一套红外池测定精四氯化钛中二氯氧钛的含量

钛材质量控制的关键是控制精TiCl₄中杂质含量。精TiCl₄是海绵钛生产的关键环节,海绵钛中杂质与精TiCl₄中杂质含量成4倍富集关系。需要分析氧杂质的来源,对精TiCl₄中氧杂质进行严格控制。精TiCl₄中TiOCl₂含量的测定具有重要意义。TiOCl₂具有红外吸收谱线,因而能够利用红外光谱实现测定,然而精TiCl₄与空气中水气接触极易发生水解反应,生成强腐蚀性的盐酸烟雾,不能使用常规的红外吸收池进行测定。根据Lambert-Beer定律,被测组分浓度(c_x)与吸光度(A)～样品光程(L)曲线的斜率成正比,利用波长范围7 800～440 cm-1的硒化锌窗片(10×1 mm)和玻璃池体(22,12,7和4 mm光程)组装成一套红外吸收池,采用加标法测定精TiCl₄中TiOCl₂杂质含量。实验得出TiOCl₂的检出限为17.8 mg·kg-1,样品回归方程Y=1.0118X,相关系数r为0.996 3,加标TiOCl₂样品的回归方程Y=1.940 0X,相关系数r为0.997 0,线性关系较好。测定精TiCl₄中TiOCl₂含量为833.8 mg·kg-1,标准偏差(SD)为40.0 mg·kg-1,方法精密度相对标准偏差(RSD)在0.95～1.94之间,加标回收率在88.5%～93.1%之间。此红外吸收池安全简便、容易拆洗、可重复使用,通过一次加标样品定量分析精TiCl₄中TiOCl₂含量,可满足精TiCl₄中TiOCl₂分析的要求。     

利用多光程光谱法检测血液多种成分含量的研究

为研究利用血清多光程光谱信息检测血液成分含量的可行性,通过设计自动微位移测量装置实现了对200份血清样品0～4.0 mm(间隔0.2 mm)近红外多光程光谱的测量。利用多光程光谱的非线性特性,使用血清多光程光谱共同参与建模的方法,对血清样品的葡萄糖(GLU)、总胆固醇(TC)、总蛋白(TP)和白蛋白(ALB)四种成分含量进行定量分析。采用偏最小二乘法(PLS)对160个血清样本的多光程近红外吸收谱与全自动生化分析仪得到的生化分析结果建立校正模型,并对预测集40个样本进行预测。４种血液成分预测值与生化分析结果的相关系数(r)分别为0.932 0,0.971 2,0.946 2和0.948 3。研究结果证明多光程光谱法建模方法用于血液成分含量分析的可行性,为利用多光程光谱法实现方便、快捷的检测血液以及其他液体成分含量奠定了基础。     

反相高效液相色谱法测定盾叶薯蓣中薯蓣皂甙元

建立反相高效液相色谱法测定新鲜盾叶薯蓣中薯蓣皂甙元的含量,采用VP-ODS(150×4.6mm,5μm)色谱柱,甲醇:水=95:5(V/V)流动相,1.0mL·min-1流速,208nm的UV检测波长对薯蓣皂甙元含量进行测定,结果表明薯蓣皂甙元在0.1-2.0g·L-1范围内峰面积与其质量浓度具有很好的线性关系(r=0.9998),样品平均加标回收率为99.76%,精密度RSD为2.19%.该法测定样品准确,重复性好,能快速检测盾叶薯蓣中薯蓣皂甙元的含量.     

基于TG-FTIR的生物质内在金属盐催化热解研究

采用热重和傅里叶红外光谱联用(TG-FTIR)对去离子水、盐酸淋洗后的稻草样品和原样进行分析,探讨生物质内在金属盐对热解过程和产气组分的催化作用规律。结果表明:碱金属对稻草样品热解具有重要的催化作用,相反Ca等碱土金属抑制了纤维素的分解。红外检测的三种样品热解气体产物主要为CO_2、CO、CH_4、H_2O和一些含C-O-C和C=O半挥发性有机物。经过水洗后CO_2、CO产量减少,CH_4和半挥发性有机物产量增加;而酸洗样品气体产量都明显低于其它两种样品。这些与稻草内在碱金属和碱土金属盐的不同催化作用有关。     

Mn(Ⅱ)-5-Br-PADAP共沉淀-火焰原子吸收光谱法测定虾、贝样中的镉

提出了一种测量痕量重金属镉的新方法。该方法创新性地以Mn(Ⅱ)作为载体离子,以2-(5-溴-2-吡啶偶氮)-5-二乙氨基苯酚(5-Br-PADAP)作为共沉淀剂,共沉淀分离富集虾、贝样品中的镉,同时采用火焰原子吸收法进行测定。重点探讨了共沉淀剂加入量、载体离子加入量、pH值、共沉淀时间、共存离子的干扰等因素对共沉淀分离富集效果的影响, 从而确定了Mn(Ⅱ)-5-Br-PADAP共沉淀分离富集测定镉的最佳共沉淀条件。实验结果表明,当pH 7且大量干扰离子存在的条件下,Mn(Ⅱ)-5-Br-PADAP体系对镉有良好的共沉淀分离富集效果,很好地克服了基体干扰。共沉淀体系中镉含量在0.1～1.0 mg·L-1范围内时镉含量与吸光度呈线性关系。该方法的灵敏度为0.147(mg·L-1)-1,精密度为0.73%,对镉的检出限(3σ)为4.27 μg ·L-1。食品样品比较复杂,对其中痕量重金属含量的测定必须经过消化、分离富集等一系列预处理过程才能得到最准确地答案。所以通过对比直接用火焰原子吸收法与应用本方法测定样品中镉含量的区别,进一步说明了Mn(Ⅱ)-5-Br-PADAP体系对样品中重金属镉有很好的分离富集效果。根据该方法,采用标准加入法测得干贝样品中镉的含量为1.85 mg·kg-1,干虾样品中镉的含量为1.74 mg·kg-1,基本符合国际食品法典委员会的标准。为了证明该方法的可靠性与真实性,做了加标回收实验,结果显示干虾干贝样品中镉的加标回收率范围为99.9%～100.3%,相对标准偏差为0.15%～0.83%。用Mn(Ⅱ)-5-Br-PADAP共沉淀分离富集样品中的痕量镉具有重现性好、准确度高、简单快速等的优点,分析结果令人满意。     

腔衰荡光谱方法测量大气中痕量NH_3的浓度

NH_3是大气二次细颗粒物的主要前驱物之一,NH_3浓度的准确测量对于大气环境监测和保护具有重要意义。近红外波段激光器的成本较低,但采用其测量NH_3时,普遍存在受环境中H_2O、CO_2气体干扰以及吸收光程较短等问题。为克服环境中H_2O、CO_2干扰气体的影响,筛选出中心波数为6521.97 cm~(-1)的吸收谱线,利用该谱线对大气环境中痕量NH_3的浓度进行测量。该谱线不受环境中CO_2吸收的影响,且在低压条件下与H_2O吸收谱线的重叠范围较小,通过多峰拟合可以准确提取出NH_3的光谱吸收率。基于分布反馈式激光器搭建了一套腔衰荡吸收光谱测量装置,在该装置中,衰荡光腔由一对反射率高达99.996%的高反镜构成,空腔衰荡时间约96μs,有效吸收光程可达1.6×10~4 m。利用该装置对大气环境中痕量NH_3的浓度进行测量,结果表明:该测量系统的探测灵敏度可以达到3.9×10~(-10)。     

聚对苯二甲酸乙二醇酯C=O伸缩振动模式ATR二维相关红外光谱研究

采用变温傅里叶变换衰减全反射红外光谱技术(ATR-FTIR)结合二维相关红外光谱技术,分别研究了聚对苯二甲酸乙二醇酯(PET)的羰基红外伸缩振动模式(νC=O)。研究发现:玻璃转化温度(Tg)以下时,PET的νC=O的红外吸收频率包括1700cm~(-1)、1709cm~(-1)和1718cm~(-1),而随着测定温度的升高(313~343K),其红外吸收强度变化快慢顺序为:1709cm~(-1)1700cm~(-1)1718cm~(-1);而当在Tg以上时,PET的νC=O的红外吸收频率包括1709cm~(-1)和1718cm~(-1),而随着测定温度的升高(353~393K),PET的νC=O红外吸收强度变化快慢顺序为:1718cm~(-1)1709cm~(-1)。本项研究拓展了ATR二维相关红外光谱技术在PET高分子材料热变性研究的范围。     

离子色谱-电感耦合等离子体质谱联用测定中成药,水体及饮料中痕量BrO_3~-及Br~-

建立了离子色谱-电感耦合等离子体质谱联用技术(IC-ICP-MS)测定溶液中溴酸根离子(BrO3-)和溴离子(Br-)的方法。使用Hamilton PRP X-100(150×4.1mm,10μm)阴离子交换柱,On-guardⅡRP(4×50mm)保护柱,采用10mmol·L-1 NH4NO3作为淋洗液,在流速2mL·min-1下分离BrO3-和Br-。其中BrO3-在标准溶液浓度4.8～160.0ng·L-1范围内线性良好,y=250.31x-45.43,R2=0.9999;Br-在标准溶液浓度4.2～140.0ng·L-1范围内线性良好,y=186.84x-127.10,R2=0.9994。加标回收率分别为98.9%～109.5%和97.4%～106.1%。测定样品包括中成药、瓶装饮用水、自来水、河水、酒类、果汁和碳酸饮料等。其中14种瓶装饮用水和2种自来水中检出BrO3-,其余样品均未检出BrO3-。而Br-则普遍存在于各种样品中。     

氢化物原子荧光光谱法测定涂料中可溶性汞

用酸泡法(GB 18582-2001)处理粉碎的涂料干膜样品,氢化物原子荧光光谱法测定样品中可溶性汞含量,选择最佳实验条件,荧光强度与汞浓度在0-10ng·mL-1范围内呈线性关系,检出限为0.0015ng·mL-1,加标回收率为90.0%-103.3%,进行了大量样品测定,结果满意.     

火焰原子吸收光谱法测定栽培甘草中6种金属元素

浓硝酸 -高氯酸 (V∶V=4∶ 1 )常压微沸条件下消解甘草样品 ,火焰原子吸收法 (FAAS)测定甘草中的金属元素 Ca、Mg、Fe、Cu、Zn、Pb的含量 ,研究了测定不同元素的仪器最佳工作条件及溶液介质对测定结果的影响及方法的准确性和精密度研究。栽培甘草中 Ca、Mg、Fe、Cu、Zn的含量分别为 4 0 4 5 .5、71 5 .4、2 79.8、1 2 .6、1 0 .4 μg/g,Pb未检出。方法的加标回收率为 99.38%— 1 0 2 .30 %,相对标准偏差 (n=9)为0 .4 1 %— 1 .6 8%。本法简单易行 ,方便快捷 ,结果可靠。     

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.