Detection of Metal Ions by Quenching of Dye Laser Emission

A novel laser intracavity method for detecting metal ions is described in which a metal analyte is added directly to a dye ligand and the dye laser emission is monitored as a measure of the analyte's concentration. The technique is both sensitive and selective and may have applications as an indirect probe of chemical analysis and of energy transfer.     

A Heuristic Analysis of Quantum Noise Quenching in the Two-Photon Correlated Emission Laser

We demonstrate how the two-photon correlated emission laser (CEL) can be understood from a simple physical picture in a quasirigorous fashion. We use semiclassical arguments to derive correct expressions for the phase and amplitude diffusion in a simple way. We then illustrate how noise suppression is achieved in the two-photon CEL.     

The Intra-cavity Mode Competition and Laser Absorption Spectroscopy with CO2 Laser

A mathematical model is developed for analysis the dynamics of an intra-cavity laser spectroscopy and mode competition using the CO₂ laser as the coherent source. The governing equations of system are derived and effect of the absorbing material on the laser modes, as a time-dependent term is considered. Thus, the application of the CO₂ laser for intra-cavity laser spectroscopy with considering an inhomogeneous medium and effect of the absorbing material is investigated.     

傅立叶变换激光腔内吸收光谱方法研究吸收谱线的强度与线形

在原有傅立叶变换激光腔内吸收光谱实验装置的基础上,利用信号差分方法减少了光强波动对实验干涉谱图的影响,改善了信噪比.通过对大气中氧气在760nm处的吸收谱线的绝对强度测量,验证了该方法的定量测量能力.在不同压力条件下对磷烷v=6伸缩局域模泛频吸收谱带进行了测量,获得了其谱线的自压力加宽和自压力线移参数.     

液态电极等离子体发射光谱技术检测金属离子的研究应用

快速准确的金属离子检测是涉及多个学科领域及检测技术的研究课题,文章综述了液体电极等离子体发射光谱技术在金属离子检测领域的研究及应用。首先介绍了基于电化学原理的电极法,包括离子选择性电极及阳极溶出法,及基于原子吸收或发射光谱等检测金属离子常用方法技术的原理及优缺点;然后阐述了基于等离子体的液体电极光谱技术的原理及特点,包括等离子体的产生机理、光谱特点以及其检测技术的优势;并按照液态电极数目及放电系统结构分成单液态电极及双液态电极放电系统两类,重点介绍了液态电极发射光谱技术的发展历程及研究进展,其中详细说明了ELCAD、SCGD、LS-APGD及毛细管放电等电解质放电系统的结构及特点;利用液态电极等离子体发射光谱技术,对铜、汞、银等重金属以及钠、钾、镁等活泼金属离子的检测限可达μg·L-1。最后探讨了该技术应用于检测金属离子的优势及存在的问题,并展望了其应用前景。     

Detection Of 2,4-Dichlorophenoxyacetic Acid in Reverse Micelles AOT/n-Octane by Polarization and Quenching Fluoroimmunoassays

Two fluoroimmunoassays for detection of 2,4-dichlorophenoxyacetic acid (2,4-D) in an apolar organic solvent, reverse micelles of Aerosol OT in n-octane, are proposed. Both assays are homogeneous methods, meaning that no separation of free and bound fraction of analyte and no washing steps are required. To perform the assay just add the fluorescein-labeled 2,4-D (FD) and monoclonal antibody to the sample and measure the analytical signal on the Abbott TDx Analyzer. The binding of antibodies to FD can be detected by the decrease in fluorescence intensity and also by the increase in fluorescence polarization. The sensitivity of the developed methods was strongly dependent on the micellar matrix (micellar hydration degree and surfactant concentration). The detection limits of 2,4-D in optimal reverse micellar medium are 0.10 g/L (polarization method) and 0.12 g/L (quenching method). These sensitivities are significantly better compared to the detection limits in an aqueous medium, 0.6 and 0.4 g/L, respectively, using the same reagents.     

Investigation of Ancient Chinese Potash Glass by Laser Ablation Inductively Coupled Plasma Atomic Emission Spectroscopy

In the present study, laser ablation inductively coupled plasma atomic emission spectroscopy (LA-ICP-AES) was successfully used to classify 26 ancient potash glass beads. These samples, mainly dated from the Han Dynasty to the Jin Dynasty, were from several provinces of both China and Vietnam. Quantitative analyses were done with both weathered and polished samples in order to consider the effects of surface weathering. Based on the characteristics of major, minor, and trace elements, we divided the samples into three subgroups (the percentage for each subgroup was 50%, 42%, and 8%, respectively) and also determined their main colorants. The results obtained provide new clues to trace the possible producing centers of ancient potash glasses in Asia. This study also reveals a complex network related to the trade of ancient potash glasses.     

The Application of Photon Counting as a Detection System in Atomic Fluorescence and Emission Spectrometry

Despite the profusion of literature associated with analytical atomic spectrometric techniques, very little has been reported concerning the development of detector systems. This is particularly surprising in view of the current trend in atomic spectrometry towards the use of non-flame atom reservoirs. These devices frequently produce weak transient signals and dc level detector systems designed for steady state measurements are in consequence often unsatisfactory. High speed recorders may be used with success providing the total response time of the various electronic components is comparable with or preferably less than that of the signal duration and only in such instances will precise measurement of the signal be achieved (1,2). The use of absolute integration techniques are obvious for this type of measurement, although their application has not been particularly forthcoming to date. Photon counting would seem to have many advantages for such purposes, although with the exception of the more general studies of Morton (3) and Malmstadt and co-workers (4) it has received so far little consideration. Indeed its use as a detection system in analytical atomic fluorescence and emission spectrometry has yet to be reported.     

ICP-AES-CID二维光谱的频率特性研究

本文对电感耦合等离子体原子发射光谱分析（ICP－AES）中电荷注入检测器（CID）得到的二维光谱的频率特性作了研究。测量光谱经过傅里叶变换得到其光谱的频率分布。结果表明,测量光谱在频域中的信号可被分为两部分：即低频信号和高频信号。前者代表有用的分析信号而后者代表背景和噪声。然而,不能采用简单滤除高频信号的方法来去除噪声,因为这样虽然高频信号没有明显改变但会使背景变形。     

Sample Input Modulation and Lock-in-Amplifier Detection for Signal-to-Noise Ratio Improvement in Inductively Coupled Plasma Atomic Emission Spectroscopy

The effect of modulation of the sample atomization, accomplished by pulsing the nebulizer pump, and lock-in-amplifier (LIA) detection of the modulated output signal of an ICP atomic emission spectrometer is studied. The time constant of the nebulizer spray chamber allows a maximum modulation frequency of approximately 2 Hz, but optimum performance for this system is found at a modulation frequency of approximately 1 Hz. A signal-to-noise (SNR) ratio improvement approaching a factor of three is found for the arrangement employed. It is proposed that more rapid modulation, achievable through the use of a nebulization system with a shorter time constant, should lead to even greater improvement in the SNR than was accomplished in this study. The dynamic range is improved, relative to the unmodulated system, as the detection limit is lowered without any loss of linearity at high concentrations. A linear dynamic range of greater than 4 orders of magnitude is found for the modulated system.     

Use of Organic Solvents as Additives in Inductively Coupled Argon Plasma with Atomic Emission Spectrometric Detection

Abstract

The effect of nitric acid/organic aerosols on the emission intensity of metals from the first row transition series, plus Cd and Pb was investigated. The addition of organic solvents to reference solutions diminished the aerosol mean drop size, by reducing the surface tension of the solutions. Correlation between signal intensity and BEC with the main physical characteristics (surface tension and viscosity) of the nitric acid/acetic acid and nitric acid/alcohol solutions was studied. Analytical curves (0–2.0 fig ml^?1) were evaluated using a matrix matching procedure, and detection limits indicated an improvement (ca 40%) in analytical performance as well as in linearity, sensitivity and precision.     

奶牛场氨排放特征的光谱检测

为实现奶牛场氨气减排,改善生态环境,需要在线监测氨挥发浓度并准确揭示氨排放特征。采用开放式可调谐半导体激光吸收光谱 (TDLAS) 技术设计了开放式氨气在线监测系统,结合反演式气体扩散技术开展相关研究,于2013年秋季和冬季在保定市某奶牛厂进行了氨排放浓度在线监测和排放特征分析工作。监测结果表明,秋季氨气浓度峰值为6.11×10-6%,冬季氨气浓度峰值为6.56×10-6%,氨浓度具有日变化趋势,基本呈白天浓度低,夜晚浓度高的特点。由反演气体扩散模型得到秋冬季氨排放特征,氨排放峰值均出现在中午,秋季氨排放速率为1.48～130.6 kg/head/hr,冬季氨排放速率为0.004 5～43.32 kg/head/hr,秋季的排放速率高于冬季,说明奶牛场尺度下的氨排放存在一定的季节性差异。该方法可以有效获得大范围、高灵敏、免采样、快速气体排放特征结果,为奶牛厂的氨排放监测和科学养殖提供技术支持。     

荧光发射强度影响因素及荧光猝灭实验研究

荧光发射强度在荧光显微术科学观测中至关重要。理论分析了三大影响荧光发射强度的重要因素:分子吸收激发光光子的能力、荧光量子产量及其荧光饱和与荧光猝灭,指出选择具有大光吸收截面和高量子产量的荧光分子,能有效保证荧光发射强度;确定合理的激发光强度范围,可避免不必要的荧光饱和现象。进一步实验研究了超高真空和大气环境下的荧光猝灭现象,得出超高真空时荧光分子的荧光猝灭现象极不明显,而大气环境可造成荧光光强指数递减的结论。     

氢原子谱线与高质量金刚石薄膜

采用蒙特卡罗方法,对以CH₄/H₂混合气体为源气体的电子助进热丝化学气相沉积(EACVD)中的氢原子发射过程进行了模拟。在模拟中考虑了电子与H₂的弹性碰撞及振动激发、分解、电子激发(包括H_α, H_β, H_γ谱线的激发)、电离及分解电离等非弹性碰撞过程;与CH₄的碰撞考虑了弹性动量传输及振动激发、分解、电子激发、分解激发(包括H_α, H_β, H_γ谱线的激发)、电离及分解电离等非弹性碰撞过程。研究了不同实验条件下产生的H, CH₃的数目与氢原子谱线相对强度的关系,给出了一种利用氢原子谱线来获得最佳成膜实验条件的方法。对于有效控制工艺条件,生长出高质量的金刚石薄膜具有重要意义。     

Fluorescence and Laser Emission from Coumarin-Acridine Orange Mixtures

The sensitized fluorescence and laser emissions of dye mixtures; (I) coumarin 102 (donor) and acridine orange (acceptor) and (II) coumarin 47 (donor) and acridine orange (acceptor) with Hg-lamp and N₂ laser, have been measured as a function of dye concentration and of the pump power (N₂ laser). Acridine orange which does not lase by itself on excitation with N₂ laser, lases efficiently in the presence of 7-amino-coumarins via singlet-singlet energy transfer. Energy transfer rate constants and critical distances have been estimated from fluorescence intensity and lifetime measurements. The performance of energy transfer dye lasers (ETDLs) are discussed in terms of spectral characteristics of the dyes and their penetration depths.     

Cs 728 nm Laser Spectroscopy and Faraday Atomic Filter

The laser spectroscopy of alkali-metal vapor is widely used in a number of applications, such as the Faraday anomalous dispersion optical fil- ter （FADOF）, the active optical clock, and wavelength references.Is＇ The Cs electrodeless dis- charge vapor lamp has rich spectra, including 455 nm, 459 nm, 728 nm, 852 nm, 1359 nm, and 1470 nm. The 852 nm laser pumping atoms from 6S1/2 to 6P3/2 have been used in FADOF.The 1359nm wave- length transited from 7S1/2 to 6P1/2 of Cs atoms can be used in the field of active optical clocks. The concept of active optical clocks has been proposed since 2005. Due to its good performance in sta- bility, the active optical clock has been extensively in- vestigated theoretically and experimentally in recent years, such as the two-level active optical clock, and three-level active optical clock. When considering the performance of the active optical clock, we hope to reduce the second-order Doppler shift in thermal atomic beam and the light shift induced by the pump- ing laser. To solve this issue, our group has recently proposed a four-level active optical clock, such as K 1252.2nm, Cs 1469nm, Rb 1366.9nm and Rb 728 nm. Moreover, the Rb 728 nm four-level quantum system has potentially a better performance than three long wavelength ones of Rb.     

Relation Between Laser Induced Infrared Fluorescence and Laser Absorption By Pollutant Gases

Symmetry coordinates were developed for the dodecaborane-ion type X₁₂Y¹² model of symmetry I_h. Two sets of force constants for the ion are reported, where it was made use of Decius' and Keating's bendings, respectively. Calculated frequencies for B₁₂H₁₂ and B₁₂D₁₂ are compared with observed data. Better agreement was obtained for the set with Keating's bendings. This conclusion is consistent with one of a previous normal coordinate analysis.     

Development of a Two-Dimensional Bar-Code Detection System Using Multi Laser Diodes with Time-Sharing Light Emission Operation

A new high-speed two-dimensional bar-code detection system using multi laser diodes with time-sharing light emission operation has been developed. A bias current allowing the laser diode to improve the light output rise time was optimized to slightly below the threshold of the diode, so that channel cross-talk among three-line bar-code signals caused by the bias light can be kept small and a high-speed pulse modulation operation can be achieved. The prototype system for a three-line bar code with spatially overlapping laser-diode heads has achieved an effective scanning speed two and nine tenths times that of conventional scanners. It is estimated that the number of time-sharing light emission laser diodes can be increased to at least four when the current photodetection amplifier with a bandwidth of 6.4 MHz is used. This number can be improved to six by using photodetection amplifiers with double the bandwidth of the present ones.     

发射光谱法测定乳浊料中的锆和铪

研究了用碳粉和二氧化钛作缓冲剂同时测定乳浊料中的锆和铪的发射光谱法,选择钛作内标线,不需分离、不需化学处理,直接压样于杯形的石墨电极中,具有简便、快速、准确的特点。对测定条件、干扰因素进行了研究,从而建立测定锆和铪的新方法。锆和铪的分析线分别为327.3和286.6 nm,内标线选择为钛的308.8 nm线,锆和铪的线性范围分别为0～0.50%和0～0.25%。锆和铪的检测限分别为0.001%和0.010%,其回收率为96.67%～105.0%,当n=9时,锆的RSD为3.61%;铪的RSD为4.82%;用于样品的测定取得了满意的结果。     

原子发射光谱法测定镁砂中的硅和铁

镁砂是生产烧结焊剂的重要原料。本文采用原子发射光谱分析法，通过加入合金的缓冲剂，并选择合理的内标，成功地对镁砂中的硅和铁进行了测定。