激光诱导击穿光谱定量分析玉石中的Mg,Fe和Ca

摘要

基于对样品进行的激光诱导击穿光谱和 X射线荧光光谱分析测试建立了天然玉石中主要元素 Mg , Ca和微量元素 Fe的定标曲线。实验采用纳秒级的 Nd∶YAG激光器(波长：1064 nm)为光源,在延迟时间为3μs,激光脉冲累积数量为110,单个脉冲能量为100 mJ,脉冲重复频率为10 Hz的实验条件下,采用激光诱导击穿光谱技术装置对天然南阳独山玉石样品中的元素进行等离子体激发测试,得到波长在300~1000 nm的等离子光谱图。通过将得到的光谱图中特征峰与美国国家标准与技术研究院数据库进行对比,发现测试样品中含有 Mg,Fe和Ca等元素,以 X射线荧光光谱分析技术对四种南阳独山玉标准样品中测量出的Mg,Fe和Ca元素氧化物含量作为标准数据,选取含量比较高的Al元素作为内标元素,采用内标法对玉石光谱图中 Mg,Fe和Ca元素特征峰值进行线性拟合,从而得出 Mg,Fe和Ca三种元素的定标曲线,求出待测样品中这3种元素氧化物的含量,结果表明这三种元素氧化物的含量与中国珠宝宝石收藏鉴赏全集资料中所给出的元素氧化物含量的百分比范围 MgO (0.28%~1.73%),Fe2 O3(0~0.8%),CaO (18%~20%)相符合,相比于常用的方法,激光诱导击穿光谱技术可以快速地对待测样品进行检测,样品预处理简单且对样品损害较小。进一步验证了激光诱导击穿光谱技术对于玉石应用的可行性。%Based on laser induced breakdown spectroscopy and X-ray fluorescence spectroscopy,The calibration curve of the main elements Mg,Cr and trace element Fe in the Jade samples is obtained based on experimental results.In the experiment, LIBS experiment conditions were 3μs delay,110 accumulated laser pulse,100 mJ·pulse-1 ,10 Hz pulse repetition frequency, plasma in Nanyang jade was induced using nono-second Nd∶YAG (wavelength:1 064 nm)laser as the excitation source in the atmosphere envtronment of the laboratory.The spectral lines in the 300~1 000 nm wavelength range have been identified with the laser-induced breakdown spectroscopy.Through comparing the characteristic spectrum with the National Institute of stand-ards and Technology Research Institute (NIST)database,the element of Mg,Ca and Fe are found in the Jade samples.Using the X-ray fluorescence spectra analyzed the metal elements Mg,Cr and Fe in Nanyang standard jade and obtained the content of elemental oxides,taking the content as standard data and selecting the high content element Al as internal standard element. According to LIBS calibration curve,we can calculate the content of 3 elements in the measured sample.The result shows that the concentration of elements locate in their corresponding standards range,for example,go(0.28%~1.73%),and Fe2 O3 (0~0.8%),CaO (18%~20%).Because of its unique features,like the absence of sample preparation,the ability to perform real-time,and in situ analysis as well as the quasi non-destruction and micro-analysis character of the measurements,so as to verify the feasibility of LIBS application in j ade.