Detection of multiple elements in coal samples from Bangladesh by laser-induced breakdown spectroscopy

Laser-induced breakdown spectroscopy (LIBS) was used to analyze the coal samples from the Barapukuria coal mine of Bangladesh and coal from eastern India. Besides the major elements carbon and silicon, a number of minor and trace elements, such as iron, titanium, aluminum, calcium, sodium, copper, zirconium, neodymium, ytterbium, cerium, samarium, dysprosium and gadolinium were identified. In earlier work some researchers identified the lines around 279 and 280 nm as due to Mg II rather than Yb III. The reasons for identifying these two lines as due to ytterbium in the present work are explained. The detection of multiple elements in one experiment in a commonly used fuel demonstrated the versatility and multi-elemental capability of LIBS.     

Determination of detection limits for elements in water by femtosecond laser-induced breakdown spectroscopy

We have evaluated the feasibility of using femtosecond laser-induced breakdown spectroscopy with time-resolved detection of the spectra for determination of trace concentrations of chemical elements in water. The laser plasma was generated on the surface of aqueous solutions by a single pulse from a titanium:sapphire laser (pulse duration 40 fs, pulse repetition frequency up to 1 kHz). We obtained the 3σ limits of detection (LODs) for Al, Ba, Ca, Cu, Fe, K, Mg, Na, Zn in water as 0.19, 0.08, 0.01, 0.78, 3.4, 0.006, 1, 0.0009, 2.5 mg/L respectively.     

支持向量机算法在激光诱导击穿光谱技术塑料识别中的应用研究

基于支持向量机 (support vector machines, SVM) 算法采用激光诱导击穿光谱技术对11种塑料进行了识别. 每种塑料各采集100个光谱, 其中50个光谱作为训练集, 用于建立支持向量机模型, 剩下的50 个光谱作为测试集, 用于测试所建立支持向量机模型的识别精度. 结果表明测试集550个光谱中有543个光谱识别正确,算术平均识别精度达到了98.73%. 其中有6个聚氨酯 (PU) 光谱被误判为有机玻璃 (PMMA), 原因主要是受空气中氮气的影响, 使得有机玻璃和聚氨酯两种塑料在氮元素含量上的差异不能通过N I 746.87 nm, C-N(0,0) 388.3 nm两条谱线的强度准确表征. 本结果为LIBS技术塑料分类提供了方法和数据参考. 关键词： 支持向量机 激光诱导击穿光谱 塑料识别     

溶液中金属元素的激光诱导击穿光谱

利用激光击穿光谱的方法对水溶液样品中的金属元素进行定性和定量分析。分别采用竖直喷流（口径0.5 mm）和静止液面两种样品采样模式,针对不同质量浓度的Cd,Fe,Al和Pb元素进行了检测分析并得到了其定标曲线(线性拟合相关度基本在0.99以上),初步确定了４种元素在喷流模式下的检测限为0.206 5(Cd),0.147 6(Fe),0.061 9(Al)和0.200 9(Pb) g/L;静止液面模式下的检测限为0.050 1(Cd),0.023 9(Fe),0.014 8(Al)和0.006 9(Pb) g/L。实验所得的结果为检测工业废水中金属元素的含量提供了依据。     

用激光感生击穿光谱对大气进行定量分析

研究将激光感生击穿光谱技术用于元素定量分析的可行性。利用Nd∶YAG激光器发出的激光与一个大气压下的空气相互作用产生激光等离子体，等离子体的光经单色仪分光后转化为电信号进入计算机，存储了600～800nm的等离子体光谱数据。利用自由定标模型对等离子体进行了分析。在延迟时间8μs、采样门宽0.4μs时，利用二维波尔兹曼平面得到了大气等离子体处于局部热平衡时的温度（1.62×10K）。在假设空气全部由N和O组成的条件下由自由定标模型得到了空气中氧的含量（20.75%）和氮的含量（79.25%）。试验结果与实际吻合得很好。实验证实了用激光感生击穿光谱对大气进行定量分析是可行的，为大气污染监测研究和试验工作奠定了基础。     

基于激光诱导击穿光谱的洋葱在线原位检测

激光诱导击穿光谱(Laser-induced breakdown spectroscopy, LIBS)是一种分析多元素的光学技术,可用于新鲜蔬菜的快速检测.以洋葱为例,采用LIBS对其含有的元素进行了在线原位检测.用乙酸铅溶液污染洋葱以模拟大气湿沉降的重金属污染现象,并进行重金属Pb元素检测.使用主成分分析(principal components analysis, PCA)和反向传播人工神经网络(back-propagating artificial neutral network, BP-ANN),以洋葱、大蒜、小葱为样品进行区分检测.洋葱光谱中的特征谱线包括Si、Fe、C、Mg、Al、Ca、Ti、Sr、Ba、Na、Li和K等元素,以及N、H、O的谱线和CN分子谱带.不同浓度梯度乙酸铅溶液污染的洋葱样品中都能检测出Pb元素,其相对强度与溶液浓度成比例.此外,PCA的结果表明洋葱、小葱、大蒜的区分效果明显,BP-ANN交叉验证的识别率为89.47%.结果证明LIBS在对元素进行快速分析时具有较好的识别能力,是检测新鲜蔬菜的有效手段.     

应用激光诱导击穿光谱检测土壤中的铅

应用激光诱导击穿光谱技术对模拟土壤中Pb进行快速定量分析。该模拟土壤由PbCl₂,CaCO₃,SiO₂,KBr化学纯试剂制备而成。通过实验得到信噪比随延时的增大呈先增后减的变化规律。利用实验光谱图建立了Pb含量的定标曲线。定量分析研究得到：该方法用于Pb含量定量分析的平均相对误差为8.33%,最低检测限为89μg/g。实验结果验证了激光诱导击穿光谱技术用于土壤中Pb含量测量的能力。     

共线双脉冲激光诱导击穿光谱技术检测铝合金中的Cr和Mn

采用两台波长1064 nm的调Q脉冲Nd ∶YAG激光器和多通道小型光纤光栅光谱仪,建立了一套共线双脉冲激光诱导击穿光谱分析装置。与单脉冲激光诱导技术相比,在最佳双脉冲时间延时8 μs时,Mn I 403.07 nm和Cr I 425.43 nm的光谱强度分别增加了14.3倍和17.2倍,以这两条谱线为分析线,铝合金中Mn和Cr的检测限分别由单脉冲时的73和94.5 μg/g降低至双脉冲时的3.76和4.26 μg/g,检测灵敏度提高了约20倍。     

八字门滑坡滑带土壤的激光击穿光谱探测

利用搭建的一套激光击穿光谱测量土壤样品的实验系统,对三峡坝区香溪河段八字门滑坡滑带土壤进行了探测研究。在同一纬度不同海拔高度选取了5个地点采取了土壤样品,对5个样品进行了实验测量,得到了这些土壤样品的光谱图,并对其中的Mg,Al,Si,K等元素进行了定性和定量分析。结果表明,这些元素随着海拔的降低,其含量也逐渐降低。     

八字门滑坡滑带土壤的激光击穿光谱探测

 利用搭建的一套激光击穿光谱测量土壤样品的实验系统,对三峡坝区香溪河段八字门滑坡滑带土壤进行了探测研究。在同一纬度不同海拔高度选取了5个地点采取了土壤样品,对5个样品进行了实验测量,得到了这些土壤样品的光谱图,并对其中的Mg,Al,Si,K等元素进行了定性和定量分析。结果表明,这些元素随着海拔的降低,其含量也逐渐降低。     

Quantitative analysis of ITO film by laser-induced breakdown spectroscopy

Laser-induced breakdown spectroscopy (LIBS) is an effective method for nondestructive rapid element analysis in a wide range of media in situ. We use the LIBS technique for quantitative analysis of indium tin oxide (ITO) films, which are transparent conducting materials widely used in industry. The plasma is generated by focusing a Nd:YAG laser pulse with a duration of 10 ns and a wavelength of 1064 nm onto the ITO-sample surface. We perform test experiments to define optimum values of the laser-pulse energy and the time delay between the laser pulse and the beginning of the LIBS spectra acquisition. Next, by the calibration-free Boltzmann plot method, we assess the plasma temperature and finally calculate the content of In and Sn in the test ITO specimen, and this agrees well with real concentration values.     

自由定标激光诱导击穿光谱技术在炉渣成分定量分析中的应用

采用自由定标激光诱导光谱技术(CF-LIBS)对炉渣中几种主要成分(CaO,SiO2,Al2O3,MgO)进行了定量分析.利用Nd:YAG激光脉冲在空气中烧蚀炉渣样品产生等离子体,等离子体光谱由中阶梯光栅光谱仪记录.通过几种主要元素的原子谱线和离子谱线的玻尔兹曼图,计算了等离子体的温度.利用Ca的一条谱线Stark展宽...     

铅的单脉冲LIBS定量光谱检测与比较

单脉冲激光诱导击穿光谱技术(single-shot,LIBS)是一种在国际上被广泛使用的物质及元素检测技术,具有快速、准确、无需样品制备等诸多优点.为了满足单脉冲LIBS的实验要求,实验用激光器的选取是非常重要的,它直接关系到诱导激光的强度以及脉冲宽度的大小,而这些又对实验结果产生深刻的影响.因此,选取正确的激光器,是单脉冲LIBS成功的关键.正是基于这个目的,比较了不同波长、不同激光能量的激光脉冲作用下,纯铅发射光谱的定量变化,对于单脉冲LIBS中激光器的选取有着很好的借鉴意义.     

激光诱导击穿光谱技术及应用研究进展

激光诱导击穿光谱（LIBS）技术是一种基于原子发射光谱学的元素定性、定量检测手段。本文介绍了LIBS技术的原理、应用方式、检测元素种类及检测极限;综述了该项技术在固体、液体、气体组分检测方面的技术发展,以及在环境检测、食品安全、生物医药、材料、军事、太空领域的应用进展。最后,提出了高功率、高稳定的激光光源和准确的定量分析方法是LIBS技术目前所面临的问题和挑战。     

Biomedical and environmental applicationsof laser-induced breakdown spectroscopy

Laser-induced breakdown spectroscopy (LIBS) is an emerging analytical technique with numerous advantages such as rapidity, multi-elemental analysis, minimal sample preparation, minimal destruction, low cost and versatility of being applied to a wide range of materials. In this paper, we report the preliminary observations we obtained using LIBS for clinical and environmental samples. Elemental analysis has been done qualitatively in human teeth samples which show encouraging results. It has also been demonstrated in this paper that LIBS can be very well utilized in field applications such as plastic waste sorting and recycling.     

Search for superheavy elements in monazite from beach sands of South India

Monazite minerals obtained from beach sands of South India were examined for the presence of superheavy elements with photon-induced x-ray fluorescence method. The accumulated data of a number of runs each of several days duration do not show any convincing peaks above the background at the expected locations for superheavy elements which are above the present sensitivity of detection of about 10 ppm by weight for element 126. However, some intriguing features pertaining to structures in the x-ray spectra around 27 keV were observed, which are of interest for further investigations.     

Major elements analysis in bituminous coals under different ambient gases by laser-induced breakdown spectroscopy with PLS modeling

Three major elements, carbon, hydrogen, and nitrogen, in twenty-four bituminous coal samples, were measured by laser-induced breakdown spectroscopy. Argon and helium were applied as ambient gas to enhance the signals and eliminate the interference of nitrogen from surrounding air. The relative standard deviation of the related emission lines and the performance in the partial least squares (PLS) modeling were compared for different ambient environments. The results showed that argon not only improved the intensity, but also reduced signal fluctuation. The PLS model also had the optimal performance in multi-element analysis using argon as ambient gas. The root mean square error of prediction of carbon concentration decreased from 4.25% in air to 3.49% in argon, while the average relative error reduced from 4.96% to 2.98%. Hydrogen line demonstrated similar improvement. Yet, the nitrogen lines were too weak to be detected even in an argon environment which suggested the nitrogen signal measured in air come from the breakdown of nitrogen molecules in the atmosphere.