为了提高激光诱导击穿光谱(laser induced breakdown spectroscopy,LIBS)实验装置检测赣南脐橙中重金属元素的检测灵敏度和稳定性,可对检测参数进行范围设定.在初次选定延迟时间参数值后,再在包含初定延迟时间的1.10～1.30μs范围内细分进行实验.实验得出:在该范围内,延迟时间与信背比和被测元素特征谱线强度的关系曲线上出现了多个峰值,并且这些峰值都比初次的要大,用统计学中的区间估计间接求出延迟时间的置信区间为[1.13,1.25],在置信区间内延迟时间由初定的1.20 μs调至1.14 μs时,相对标准偏差(RSD)由0.103降到0.025.由此表明:设定一个LIBS实验装置的参数范围,在对待测元素检测时可以在这一范围内进行自由调节来提高其检测的精度和灵敏度.%In order to improve the precision and sensitivity of laser-induced breakdown spectroscopy device on detecting heavy metal, parameter optimization should be done. After selecting the initial delay time parameter in detecting navel orange experiment of laser-induced breakdown spectroscopy device, a cell range from 1. 10 to 1. 30 μs of delay time containing the initial parameter was extracted and experiment on it was conducted. There are more than one peak in the curve of element line intensity and signal-to-background ratio vs the delay time in the cell range, and the peak values are higher than the initial one. Confidence interval of the delay time calculated indirectly by interval estimation in Statistics is (1. 13, 1. 25]. The relative standard deviation decreases from 0. 103 269 548 to 0. 025 322 279 5 when the delay time adjusted from 1. 20 to 1. 14 μs in the confidence interval. It is suggested that parameters range of LIBS experimental device can be adjusted freely in the range while detecting measured elements so as to improve the precision and sensitivity.
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