钇基体改进剂石墨炉原子吸收法测定微量锗

本文利用硝酸钇做基体改进剂，石墨炉子原子吸收法测定植物样品及土壤样品中的微量锗，本方法采用涂钼热解石墨管，有效地避免了测定过程中锗的损失，方法的检出限为５．９×１０＾－１２ｇ，对于３０μｇ／Ｌ，锗的相对标准偏差为４．０％。     

石墨炉原子吸收法测定饮料和中成药中锗

本文研究了石墨炉原子吸收（ＧＦＡＡＳ）直接测定某些饮料和中成药中的锗。选用钯和酒石酸为改进剂与纯钯比较，灰化温度提高至１６００℃未见锗的损失，灵敏度提高了３７％。具有较强的抗干扰的能力。本法特征质量ｍｏ值为３２ｐｇ，实际样品测定检出限为０．２４μｇ／Ｌ（３σ计），相对标准偏差为２．６％，回收率８９％－１１０％。     

泡沫塑料吸附—石墨炉原子吸收光谱法测定地质物料中痕量铊

本文研制定了一种泡沫塑料吸附－石墨炉原子吸收光谱法测定地质物料中痕量铊的分析，在所先定的实验条件下，方法检出限为０．０５μｇ／ｇ、样准曲线范围为１０－３００ｎｇ／ｍＬ，Ｔｌ含量水平为０．７１μｇ／ｇ时的测定精度为６．０％，方法回收率９９．０％－１００．０％。经标样及大量样品分析验证，分析方法准确可靠。     

火焰原子吸收光谱测定微量锗的研究

本文研究了空气－乙炔火焰原子吸收分光光度法测定饮料及灵芝酒中微量金属元素锗。该法线性范围宽（５０－３００μｇ／ｍｌ），选择性强，并有良好的精密度和准确度。样品加标回收率为９７．９－１０３．４％，变异系数１．４％。本方法适用于保健滋补饮品中锗的分析。     

草酸铵作稳定剂石墨原子吸收法直接测量土壤悬浮液中微量镉

本研究了石墨炉原子吸收法直接测量土壤浮液中微量镉。比较子不同基体改进剂及背景吸收对测量的影响。并以草酸铵为稳定剂对悬液的稳定性进行了研究，结果表明在碱性条件下，使用０．００７ｍｏｌ·Ｌ＾－１的草酸铵作稳定剂时，土壤悬浮液比较稳定。应用固体悬浮液进样方法，直接测定了土壤样品中的微量镉。     

流动注射在线萃取－火焰原子吸收光谱法测定明胶中的微量Fe和Cu

本文采用氧化水解制样及流动注射在线萃取火焰原子吸收光谱法，测定明胶中微量Ｆｅ和Ｃｕ，解决了水解法制样测定结果偏低和不能直接测定低含量样品的问题。本方法测定Ｆｅ和Ｃｕ的灵敏度分别提高了１４．５倍和１７．６倍，分析速度达３６次／ｈ，Ｆｅ和Ｃｕ的回收率分别在９０．８－１１０．５％和８７．５～１０７．０％之间，测定精密度分别为４．５３％和４．２６％。     

固体进样石墨炉原子吸收光谱测定研究（Ⅱ）：镉的测定

采用自制的石墨炉微量固体进样装置，结合Ｌ＇ｖｏｖ平台、基体改进以及预热时通入空气等技术，直接测定了部分植物、粮食、土壤与沉积物中的痕量镉。初步解决了上述试样测定中的基体干扰、背景扣除疑难问题。标样测定取得了满意的结果。变异系数６．２～１１．０％；回收率９３～１０５％。     

萘相萃取双波长分光光度法测定微量铜的研究

本文用蔡作萃取剂，以５－Ｂｒ－ＰＡＤＡＰ为显色剂，采用双波长分光光度法测定微量铜的研究。研究表明，选择５４０－３８３ｎｍ，为测定波长时，络合物最大吸收峰为５４０ｎｍ，表观摩尔吸光系数为１．２６×１０＾５Ｌ．ｍｏｌ＾－１．ｃｍ＾－１，铜量在０－５．０μｇ／７ｍＬ范围内符合比耳定律，方法应用于食品，水样品铜的测定，结果满意。     

草酸铵作稳定剂石墨炉原子吸收法直接测量土壤悬浮液中微量镉

本文研究了石墨炉原子吸收法直接测量土壤悬浮液中微量镉。比较了不同基体改进剂及背景吸收对测量的影响。并以草酸铵为稳定剂对悬浮液的稳定性进行了研究,结果表明在碱性条件下,使用０．００７ ｍ ｏｌ·Ｌ－ １ 的草酸铵作稳定剂时, 土壤悬浮液比较稳定。应用固体悬浮液进样方法, 直接测定了土壤样品中的微量镉     

等离子体发射光谱法测定单晶硅中微量锗

本文阐述了用等离子体发射光谱法测定单晶硅中微量锗的方法。试验了三种样品制备方法，结果表明，样品溶解于硝酸加氢氟酸中，除云硅后直接测定锗的方法最好，其检出限是0.0237μg/mL，合成样品的回收率为99.9%－100.2%，相对标准偏差小于3.6%。     

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.