氢化物-石墨炉原子吸收法及其应用废水中砷的测定

本文对氢化物与石墨炉原子吸收法联合这一新方法进行了研究。以NaBH_4还原产生AsH_3,随后AsH_3在600℃下分解沉积于石墨管内表面,并在2600℃下原子化。对影响沉积效率的因素:沉积温度、载气流速、还原剂和盐酸浓度等进行了探讨。干扰实验表明,对10纳克As,至少一千倍的Bi、Se、Sb,120倍的Sn,60倍的Pb不干扰测定。证实气相干扰很小是本方法优于常规氢化物原子吸收法的主要之点。方法应用于城市废水中微量砷的测定,取得了满意的结果。方法的检出限0.24ppb(3σ),相对标准偏差6.1%,回收率90-105%。     

氢化物—石墨炉原子吸收法及其应用废水中砷的测定

本文对氢化物与石墨炉原子吸收法联合这一新方法进行了研究。以NaBH4还原产生AsH3，随后AsH3在600℃下分解沉积于石墨管内表面，并在2600℃下原子化。对影响沉积效率的因素：沉积温度、载气流速、还原剂和盐酸浓度等进行了探讨。干扰实验表明，对10纳克As，至少千倍的Bi、Se、Sb，120倍的Sn，60倍的Pb不干扰测定。证实气相干扰很小是本方法优于常规氢化物原子吸收法的主要之点，方法应用于城市废水中微量砷的测定，取得了满意的结果。方法的检出限0.24ppb（3σ），相对标准偏差6.1％，回收率90－105％。     

石墨炉原子吸收光谱法测定稀土中微量铕

本文对混合稀土中微量铕的石墨炉原子吸收光谱法测定了进行了研究，比较了铕在热解涂层石墨管，普通石墨管及ＳＴＰＦ平台管中的原子化行为。用热解涂层石墨管研究了ＨＣｌ，ＨＣｌＯ４，ＮＨＯ３，Ｈ２ＳＯ４，Ｈ３ＰＯ４等对原子化的影响；研究了稀土及一些非稀土元素的干扰及其消除，基体盐类的背景吸收干扰的特征及消除方式等，最后用ＮＨ４Ｃｌ作为基体改进剂，使灵敏度达到原来的１．９倍，有效地消除了大量其他稀土元素的干扰     

ICP-MS法测钪的干扰研究及选冶尾矿中钪的直接测定

白云鄂博矿经选铁后,尾矿中钪含量可达0.05%,具有很高的开发利用价值。建立了一种操作简便、灵敏度高并能够准确测定尾矿及富铌渣中微量钪的电感耦合等离子体质谱(ICP-MS)测定方法。对仪器参数、试样处理方法、共存元素的干扰和消除方法进行了系统研究,选用铯、铊和铑作为内标元素,对非谱干扰加以校正。对质谱干扰研究表明,尾矿中的硼、硅、钙、锆和铝均可能对钪的测定造成质谱干扰,其中硼浓度较低(<100 μg·mL-1)时,对钪测定没有明显干扰,在测定条件下铝和钙的干扰较小,可以忽略。锆和硅的质谱干扰较严重,其中锆的干扰为双电荷(90Zr++)干扰,由于双电荷离子电离产率一般不高,锆含量低时干扰可忽略,锆的含量较高时,采用公式c′=0.021c_(Zr)-0.55对结果加以校正。硅的干扰为氧化物干扰,而硅氧键解离能大,硅的氧化物(28Si17O+,29Si16O+)稳定性高,且相关同位素丰度较大,在测定条件下干扰较严重,可以采用式c″=0.013c_(Si)+0.019扣除该影响。选择了四种不同的样品处理方式,结果表明采用HCl+HF+H₂SO₄混酸方法处理,标样测定结果与标准值一致,且能有效的克服硅和硼的质谱干扰,同时降低了测定液的含盐量,减小了非质谱干扰,标样回收率在97%~99%之间。标准样品及实际样品测定表明,采用ICP-MS法直接测定白云鄂博选冶尾矿中钪含量,结果准确,相对标准偏差小于5%,方法测定下限为0.000 1%。     

FAAS法测钙时磷酸根离子的干扰及消除研究

研究了用火焰原子吸收光谱法测钙时PO3- 4对钙的测定的干扰情况以及用有关方法消除PO3-4对钙干扰的效果.用La(NO3)3和EDTA单独消除PO3-4的干扰进行了实验研究,同时对有关问题作了讨论.对测定各种样品中的钙时消除PO3-4的干扰有一定的指导意义.     

石墨炉原子吸收法测定岩石和土样中的锑

本文用石墨炉原子吸收法对岩石土样中Ｓｂ的测定方法进行了研究。对工作条件、测定酸度、涂层管，共存离子的干扰与消除、回收及精密度等进行了实验。采用Ｎｉ作为基体改进剂可以消除干扰元素对Ｓｂ的影响。此方法的回收率和精密度比较满意。     

石墨炉原子吸收分析中升温速率对基体效应影响的研究

本文系统研究Pb、Cd、Be在普通石墨管,热解涂层石墨管,全热解石墨管,石墨平台和钨钽热解石墨管和各种升温速率下的干扰。通过系统研究发现,钨钽石墨管结合使用快速升温(4000—6000K/s)对消除各种基体对Pb、Cd、Be干扰效果较好,可以避免使用基体改进剂,方法简便快速。     

L’vov平台在石墨炉原子吸收分析中的应用

使用石墨炉作超痕量分析时常遇到样品基体的干扰。将样品直接置于石墨管壁时,原子化发生在一个温度分布不均匀的加热环境中,它不具有抗干扰能力。L’vov 及其他一些作者发现,如果将样品置于石墨管内的一薄片石墨平台上,则会有较大的抗干扰能力。我们对这种石墨平台技术进行了研究。为准确地记录下原子化波峰形状及波峰的出现时间,使用了高速数据收集装置和图象显示装置。通过测定几种 NBS 标准样品中的Cd 和 Pb,研究了干扰情况。有时在使用峰高测量方式时遇到的干扰影响很强,但在改用峰面积测量方式时会变得很弱。试验结果表明,测定易挥发元素时石墨平台法能够有效地消除干扰影响。     

人体脏器中钼的石墨炉原子吸收测定方法的研究

本文讨论了用衬钽石管测定人体脏器中钼的方法。初钽管完全消除了形成稳定碳化物的影响,灵敏度较用普通石墨炉管提高约８４倍,较用热解石墨管提高了一个数量级,完全消除 记忆效应,减少了钠、钾、铁等共存元素的干扰．方法简单、准确、快速。     

膨胀石墨与箔条的3毫米波RCS特性对比

基于有限长度、有限电导率圆柱状导体的电磁散射,利用矩量法建立膨胀石墨RCS的计算公式,计算膨胀石墨及石墨干扰弹的平均RCS并测试石墨干扰弹及箔条弹的RCS.结果表明:膨胀石墨对3毫米波具备一定的散射能力,半径为0.12 mm、长度为1.5 mm的单个膨胀石墨粒子平均RCS为0.8676 mm².在干扰材料质量相同的情况下,箔条的RCS是膨胀石墨的7.4倍,膨胀石墨难以对制导武器实施箔条式的诱饵欺骗干扰.     

Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide

Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.     

Femtosecond Transform-Limited Pulse Generation by Compensating for the Linear Chirp of SPM Spectra in Dispersion Shifted Fibers

A simple technique of pulse compression, based on the linear chirp compensation of self-phase modulation (SPM) spectra in dispersion shifted fibers, is demonstrated. The optimization procedure is carried out, for a short span of a single-mode fiber, using a parabolic law, which describes the behavior of the squared output pulse width versus the pump peak power in the case of Gaussian pulses. The experimental results give a minimum pulse duration of 233 fs, which is in good agreement with the model. Shorter and coherent pulses, down to 90 fs, have been obtained by inserting an interference filter at the optical output.     

Effect ofγ-radiation on the spectral luminescence characteristics of impure cadmium tungstate crystals

Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation (5.5·10⁴ Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure crystals is analyzed (preliminarily). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997.     

Sorting of bending magnets for the SSRF booster

The Shanghai Synchrotron Radiation Facility(SSRF)booster ring,a full energy injector for the storage ring,is deigned to accelerate the electron beam energy from 150MeV to 3.5GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping.Closed orbit distortion(COD)caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting.Considering the affections of random errors in measurement,both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5is given as the final installation sequence of the booster bending magnets in this paper.     

Measurement of nonlinear coefficient of optical fiber based on small chirped soliton transmission

We measure the waveform and phase curves of short optical pulses before and after transmission over different lengths of fibers by use of the pulse analyzer with the frequency-resolved optical gating (FROG),and numerically simulate pulse evolution under the experimental conditions.The nonlinear coefficient of the fiber is given by comparing the experimental results with the numerical ones.Difference between the experiment and numerical simulation is analyzed.     

Resonance scattering of canonical elastic shells in absorbing fluid medium

Resonance scattering of elastic spherical shell and cylindrical shell while the surrounding fluid medium has absorption is studied. The normal mode solution derived using exact elastic theory and the separation of variables is still applicable. However, the scattering form function has to be modified for the absorbing medium, otherwise the unreasonable result would be obtained. The backscattering form function in the absorbing medium is redefined, and the form function of elastic spherical and cylindrical shell with vacuum or solid matter filled is calculated in various absorption conditions. The results show that the absorption of surrounding fluid leads to notable attenuation of the coincidence resonances in the mid-frequency, but it has a little influence on the low-frequency resonance scattering induced by the filler inside the shell.     

Single-beam self-referenced phase-sensitive surface plasmon resonance sensor with high detection resolution

A versatile and low-cost single-beam self-referenced phase-sensitive surface plasmon resonance(SPR)sensing system with ultra-high resolution performance is presented.The system exhibits a root-mean-square phase fluctuation of ±0.0028.over a period of 45 min.i.e.a resolution of±5.2×10-9 refractive index units.The enhanced performance has been achieved through the incorporation of three design elements:a true single-beam configuration enabling complete self-referencing so that only the phase change associated with SPR gets detected,a differential measurement scheme to eliminate spurious signals not related to the sensor response,and the elimination of retardation drifts by incorporating temperature stabilization in the liquid crystal phase modulato .Our design should bring the detection sensitivity of non-labeling SPR biosensing closer to that achievable by conventional fluorescence-based techniques.     

Influences of SiO2 protective layers and annealing on the laser-induced damage threshold of Ta2O5 films

Ta2O5 films are prepared on BK7 substrates with conventional electron beam evaporation deposition.The effects of SiO2 protective layers and annealing on the laser-induced damage threshold (LIDT) of the films are investigated.The results show that SiO2 protective layers exert little influence on the electric field intensity(EFI)distribution,microstructure and microdefect density but increase the absorption slightly.Annealing iS effective on decreasing the microdefect density and the absorption of the films.Both SiO2 protective layers and annealing are beneficial to the damage resistance of the films and the latter is more effective to improve the LIDT.Moreover,the maximal LIDT of Ta2O5 films is achieved by the combination of SiO2 protective layers and annealing.     

A stereo matching algorithm using multi-peak candidate matches and geometric constraints

Gray cross correlation matching technique is adopted to extract candidate matches with gray cross correla- tion coefficients less than some certain range of maximal correlation coefficient called multi-peak candidate matches. Multi-peak candidates are extracted corresponding to three closest feature points at first. The corresponding multi-peak candidate matches are used to construct the model polygon. Correspondence is determined based on the local geometric relations between the three feature points and the multi-peak candidates. The disparity test and the global consistency checkout are applied to eliminate the remaining ambiguous matches that are not removed by the local geometric relational test. Experimental results show that the proposed algorithm is feasible and accurate.