光谱学与光谱分析, 2017, 37 (2): 588, 网络出版: 2017-06-20
单脉冲和再加热正交双脉冲激光诱导击穿光谱对比研究
Comparative Study on Laser Induced Breakdown Spectroscopy Based on Single Pulse and Re-Heating Orthogonal Dual Pulse
激光诱导击穿光谱 正交双脉冲 谱线增强 信背比 等离子体温度 电子密度 Laser-induced breakdown spectroscopy Orthogonal dual-pulse Spectral enhancement Signal-to-background ratio Plasma temperature Electron density
摘要
为了提高激光诱导击穿光谱技术(LIBS)的检测灵敏度和辐射光谱特性, 采用再加热正交双脉冲结构对样品中的4种元素Fe, Pb, Ca和Mg以及含有不同浓度重金属元素Cr的土壤样品进行分析。 研究了4条特征谱线FeⅠ: 404581 nm, PbⅠ: 40578 nm, CaⅠ: 42267 nm和MgⅠ: 518361 nm的光谱强度和信背比随两激光脉冲之间时间间隔的变化关系, 获得了两激光脉冲之间最佳的时间间隔为10 μs。 在单脉冲和双脉冲条件下, 得到了4条特征谱线FeⅠ: 404581 nm, PbⅠ: 40578 nm, CaⅠ: 42267 nm和MgⅠ: 518361 nm光谱强度的增强倍数分别为223, 231, 242和210; 分析了特征谱线FeⅠ: 404581 nm和CaⅠ: 42267 nm谱线强度随时间的演化特性以及4条特征谱线信背比随光谱采集延时的变化关系, 双脉冲能有效延长光谱强度的衰减时间以及提高特征谱线的信背比; 比较分析了等离子体温度和电子密度随时间的演化特性, 在双脉冲条件下, 等离子体温度最大升高了730 K, 电子密度最大增加了18×1016 cm-3。 单脉冲和双脉冲条件下获得重金属元素Cr的检测限分别为38和20 μg·g-1, 再加热正交双脉冲技术使元素检测限下降近2倍。 以上结果表明: 再加热正交双脉冲能有效地提升LIBS技术的检测灵敏度和光谱特性, 为进一步降低元素的检测限提供了有效的方法。
Abstract
In order to improve the detection sensitivity and spectral characteristic of laser-induced breakdown spectroscopy (LIBS), re-heating orthogonal dual-pulse configuration is adopted to analyze Fe, Pb, Ca and Mg contained in the sample and soil sample contained different concentrations of heavy mental Cr. Variation relationship between spectral intensity, signal-to-background(SBR) of four characteristic spectral lines FeⅠ: 404581 nm, PbⅠ: 40578 nm, CaⅠ: 42267 nm and MgⅠ: 518361 nm and time interval of two laser pulses is discussed, the best time interval of two laser pulses is obtained 10 μs. In the condition of single pulse and dual-pulse, the enhancement factor of spectral intensity of four characteristic spectral lines FeⅠ: 404581 nm, PbⅠ: 40578 nm, CaⅠ: 42267 nm and MgⅠ: 518361 nm is respectively 223, 231, 242 and 210; The time evolution characteristic of spectral intensity of characteristic spectral lines FeⅠ: 404581 nm and CaⅠ: 42267 nm is considered, and also the variation relationship between spectral acquisition delay time and SBR of four characteristic spectral lines, dual-pulse can prolong decay time of spectral intensity and improve the SBR of characteristic spectral lines; time evolution characteristic of plasma temperature and electron density is compared in the condition of single pulse and dual-pulse, maximum elevation of plasma temperature is found to be 730 K, and the maximum increase of electron density is 18×1016 cm-3. The limits of detection of heavy mental Cr are obtained 38 and 20 μg·g-1 respectively in condition of single and double pulse, limit of detection of Cr is reduced approximately 2 times by the condition of re-heating orthogonal dual pulse. Results above indicate that re-heating orthogonal dual-pulse can improve detection sensibility and spectral characteristic of LIBS technique, which provides an effective method for decreasing the limit of detection of elements.
余洋, 赵南京, 方丽, 孟德硕, 谷艳红, 王园园, 贾尧, 马明俊, 刘建国, 刘文清. 单脉冲和再加热正交双脉冲激光诱导击穿光谱对比研究[J]. 光谱学与光谱分析, 2017, 37(2): 588. YU Yang, ZHAO Nan-jing, FANG Li, MENG De-shuo, GU Yan-hong, WANG Yuan-yuan, JIA Yao, MA Ming-jun, LIU Jian-guo, LIU Wen-qing. Comparative Study on Laser Induced Breakdown Spectroscopy Based on Single Pulse and Re-Heating Orthogonal Dual Pulse[J]. Spectroscopy and Spectral Analysis, 2017, 37(2): 588.