Nucleation and growth of silver nanoshells through copper vapor laser irradiation

Silica core–silver shell, silver nanoshells (NSs), have been synthesized by an innovative laser-based approach. The NSs’ nucleation and growth progressed upon the pulse strikes of a copper vapor laser on a colloidal solution containing silver and silica nanoparticles (NPs). The silver NPs were separately synthesized by ablation of a silver target in deionized water by a 1064 nm Q-switched Nd:YAG laser. The dependence of silver NSs’ growth on the laser exposure time has been systematically studied by UV–VIS absorption spectroscopy technique. Transmission electron microscopy was exploited as well to visually confirm the NSs’ evolution through the process.     

激光诱导击穿光谱自吸收效应校正方法的研究进展

激光诱导击穿光谱作为一种新型的物质成分检测技术,具有快速、实时、微损、原位、多元素同时分析等优势,目前在环境监测,食品安全,选矿冶金,生物医疗,太空探测等多个领域都具有广泛应用.然而,由于元素谱线的自吸收效应,使得激光诱导击穿光谱谱线强度降低,严重时甚至会使特征谱线峰型产生凹陷(即自蚀现象),定标曲线变弯曲,导致该...     

Spectroscopic characterization of low-nickel copper welding with pulsed Nd:YAG laser

Effects of various operating parameters of 400 W pulsed Nd:YAG laser on welding of nickel-alloyed copper have been investigated. The induced plume spectra in case of using different assist gases and preheat temperatures have been analyzed and the effects of these key factors on melt features such as penetration depth, porosity and spattering have been attributed to the spectroscopic behavior of the plume. Moreover, the CuI electron temperature and its standard deviation as the spectroscopic responses of the plasma plume to various laser process parameters have been quantitatively evaluated at different average and peak powers and pulse energies. Also, the mentioned responses were utilized to justify the weld bead profile features, involving weld depth, width and their stabilities, at similar process parameters. The operating conditions of welding were optimized, regarding the results of spectroscopic observations and attributing them to the qualitative aspects of the melt pool.     

基于不同化学计量学方法的土壤重金属激光诱导击穿光谱定量分析研究

工业的发展及城市化进程的深入,造成大量耕地土壤遭受重金属污染,土壤重金属元素的准确检测对制定土壤重金属防治决策提供有效参考。本研究应用激光诱导击穿光谱(LIBS)结合化学计量学方法对土壤中的铅(Pb)和镉(Cd)元素进行定量分析。根据土壤重金属污染的不同程度,人为制作了含有Pb和Cd元素的15个浓度梯度的土壤样本,并采集各个样本的LIBS谱线。采用剔除异常光谱和数据归一化来减少试验误差和噪声。综合土壤LIBS发射谱线中Pb和Cd元素谱峰信息以及美国国家标准与技术研究院(NIST)的标准原子光谱数据库,选取了Pb,Cd元素的分析谱线与分析谱线区间,对比分析基于多元线性回归(MLR)、偏最小二乘回归(PLSR)、最小二乘支持向量机(LS-SVM)和反向传播人工神经网络(BP-ANN)算法,建立分析谱线区间与对应Pb和Cd元素浓度之间的定量回归模型。结果表明,非线性的LS-SVM和BP-ANN的模型的预测性能优于线性MLR和PLSR模型,这可能是因为非线性模型能够通过自适应较好地解决土壤基体效应的影响。研究表明,LIBS技术结合多元化学计量学方法能够为土壤重金属准确检测提供新的分析手段,为制定农业土壤重金属防治决策提供有效的理论基础。     

激光诱导击穿光谱烟叶Cu谱线等离子体参数及定量分析

农业领域中对植株元素的快速检测和实时监控十分重要。采用Nd∶YAG激光器和中阶梯ICCD光栅光谱仪获取金属元素Cu等离子体谱线。为研究激光诱导击穿光谱(laser induced break-down spectroscopy,LIBS)金属元素Cu定量分析的标定曲线和等离子体参数,制备Cu含量范围为8.59～156.35 μg·g-1烟叶样品进行实验。实验结果表明烟叶中金属元素Cu特征谱线324.75 nm处干扰小、谱线明显。烟叶样品受激发产生等离子体温度为39 458.94 K,Cu等离子体电子密度为0.74×1016,谱线强度和样品浓度建立的标定曲线相关系数r为0.98,平均相对标准偏差RSD(relative standard deviation)为2.59%,Cu含量理论最低检测限为7.72 μg·g-1,谱线信噪比(SNR)为7.86。激光诱导击穿光谱方法可以应用于卷烟生产线在线检测金属元素Cu含量和监测烟叶中金属元素Cu对烟草生长的影响。     

Recent progress on the application of LIBS for metallurgical online analysis in China

Recent progress on the application of laser-induced breakdown spectroscopy (LIBS) for metallurgical analysis particularly achieved by Chinese research community is briefly reviewed in this article. The content is mainly focused on the progress in experimental research and calibration methods toward LIBS applications for metallurgical online analysis over the past few years. Different experiment setups such as single-pulse and double-pulses LIBS schematics are introduced. Various calibration methods for different metallic samples are presented. Quantitative results reported in the literature and obtained in the analysis of various samples with different calibration methods are summarized. At the last section of this article, the difficulties of LIBS application for molten metal analysis in a furnace are discussed.     

Stability of the conditions for excitation of atomic spectra in plasma produced on exposure of copper alloys to laser radiation

We show that the temperature of plasma produced by exposure of copper-zinc alloy specimens to laser radiation changes little (within the limits of random errors) with a change in the conditions of the laser effect and chemical composition of the specimens. With use of electric discharges (a low-voltage spark), systematic changes in the temperature of the plasma are observed when the chemical composition of copper-zinc alloys changes. Institute of Molecular and Atomic Physics of the National Academy of Sciences of Belarus, 70, F. Skorina Ave., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 3, pp. 319–321, May–June, 1998.