原子荧光光谱法同时测定水中痕量砷和硒

用浓盐酸和5%硫脲-5%抗坏血酸混合试剂处理样品,并以2%硼氢化钾和0.5%氢氧化钾为还原剂,在5%的盐酸介质中用原子荧光光谱法同时测定水中砷和硒.对原子化器的高度、灯电流、负高压等实验条件进行了优化选择,确立了最佳分析条件.砷和硒的检出限分别为As:0.5μg/L,Se:0.1μg/L.     

石墨炉原子吸收光谱法测定水中的铝

采用石墨炉原子吸收光谱法,加入基体改进剂,测定水中痕量铝.铝在1.6-8.0μg/L范围内具有良好的线性关系.重点讨论了铝的灰化温度、原子化温度以及基体改进剂的选用对铝测定结果的影响,结果表明,相对标准偏差为2.1%-3.2%,回收率为98.56%-99.08%,具有良好的精密度和回收率.方法简便快速、结果准确.     

泡塑富集-石墨炉原子吸收光谱法测定地质样品中微量铊

采用HF-HClO4-HNO3溶解样品,泡沫塑料富集-石墨炉原子吸收光谱法测定岩石、土壤、水系沉积物等地质样品中微量铊。以抗坏血酸为基体改进剂,Fe3+加入量选择200mg,灰化温度为600℃,原子化温度为1600℃。方法用于测定国家一级标准物质,结果与标准值基本一致。方法精密度(RSD,n=8)为2.73%—3.93%,回收率为96.7%—101.3%,检出限可达0.060μg/g。     

涂钼热解石墨管电热原子吸收测定痕量镓的研究

比较了不同基体改进剂 ,不同涂层对镓在热解石墨管中原子化的影响。研究了以硝酸镍为基体改进剂 ,以涂钼热解石墨管为原子化器镓的原子化机理 ,优化了各项参数 ,找到了一种测定复杂样品中痕量镓的新方法。方法特征量为 2 1 2× 1 0 -1 1 g ,检出限为 1 4× 1 0 -1 0 g ,RSD≤ 3 6 % (n =1 1 ) ,样品回收率 97 4 %～1 0 2 7%。     

氢化物发生-原子荧光光谱法测定螺旋藻中的铅

研究了氢化物发生-原子荧光光谱法测定螺旋藻中Pb的适宜条件,分析了酸度、硼氢化钾和基体改进剂浓度、载气流量、灯电流以及原子化器高度等对测定的影响,优选了测定条件.结果表明,铅发生氢化物反应条件为酸性介质,1.5％的盐酸作载流,硼氢化钾还原剂浓度为20g/L,载气流量为500mL/min,空心阴极灯灯电流为60mA,原子化器高度为10mm,此时荧光值强度较大且稳定.最佳测定条件下,其线性范围为0-100ng/mL,相关系数0.9994,仪器检出限为0.383μg/L,相对标准偏差为1.39％,回收率为88.9％-95.9％.用标准物质进行对照,其测定值在给定的标准值不确定度范围之内.对螺旋藻中铅的测定,结果令人满意.     

悬浮体进样-基体改进效应石墨炉原子吸收光谱法直接测定土壤中的铅和镉

建立了以悬浮体进样-基体改进效应石墨炉原子吸收法测定污灌区土壤中痕量铅和镉的新方法。以琼脂为悬浮剂、NH₄H₂PO₄作基体改进剂,研究了土壤悬浮液的稳定性和基体改进效应及干扰效应。基于原子化峰值时间的对数值与原子化温度之间的线性关系测得Cd和Pb的表观活化能,探讨了基体改进效应机理。应用标准曲线进行校准, Pb和Cd的检出限分别为9.05×10-10 g·mL-1和1.76×10-11 g·mL-1,Pb和Cd的回收率分别为91%～97%和93%～109%,相对标准偏差为4.2%～7.8%。以土壤标准品作参照, 测得值与标准值相符。     

基体溶液改进-原子荧光法测定食品中的汞

探讨改进基体溶液双道原子荧光光谱法测定食品样品中的汞。样品消解后用6mol/L盐酸、硫脲+抗坏血酸(50g/L)作为基体溶液进行仪器测定。本方法检出限0.051μg/g,最低检出质量浓度0.10μg/L,相对标准偏差为7.45%、6.76%,回收率为88.6%—113.2%。方法具稳定性好、灵敏度高、检出限低等优点。     

微波消解-氢化物发生原子荧光法测定重油中的砷和汞

采用微波消解处理样品,以硫脲为预还原剂硼氢化钾为还原剂,氢化物发生原子荧光法测定重油中的砷和汞。采用微波消解方法进行样品处理,其结果表明,方法具有高效快速、试剂消耗量少、节能、环保等优点。考察了预还原剂硫脲和抗坏血酸对测定结果的影响。考察了酸度、还原剂浓度、基体效应、光电倍增管负高压、原子化器高度、灯电流和载气流量的影响,优化操作条件。测定砷和汞的线性范围分别为2~12μg/L和0.2~1.2μg/L,线性回归方程为If=a*c+b(c:μg/L),相关系数分别为0.9998和0.9981,砷和汞的检出限分别为0.009μg/L和0.007μg/L,对7个样品进行回收实验,砷、汞的回收率分别为90%~109%、92%~105%准确度较高;11次测定的标准偏差小于5%,精密度较好。本方法用于重油中砷和汞分析,可满足科研和生产需要。     

平台石墨炉原子吸收法测定合金钢中痕量镉

本文研究了平台石墨炉原子吸收法直接测定合金钢中的痕量镉,不需分离,不需加基体改进剂。测定范围为Cd 1μg/g～10μg/g;相对标准偏差为9.0%～14.0%;回收率为98%～102%。     

石墨炉原子吸收光谱法测定纯金中痕量铋

以乙酸乙酯萃取样品中基体金,将萃取样品后的含金的乙酸乙酯作为基体改进剂加入到铋标准溶液中,使得标准与样品的基体组成匹配,用石墨炉原子吸收法测定水相样品中的铋.并对石墨炉加热程序中的干燥时间、灰化温度及原子化温度进行了考察,探讨基体改进剂、介质酸度、萃取效率及共存的离子对测定的影响.方法特征量为8.3pg,检出限为2.26μg/L,相对标准偏差为1.89%-3.69%,回收率在93%-106%之间.该方法的精密度高,回收率好,且具有快速、简便的特点.     

Theoretical analysis and simulation of conjugate heights for dual-conjugate AO system in lidar

A multi-conjugate adaptive optics （MCAO） can offer a possibility of widening field of view （FOV） characterized by the isoplanatic angle, and the choose of conjugate height becomes a basic problem for MCAO, which influences the size of iosplanatic angle. Considering the application of lidar, the isoplanatic angle＇s expressions of two deformable mirrors （DMs） MCAO for uplink and downlink are deduced. The effects of conjugate heights for dual-conjugate AO are thoughtfully discussed, and the isoplanatic angles are further analyzed. The results show that the isopanatic angle varies with the conjugate height and reaches the maximum as the conjugate height is at the optimal altitude. Moreover, the optimal conjugate height changes with the propagation distance.     

Quick single-photon detector with many avalanche photo diodes working on the time division

Due to the limit of response speed of the present single-photon detector, the code rate is still too low to come into practical use for the present quantum key distribution (QKD) system.A new idea is put up to design a quick single-photon detector.This quick single-photon detector is composed of a multi-port optic-fiber splitter and many avalanche photo diodes (APDs).Au of the ports with APDs work on the time division and cooperate with a logic discriminating and deciding unit driven by the clock signal.The operation frequency lies on the number N of ports, and can reach N times of the conventional single-photon detector.The single-photon prompt detection can come true for high repetition-rate pulses.The applying of this detector will largely raise the code rate of the QKD, and boost the commercial use.     

Characterization of PolyA and PolyC mismatches by Raman spectroscopy

A.C mismatches are studied by Raman spectral characterization of PolyA, PolyC, and their equimolar complex in solution of 0.14 mol/L Na ,pH7.0.Experimental results show that A·C mismatches occur to be A/B (mainly A) conformers, and unlike Watson-Crick base pairing, this kind of mismatches is stabilized by only one hydrogen bond involving cytosine N4H2 and adenine N7.The formation of A·C complex makes the base stacking interactions much stronger, and conformation of the backbone more ordered, which leads to obvious Raman hypochromic effect with some shifts in corresponding bands.     

Improvement of four-wave mixing-based wavelength conversion efficiency in dispersion shifted fiber by 40-GHz clock pumping

40-GHz clock modulated signal as a pump to improve the efficiency of four-wave mixing (FWM)-based wavelength conversion in a 26.5-km dispersion shifted fiber (DSF) is investigated. The experimental results demonstrate that the conjugated FWM component has higher intensity with the clock pumping than that with the continuous-wave (CW) light pumping. The improvement of FWM-based wavelength conversion efficiency is negligible when the pump power is less than Brillouin threshold. But when the pump power is greater than Brillouin threshold, the improvement becomes significant and increases with the increment of pump power. The improvement can increase up to 9 dB if pump power reaches 17 dBm.     

Multi-pulse operation of a Kerr-lens mode-locked femtosecond laser

Our experimental results show that the presence of a proper amount of negative group velocity dispersion is essential to multi-pulse operation of a Kerr-lens mode-locked femtosecond laser. We demonstrate that the pulse separations and the number of pulses contained within a cavity round trip are strongly dependent on the initial perturbations. The results allow us to get a better understanding on the influences of the convoluted self-phase modulation and intra-cavity dispersions on the stable multi-pulse oscillation in a Kerr-lens mode-locked femtosecond laser.     

Propagation of Helmholtz-Gauss beams in weak turbulent atmosphere

Based on the Rytov approximation of light propagation in weak turbulent atmosphere,the closed-form expressions of field and average irradiance of each one of the four fundamental families of Helmholtz-Gauss (HzG)beams:cosine-Gauss beams,stationary Mathieu-Gauss beams,stationary parabolic-Gauss beams,and Bessel-Gauss beams,which are propagating in weak turbulent atmosphere,are obtained.The results show that the field and average irradiance can be written as the product of four factors:complex amplitude depending on the z-coordinate only,a Ganssian beam.a factor of complex phase perturbation induced by atmospheric turbulence,and a complex scaled version of the transverse shape of the non-diffracting beam.The effect of weak atmospheric turbulence on irradiance distribution of the HzG beam can be ignored.     

An effective method for reducing speckle noise in digital holography

An effective method for reducing the speckle noise in digital holography is proposed in this paper.Different from the methods based on classical filtering technique,it utilizes the multiple holograms which are generated by rotating the illuminating light continuously.The intensity images reconstructed by a series of holograms generated by rotating the illuminating light possess different speckle patterns.Hence by properly averaging the reconstructed intensity fields,the speckle noises can be reduced greatly.Experimental results show that the proposed method is simple and effective to reduce speckle noise in digital holography.     

Influence of purity of HfO2 on reflectance of ultraviolet multilayer

The impurities in two kinds of HfO2 materials and in their corresponding single layer thin films were determined through glow discharge mass spectrum technology and secondary ion mass spectrometry(SIMS) equipment respectively.It was found that ZrO2 was the main impurity in the two kinds of HfO2 either in the original HfO2 materials or in the electron beam deposited films.In addition,the difference of Zr content in the two kinds of HfO2 single laver films was much laxger than that of the other impurities such as Ti and Fe.which showed that it was just ZrO2 that made the difference between the optical performance of the film products including the two kinds of HfO2.With these two kinds of HfO2 and the same kind of SiO2.we deposited HfO2/SiO2 multilayer reflective coatings at the wavelength of 266 nm.Experimental results showed that the reflectances of these two mirrors were about 99.85% and 99.15% respectively,which agreed well with the designed results what were based on the optical constants obtained from the corresponding single layer thin films.     

Speech enhancement by array crosstalk resistant ANC and spectrum subtraction

Microphone array-based speech enhancement has great importance for speech communications and speech recognition. To reduce the aperture of the microphone array and to increase the effect of the speech enhancement will greatly broaden the application areas of the microphone array. An array crosstalk resistant adaptive noise cancellation method is therefore presented. And then an improved spectral subtraction algorithm is further cascaded to obtain better enhancement results. Theoretic analysis and experiments indicate that the proposed scheme needs only a very small microphone array while it simultaneously achieves a higher SNR improvement. Besides, the proposed scheme can be used in many noisy environments and is easy for real-time implementation.