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.     

碘化钾-甲基异丁基甲酮萃取石墨炉原子吸收光谱法测定蔬菜中痕量镉

采用碘化钾-甲基异丁基甲酮(KI-MIBK)萃取,以2%磷酸二氢铵为基体改进剂,石墨炉原子吸收光谱法测蔬菜中的痕量镉,该方法灵敏度高,加标回收率为94%-105%,标准偏差为4.5%,测定结果稳定可靠,结果令人满意.     

石墨炉原子吸收光谱法测定奶牛血清中硒

本文采用石墨炉原子吸收技术加入基体改进剂直接测定奶牛血清中的痕量元素硒。实验发现使用0.1%Ni(NO3)2作为基体改进剂，可使样品灰化温度提高到1000℃，实际使用灰化温度为600℃经氕灯校正背景，直接测定奶牛血清中的硒含量方法简便省时，回收率在104%-93.3%之间，相对标准偏差为4.9%。     

石墨炉原子吸收光谱法测定湖光岩岩石中的铅

采用3种方法对试样进行消解.使用NaH<,2>PO4为基体改进剂,用石墨炉原子吸收光谱法测定湖光岩岩石中的铅.对试样灰化、原子化温度进行了优化选择.结果表明,样品溶液吸光度与浓度之间存在线性关系,其相关系数为0.9945,精密度小于6.00%,加样回收率在86.97%-101.92%之间.方法简便、快速、准确,满足分析...     

石墨炉原子吸收光谱法测定面制食品中铝

利用混合酸对样品进行消解处理,硝酸镁作为基体改进剂,石墨炉原子吸收光谱法测定面制食品中铝.探讨了相关实验条件,检出限为4.8μg/L,相对标准偏差(RSD)在0.136%-0.188%之间,回收率在88.8%-105.5%之间.本法为一种理想的面制食品中铝的测定方法.     

原子吸收法直接测定食用L-赖氨酸盐酸盐中的铜和铅

本文报道了用石墨炉-原子吸收分析法，将食用L-赖氨酸盐样品经稀酸溶解后，直接进样测定。该方法省去了通常必需的干灰化或湿消解过程，充分利用石墨炉本身所具的对样品进行部分预处理的功能，在无基体改进剂的条件下，快速测定样品中的Cu和Pb的含量。方法简便，快速，准确，实用，Cu和Pb的精密度试验的相对标准偏差分别为4.8%和5.3%；回收率分别为100%-110%和102%-105%。     

微波消解石墨炉原子吸收光谱法测定蒙山全蝎中的痕量锗

建立了石墨炉原子吸收光谱法测定蒙山全蝎中痕量元素锗的方法.通过程序控温、控压的分步微波消解方式消解样品,优化石墨炉升温程序,采用Ni(NO3)2为基体改进剂,以氘灯扣除背景,在265.2nm波长下测定蒙山全蝎中痕量元素锗.在选定分析条件下,锗的检出限为0.30μg/L,RSD的范围为1.2%-3.1%,回收率为88.9...     

塞曼石墨炉原子吸收光谱法测定海水中的铬

利用石墨炉原子吸收光谱法测定海水中铬,塞曼效应扣除背景,选择抗坏血酸为基体改进剂.线性范围5-15μg/L,相关系数为0.9999,回收率为90%-102%,相对标准偏差为7.0%.     

石墨炉原子吸收光谱法测定植物提取物中微量镉

采用磷酸二氢铵作为基体改进剂,石墨炉原子吸收光谱法测定植物提取物中的微量镉.条件优化后的方法简便、快速、重现性好、灵敏度,准确度高.添加浓度为0.010-0.100mg/kg时,回收率为87.7%-103.9%.方法检出限0.08ng/mL.     

石墨炉原子吸收光谱法直接测定城市污泥中有机态镉

建立了真空冷冻干燥法制备有机相标准系列,氯化钯-磷酸氢二钾作基体改进剂,分步斜坡升温石墨炉原子吸收光谱法直接测定城市污泥中痕量有机态Cd的方法,有效地消除了基体干扰.方法的精密度(RSD,n=11)为5.7%,用于污泥样品的测定加标回收率在91%-107%之间,与常规消解法测定值比较结果令人满意.     

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.