Li/Nb摩尔比变化对Mg:Sc:Fe:LiNbO3晶体光折变性能的影响

掺入摩尔分数为1%MgO,0.5%Sc2O3和质量分数为0.03% Fe2O3,从Li与Nb摩尔比分别为0.85,0.94,1.05,1.20和1.38的熔体中用提拉法生长Mg:Sc:Fe:LiNbO3 (Mg:Sc:Fe:LN)晶体.测试了晶体的紫外-可见吸收光谱和红外光谱、抗光损伤能力、衍射效率、响应时间和光折变灵敏度.结果表明:随着Li/Nb摩尔比增加,Mg:Sc:Fe:LN晶体的吸收边发生紫移;n(Li)/n(Nb)=1.05的晶体分别在3 466,3 481 cm-1和3 504 cm-1处出现OH-吸收峰;n(Li)/n(Nb)=1.38的晶体在3 504 cm-1和3 535 cm-1处出现OH-吸收峰.随n(Li)/n(Nb)的增加,Mg:Sc:Fe:LN晶体的衍射效率减小,响应速度和光折变灵敏度增大.n(Li)/n(Nb)=1.05的近化学计量比Mg:Sc:Fe:LN晶体的抗光损伤能力最高.     

不同Li/Nb摩尔比In:Fe:LiNbO3晶体的生长及其光学性能

在LiNbO3(LN)中掺摩尔分数为1%的In和掺质量分数为0.03%的Fe,用提拉法技术生长具有不同n(Li)/n(Nb)[n(Li)/n(Nb)=0.94,1.05,1.20,1.38]的In:Fe:LN晶体.测试不同n(Li)/n(Nb)的In:Fe:LN晶体的吸收光谱、抗光致散射能力和指数增益系数,并计算晶体的有效载流子浓度.结果表明:晶体样品随着n(Li)/n(Nb)增加,吸收光谱的吸收边发生紫移,抗光致散射能力增加,指数增益系数和有效载流子浓度增大.采用n(Li)/n(Nb)=1.38的In:Fe:LN晶体作记录介质,n(Li)/n(Nb)=1.05的In:Fe:LN晶体作位相共轭镜进行全息关联存储实验.实验表明:存储系统具有实时处理,成像质量好,信噪比高和能反复使用等优点.     

掺镁近化学计量比铌酸锂晶体的生长

用改进的提拉技术从富锂[摩尔比n(Li2O)/n(Nb2O5)=58.5/41.5]熔体中生长了φ40mmx60mm的掺镁近化学计量比铌酸锂(LiNbO3)晶体.利用X荧光光谱分析了晶体中铌离子(Nb5 )和镁离子(Mg2 )的含量.通过紫外吸收和红外吸收峰研究了晶体中缺陷的结构,初步断定晶体中Mg2 的掺杂浓度已达到抗光伤阈值的浓度.生长晶体的比热容[O.69J/(g·K)]高于同成分LiNbO3晶体的比热容[O.64J/(g·K)].     

不同Li/Nb摩尔比In∶Fe∶LiNbO_3晶体的生长及其光学性能

在Li NbO3(LN)中掺摩尔分数为1%的In和掺质量分数为0.03%的Fe,用提拉法技术生长具有不同n(Li)/n(Nb)[n(Li)/n(Nb)=0.94,1.05,1.20,1.38]的In∶Fe∶LN晶体。测试不同n(Li)/n(Nb)的In∶Fe∶LN晶体的吸收光谱、抗光致散射能力和指数增益系数,并计算晶体的有效载流子浓度。结果表明晶体样品随着n(Li)/n(Nb)增加,吸收光谱的吸收边发生紫移,抗光致散射能力增加,指数增益系数和有效载流子浓度增大。采用n(Li)/n(Nb)=1.38的In∶Fe∶LN晶体作记录介质,n(Li)/n(Nb)=1.05的In∶Fe∶LN晶体作位相共轭镜进行全息关联存储实验。实验表明存储系统具有实时处理,成像质量好,信噪比高和能反复使用等优点。     

近化学计量比Fe:Mg:LiNbO_3晶体生长与其存储性能

在LiNbO3(LN)中分别掺入0.5%(摩尔分数,下同),1%和2% MgO,0.03%(质量分数)Fe2O3,配料中n(Li)/n(Nb)=1.38,采用顶部籽晶溶液生长法生长近化学计量比Fe:Mg:LiNbO3(near-stoichiometric Fe:Mg:LiNbO3,Fe:Mg:SLN)晶体。测试了晶体的红外光谱、抗光损伤能力和存储性能。结果表明:Fe:2%Mg:LN晶体的OH-吸收峰移到3535cm-1,抗光损伤能力比Fe:LN提高3个数量级。Fe:0.5%Mg:LN晶体的灵敏度、动态范围和抗光损伤能力比Fe:LN晶体分别高2.5倍,2倍和1个数量级。以Fe:2%Mg:LN晶体和Fe:LN晶体分别作为存储介质,进行大容量存储实验。在一个公共体积内实现1200幅体全息图的存储。Fe:2%Mg:LN晶体的存储质量优于Fe:LN晶体。     

Li/Nb摩尔比变化对Zr:Fe:LiNbO3晶体光折变性能的影响

同成分LiNbO3(LN)溶体中掺进摩尔分数为2%的ZrO2和质量分数为0.03%的Fe2O3,从不同Li/Nb摩尔比(0.94,1.05,1.20,1.38,0.85)熔体中用提拉法生长了系列Zr:Fe:LN晶体.测量了晶体的红外光谱、抗光损伤能力、指数增益系数和全息存储性能.结果表明:不同Li/Nb摩尔比的Zr:Fe:LN晶体红外光谱OH-吸收峰出现了3475,3478cm-1和3486cm-1 3个新峰.晶体的光折变性能都有不同程度的提高.近化学计量比Zr:Fe:LN晶体(Li/Nb的摩尔比为1.38)的抗光损伤能力比Fe:LN晶体提高2个数量级以上.指数增益系数是Fe:LN晶体的2倍,写入速度比Fe:LN晶体提高1个数量级,光折变灵敏敏度和动态范围皆提高4倍以上.近化学计量比Zr:Fe:LN晶体是优良的光折变和全息存储晶体材料.     

Ce:Fe:LiNbO3晶体的生长及光折变性能

在氧化锂(Li2O)摩尔分数(下同)为48.6%～58%的LiNbO3中掺入0.1%的氧化铈(CeO2)和质量分数为0.03%的氧化铁(Fe2O3),用提拉法技术生长出高光学质量的具有不同摩尔比n(Li)/n(Nb)的Ce:Fe:LiNbO3晶体.通过紫外-可见光谱和红外光谱测试了晶体样品的组成和缺陷结构.通过二波耦合实验系统研究了Ce:Fe:LiNbO3晶体样品的光折变性能.结果表明:晶体样品随n(Li)/n(Nb)比增加,样品的衍射效率降低,动态范围降低,但是,全息响应速率和光折变灵敏度提高.     

Mg:In:LiNbO3晶体波导基片光损伤性能研究

在LiNbO3中掺入3％MgO和1％In2O3(摩尔分数，下同)，采用Czochralski法生长了3％Mg：2％In：LiNbO3晶体。极化后，对晶体进行氧化和还原处理。利用光斑畸变法，测试了晶体在488．0nm波长下的抗光损伤能力，结果表明：Mg：In：LiNbO3晶体抗光损伤能力比LiNbO3晶体提高2个数量级以上。通过Li空位模型，研究了Mg：In：LiNbO3晶体抗光损伤能力增强的机理。利用苯甲酸质子交换法制备了几种晶体的光波导基片，并采用m—线法测试了y切型波导基片在632．8nm波长下的光损伤阈值，Mg：In：LiNbO3；光波导基片的抗光损伤能力也相应提高了2个数量级。     

In∶Yb∶Er∶LiNbO_3晶体的生长和光谱性能

采用提拉法生长了掺0.25%(摩尔分数,下同)Yb2O3,0.25%Er2O3和(0.5%、1.0%、1.5%)In2O3的3种同成分In∶Yb∶Er∶LiNbO3晶体。通过晶体的红外光谱,解释了In3+,Yb3+和Er3+在晶体中的占位,由于Yb3+和Er3+离子的掺入,在In∶Yb∶Er∶LiNbO3晶体中In3+既占据Li位又部分占据Nb位,使2%In∶Yb∶Er∶LiNbO3晶体达到阈值浓度。采用980nm二极管激光器测试了In∶Yb∶Er∶LiNbO3晶体上转换发射光谱。结果表明:晶体的绿光上转换发射中心波段位于525、550nm处,分别相应于Er3+的2 H11/2→4 I15/2跃迁和4 S3/2→4 I15/2跃迁;上转换红光发射中心波段在660nm处,对应Er3+的4 F9/2→4 I15/2辐射跃迁。In3+能提高Yb∶Er∶LiNbO3晶体的抗光损伤能力,改变Er3+和Yb3+的局部环境及Yb3+对Er3+的敏化作用,使得In∶Yb∶Er∶LiNbO3晶体发光性能改变。     

Li+掺杂对Ba(Mg1/3Nb2/3)O3∶Er3+荧光粉上转换发光性能的影响

采用溶胶凝胶法制备Li+掺杂Ba(Mg1/3Nb2/3) O3∶ Er3+荧光粉,研究了碱金属离子掺杂对Ba(Mg1/3Nb3)O3∶ Er3+荧光粉物相结构及发光特性的影响.结果 表明:Li+的引入弥补了空位缺陷,提高了稀土离子之间的能量传递效率;同时降低结构对称性,提高Er3+的4f能级跃迁概率;并且提高了荧光粉的结晶度.Li+掺杂提高了Ba(Mg1/3Nb2/3)O3∶Er3+荧光粉的上转换发光强度,当Li+掺杂浓度为3％(摩尔分数)时,上转换发光强度最高增强了4倍.     

Mo:Sb:PbWO_4闪烁晶体的生长与发光性能

采用坩埚下降法生长了Mo:Sb:PbWO4(Mo:Sb:PWO)晶体.通过透射光谱、X射线激发的发射谱、光产额和荧光寿命的测试,研究了Mo,Sb双掺杂对PbWO4晶体的光谱和闪烁性能的影响.结果表明:与未掺杂晶体相比,掺杂样品提高了PWO晶体在350～430 nm波段的透过率,消除了350nm吸收,吸收边变得陡峭并且向长波方向偏移.Mo:Sb:PWO晶体的发光谱存在400～650nm的宽带,发光主峰为510hm,发光强度得到提高.尺寸为10mm×10mm×20mm的Mo:Sb:PWO晶体样品,在1000ns的积分时间门宽内光产额最大值可达70photon-electrons/MeV,约为BhGe3O12(BGO)光产额的7.2%.光产额的提高主要来自于Mo:Sb:PbWO4晶体发光中的慢发光成分的增加.     

Generating Line Spectra from Experimental Responses. III. Interconversion between Relaxation and Retardation Behavior

Abstract

An algorithm is described which allows relaxation line spectra to be interconverted into retardation line spectra, and vice versa. The first line spectrum is generated from a given experimental response such as the relaxation modulus, the storage modulus, or the loss modulus, or from a response such as the creep compliance, storage compliance, or loss compliance. The interconversion algorithm is here applied to the standard linear solid and liquid models, and to a 32-line spectrum simulating the behavior of an entangled polymer.     

吡贝地尔的波谱学分析与结构确证

通过波谱学分析对吡贝地尔的化学结构进行确证。测定了吡贝地尔的高分辨质谱(HRMS)、核磁共振波谱(包括1 HNMR、13 CNMR、DEPT-135和HSQC)、质谱(MS)、紫外光谱(UV)、红外光谱(IR)等,并且对样品进行了差热分析(DSC)和热重分析(TGA)。对该化合物所有的1 HNMR和13 CNMR谱信号进行了归属,讨论了红外和紫外特征吸收峰所对应官能团的振动形式。对吡贝地尔的质量控制具有重要的参考价值。     

Trilayer Composite Poly(styrene/butyl acrylate/acrylic acid) Terpolymer Microspheres with Fe2O3 Middle Layer: Synthesis and Characterization

Fe₂O₃ particles with diameter of 3–5 nm were encapsulated in polymer spheres (styrene/butyl acrylate/acrylic acid terpolymer latex) by emulsion polymerization. Control of the pH value of the medium and modification of the latex prior to the second polymerization were of importance in determining the microstructure and morphology of the composite particles. The interaction between Fe₂O₃ and seed latex was confirmed by IR spectral changes of the surface groups of the latex particles. Mossbauer spectra gave evidence for the changes of electric density and electric field symmetry around Fe₂O₃, and surface photovoltage spectra indicated that the Fe₂O₃ particles were encapsulated in polymer. It was shown by all the results that the composite microspheres of size 80 nm had a core–shell structure with trilayers of seed latex core, Fe₂O₃ nanoparticles middle layer and polymer shell. © 1997 SCI.     

Photophysical properties of arylcarbonitrile derivatives: Synthesis, absorption and emission spectra, and quantum chemical studies

A new series of aromatic cyanovinyl compounds were synthesized via one-pot reactions of tri- or tetracyanoethylenes with nucleophilic reagents. The ground-state geometries and UV-vis absorption spectra of the compounds were computationally analyzed by means of density functional theory (DFT) and time-dependent density functional theory (TDDFT) calculations, respectively. None of the compounds were fluorescent in solution, but some showed intense emission in the solid state. The first excited singlet states (S₁) potential energy surfaces (PESs) were explored using complete active space SCF (CASSCF) calculations for the compounds in order to elucidate nonradiative decay mechanism that takes into account the involvement of conical intersections (CI).     

Structural optimization and vibrational analysis of an antidiabetic drug: tolbutamide

The purpose of this study is to investigate the vibrational spectrum of tolbutamide by ab initio techniques in combination with experimental studies. The Fourier transform infrared spectra (400–4000?cm^?1) and Laser-Raman spectra (100–4000?cm^?1) of tolbutamide have been obtained in the solid phase. Assignments have been found by the combination of the vibrational frequencies and the contribution of the potential energy distributions. Assignments have been compared with the theoretical and experimental results of similar structures as reported in the literature. Structural parameters such as bond lengths and angles, frequencies and infrared intensities and Raman activities of tolbutamide have been computed by density functional theory and Hartree–Fock methods using 6–311G++(d,p) and 6–31G(d) basis sets. The computed vibrational frequencies and optimized structural parameters are consistent with the corresponding experimental results. In addition, the images of tolbutamide frontier molecular orbitals (highest occupied and lowest unoccupied) and its energy gaps have been interpreted with the assistance of quantum chemical calculations.     

CaxSr1-xS:Mn的微波快速制备及其荧光光谱特性

目的:微波快速制备复合基质荧光体CaxSr(1-x)S:Mn,测定其荧光光谱并研究它们随基质摩尔掺杂比x(即Ca2 /Ca(2 ) Sr2 )值由1逐渐减小到0的变化,探求制备荧光颜色可调的荧光体的原理。方法:微波快速加热法。内容:通过XRD的测定,确定了含有不同x值的CaxSr(1-x)S:Mn的晶相。测定荧光光谱,研究它们随x值的变化趋势。结论:随着x值由1逐渐减小到0,荧光体CaxSr(1-x)S:Mn由单一的CaS相转变为CaS和SrS的混合相再逐渐变为SrS相,其荧光光谱也由CaS的特征光谱逐渐转化为SrS的特征光谱。根据CaxSr(1-x)S:Mn的发射波长与x值基本呈线性关系,可通过调节基质掺杂比,制备荧光颜色可调的荧光体。     

生长和退火气氛对Cr：Mg2SiO4晶体光谱的影响

在不同氧含量的气氛中生长了Ｃｒ：Ｍｇ２ＳｉＯ４晶体，研究了生长及退火气氛对晶体光谱的影响。实验表明，提高生长气氛中的氧含量，有利于４价Ｃｒ离子的形成。调节生长气氛中的氧含量，可以改变所生长晶体的荧光光谱，以满足可调谐激光的要求。晶体的退火实验表明，退火气氛对晶体光谱也有明显影响。研究结果有助于进一步加强对该晶体发光中心及其作用机理的认识。     

Sensing spectral stimuli: Sensor functions and number

Using synthesized and real spectra this article addresses questions regarding the degree to which synthetic and real sensor systems with one, two, and three sensors can distinguish among stimuli and can reconstruct the original spectra. Based on 64 synthetic spectra, the trichromatic sensors L , M , S distinguish the spectra at the level of 85% of the optimal result but reconstruct them only at the level of 70%. For symmetrical and symmetrically placed sensors the corresponding values are 76 and 94%. The conclusion is drawn that distinguishability was a more important goal of evolution than reconstructability. © 2005 Wiley Periodicals, Inc. Col Res Appl, 31, 30–37, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20171     

Bi0.6Ca0.4Mn0.2Fe0.8O3的介电性能研究

用溶胶-凝胶法制备了Bi0.6Ca0.4Mn0.2Fe0.8O3样品,通过检测样品的X衍射、介电谱和阻抗谱,对其微观结构和介电性能进行了研究.研究表明:随着频率的增加,样品的介电常数逐渐减小,而随着温度的增加,样品的介电常数逐渐加大.同时发现,通过在Bi0.6Ca0.4MnO3的Mn位进行Fe掺杂,明显的改善了Bi0....