高质量AIP04-5分子筛大单晶的合成与表征

以拟薄水铝石作为铝源，正磷酸为磷源，正三丙胺(TPA)作模板剂，采用水热法合成了AIPO4-5分子筛．在不同的反应物配比、温度以及晶化时间条件下，得到了不同尺寸的AIPO4-5分子筛单晶．实验表明，反应物质的摩尔比为Al2O3：P2O5：TPA：C2H5OH：H2O：HF=1：1．2：2．66：80：1000：0．7，反应温度为457K，晶化时间48h是生成六方AIPO4-5分子筛大单晶较适宜的条件；在该反应条件下合成出纵向尺度最大达到2．0mm、具有完整六方棱柱形态的MPO4-5分子筛单晶；部分晶体的横向尺度达到0．31mm．用扫描电镜观察晶体的形貌：AlPO4-5分子筛晶体结构通过SMART1000单晶衍射仪鉴定．     

K2O·CaO·4B2O3·12H2O∶Nd3+的合成及发光性能

以CaCl2、K2B4O7和Nd2O3为原料,采用易于工业化、无污染的水溶液法反应合成碱-碱土金属硼酸盐K2O·CaO·4B2O3·12H2O∶Nd3+晶体,利用X射线衍射、红外光谱、扫描电镜、荧光分光度计等现代分析测试手段,对所合成晶体进行了分析和表征.结果表明,所制备的K2O·CaO·4B2O3·12H2O∶Nd3+晶型发育良好、形貌规整.基质本身具有上转换发光特性,K2O·CaO·4B2O3·12H2O∶Nd3+的发光强度较基质弱.当激发源为828 nm时,材料呈橙红色光.     

制备条件及添加稀土对SO_4~(2-)/ZrO_2-Al_2O_3固体超强酸酸性影响的研究

用共沉淀法制备了SO4 2 -/ZrO2 -Al2 O3 固体超强酸 ,并采用低温陈化和添加稀土La对其制备方法进行改进 .通过样品催化正丁烷异构化反应考察了该固体超强酸中nZr和nAl的最佳配比为 1∶2 .该法制备的样品的IR显示 ,在 1393cm-1处的吸收峰强度较常温陈化样品大大增加 .XRD分析表明 ,低温陈化和加入稀土添加剂的样品在6 5 0℃焙烧温度下 ,出现了亚稳态的ZrO2 四方晶相的晶体是表面酸性和催化活性增加的微观原因 .样品催化合成八乙酸蔗糖酯反应结果同样证明 ,在相同的时间内 ,低温陈化和添加稀土添加剂的样品具有较好的催化活性     

K2O·CaO·4B2O3·12H2O∶Nd3+的合成及发光性能

以CaCl2、K2B4O7和Nd2O3为原料,采用易于工业化、无污染的水溶液法反应合成碱-碱土金属硼酸盐K2O·CaO·4B2O3·12H2O∶Nd3+晶体,利用X射线衍射、红外光谱、扫描电镜、荧光分光度计等现代分析测试手段,对所合成晶体进行了分析和表征.结果表明,所制备的K2O·CaO·4B2O3·12H2O∶Nd3...     

陈化温度和Fe/Zr配比对SO42-/Fe2O3-ZrO2固体超强酸结构与性能的影响

用低温陈化法制备了SO42 -/Fe2 O3 ZrO2 (简称SFZ)固体超强酸催化剂 ,用红外光谱 (IR)和X光衍射(XRD)对其结构进行了表征 ,并考察了它对合成癸二酸二正丁酯的催化性能 .IR谱显示 ,低温陈化的SFZ样品在10 70cm-1处吸收峰远强于常温陈化样品 .XRD分析则显示 ,在焙烧温度为 6 5 0℃、Fe/Zr为 2∶1时 ,低温陈化的样品出现了亚稳态的ZrO2 四方晶相 .该样品在催化酯化反应中使产率达 90 %以上 ,高于常温陈化样品的 30 % .研究结果表明 :在其他条件不变时 ,低温陈化所出现的亚稳态的ZrO2 四方晶相是表面酸性和催化活性增加的微观原因     

六方单晶氮化铝薄膜的合成与紫光发光机理

利用无水三氯化铝与叠氮化钠在无溶剂的条件下直接反应,成功地合成出六方单晶氮化铝(h-AlN)薄膜.反应温度为450℃,有效反应时间为20 h.高分辨率透射电镜发现为薄膜形态；电子衍射和X射线衍射结果都表明,氮化铝薄膜为六方结构.光致发光实验显示,在可见光范围内有一较强的辐射峰,中心位于413 nm处,半高宽约为5 nm.同时,本文对六方单晶氮化铝薄膜的生长机理和光致发光机理也进行了讨论.     

钒(Ⅴ)-5-Br-PADAP-H2O2-吐温-80显色体系的研究与应用

研究了在非离子表面活性剂吐温 - 80存在下 ,钒 ( )与 2 - [(5 -溴 - 2 -吡啶 ) -偶氮 ]- 5 -二乙氨基苯酚 (5 -Br- PADAP)及 H2 O2 的显色反应。实验表明 :在 p H1.5— 4 .0范围内 ,钒 ( )与 5 - Br- PADAP、H2 O2 形成稳定的配合物 ,最大吸收峰位于 5 95 nm处 ,表观摩尔吸光系数为 6 .2× 10 4L· mol-1· cm-1,配合物组成比为钒 ( )∶ 5 - Br- PADAP∶ H2 O2 =1∶ 1∶ 1。钒含量在 0— 15μg/ 2 5 m L范围内服从比耳定律。该方法灵敏度较高 ,用于合成水样中钒的测定 ,结果令人满意。     

一个Schiff碱配体的镍和锌配合物的合成及晶体结构

合成了两个含邻甲氧基苯甲醛Schiff碱配体的单核过渡金属配合物:Ni (C15H13N2O3)2 (1)和Zn (C15H13N 2O3)2(2).采用元素分析和单晶X-射线衍射对制备的晶体进行了结构表征.结构分析表明,这两个配合物属于异质同晶,晶体属四方晶系,空间群为P41212,Z=4.镍原子和锌原子都形成了扭曲的八面体配位构型.配体的酚氧原子(O1和O1A)未与金属原子配位,而甲氧基的氧原子(O3和O3A)却与金属原子配位.     

钬铝石榴石晶场参数调整

利用比热实验值,对钬铝石榴石（Ho3Al5O12）晶体的晶场参数进行了调整,依此计算了Ho3Al5O12晶体的晶场能谱、Zeeman劈裂能级和波函数. 在外磁场H=0时,分别计算了Ho3Al5O12晶体的总比热、总熵随温度的变化,以及外磁场H=10kOe时该晶体倒数磁化率的温度关系,理论计算结果均与已有实验数据符合较好.该工作为进一步探究该晶体的其它性质奠定了必要的理论基础,对实际生产和科学研究中磁制冷材料的优化选取也具有一定的现实意义.     

Lu2Si2O7∶Ce纳米晶的溶胶-凝胶法合成和闪烁性能

采用溶胶-凝胶法制备了Lu2Si2O7∶Ce纳米晶,利用X射线衍射(XRD)、扫描电镜(SEM)、荧光光谱仪、X射线激发发射谱仪对制备的Lu2Si2O7∶Ce纳米晶的晶相结构、微观形貌和光学性能进行了表征。结果表明,溶胶-凝胶法制备的Lu2Si2O7∶Ce前驱体在煅烧温度为1000℃时开始晶化,晶粒尺寸随着煅烧温度的升高而变大,1200℃煅烧2 h后的晶体颗粒均匀,分散性最优,平均晶粒尺寸约为28.9 nm,呈近球形;Lu2Si2O7∶Ce纳米晶的紫外吸收谱存在峰位分别为304 nm和350 nm两个吸收峰,源自于Ce^3+离子的4f→5d跃迁;光致发射谱和X射线激发发射谱都表现为典型的非对称双峰结构,归属于Ce^3+离子的5d^1→2F5/2和5d^1→2F7/2跃迁,Ce^3+离子的最佳掺杂浓度约为1%;荧光衰减时间约为37.2 ns,可满足高时间分辨X射线探测需要。     

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.     

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.     

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.     

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.     

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.