重掺镁LiNbO_3∶Fe晶体的光谱与光折变特性研究

研究了重掺镁LiNbO3∶Fe晶体的透射光谱与光折变特性 .结果表明 ,LiNbO3∶Fe晶体在重掺镁后 ,镁离子把晶体中的铁离子“挤”入铌位是重掺镁LiNbO3∶Fe晶体抗光折变的原因所在 .在重掺镁 (≥ 5mol% )LiNbO3∶Fe的晶体中 ,作为施主中心的Fe2 的特征吸收“台阶”的消失和 350 4cm- 1的OH吸收带的出现 ,都直接证明了铁离子从锂位进入了铌位 ,并以Fe3 Nb 的形式存在 .     

镁铁双掺杂LiNbO3晶体的光谱研究

测试了镁铁双掺杂LiNbO3晶体的紫外－可见和红外吸收谱，发现掺镁阈值以下的晶体在482．5nm处有一小吸收峰，认为是由晶体场引起的FeLi^3 离子d-d禁戒跃迁所至，在掺镁超过阈值的晶体中此峰趋于消失，说明Fe^3 离子掺镁阈值前后所处的晶体场发生了变化，进而推测了铁离子的占位发生了变化。结合OH^-谱3504cm^-1吸收带的出现，进一步说明了阈值以上Fe进入Nb位。     

LiNbO3：Fe晶体折射率调制度的实验研究

利用双光束干涉在不同掺Fe浓度的LiNbO3晶体中分别用红光和绿光写入光子晶格,研究了晶格周期Λ、掺Fe浓度、光波波长λ与光致折射率调制度Δn之间的关系.实验结果表明: 用红光(λ＝633nm)写入光子晶格,掺Fe浓度不大于0.05wt%,或用绿光(λ＝532nm)写入光子晶格,掺Fe浓度不大于0.03wt%时,LiNbO3晶体的光致折射率调制度Δn随晶格周期Λ的变化存在一个极大值,并随掺铁浓度的增加,相应的折射率调制度极大值也增大,并且向晶格周期小的方向移动,这与一中心模型理论得到的关系曲线的变化趋势相一致;若掺Fe浓度分别大于以上两值时,理论曲线与实验曲线完全不符,说明一中心模型的空间电荷场理论只适用于掺Fe浓度小的LiNbO3晶体.实验还发现LiNbO3:Fe晶体折射率调制度Δn与入光波长λ有关,对同一块晶体,绿光写入时折射率调制度比红光更大,且极大值向晶格周期小的方向移动也更大.     

双掺杂LiNbO_3晶体光谱和光折变特性

报道了双掺杂Ce :Fe ,Ce :Mn ,Mn :Fe生长态LiNbO3(LN)的光谱及光折变效应二波耦合增益特性 .研究表明 ,双掺杂浓度较高时 ,生长态的LiNbO3晶体的透过率光谱范围较小 ,光折变效应二波耦合增益较低 .几种双掺杂晶体都比单掺Fe晶体的光折变效应二波耦合增益低 ,表现出较强的抗光折变特性     

双掺杂LiNbO3晶体光谱和光折变特性

报道了双掺杂CeFe,CeMn,MnFe生长态LiNbO3(LN)的光谱及光折变效应二波耦合增益特性.研究表明,双掺杂浓度较高时,生长态的LiNbO3晶体的透过率光谱范围较小,光折变效应二波耦合增益较低.几种双掺杂晶体都比单掺Fe晶体的光折变效应二波耦合增益低,表现出较强的抗光折变特性.     

掺锌铌酸锂（LiNbO3：Zn）晶体的物性测量

本文配制了系列掺锌铌酸锂多晶料，测量了掺锌铌酸锂的熔化温度及居里温度随掺锌量的变化。用熔融提拉法生长了不同掺锌量的铌酸锂单晶。研究了锌在晶体中的分凝、晶体的抗光折变能力和倍频转换效率。实验结果表明：（１）在铌酸锂晶体中，随掺锌量的增加，ＬｉＮｂＯ３：Ｚｎ的熔化温度呈下降趋势，而居里温度线性上升。（２）在掺锌铌酸锂晶体中，调节锌的掺杂量，可以找到分凝系数近于１的掺锌浓度。（３）当掺锌量大于７ｍｏ１％时，ＬｉＮｂＯ３：Ｚｎ晶体与ＬｉＮｂＯ３：Ｍｇ具有同样的抗光折变能力，前者的倍频转换效率比后者稍大。     

重掺镁LiNbO3:Fe晶体的光谱与光折变特性研究

研究了重掺镁ＬｉＮｂＯ３：Ｆｅ晶体的透射光谱与光折变特性。结果表明,ＬｉＮｂＯ３：Ｆｅ晶体在重掺镁后,镁离子把晶体中的铁离子“挤”入铌位是重掺镁ＬｉＮｂＯ３：Ｆｅ晶体抗光折变的原因所在。在重掺镁（≥５ｍｏｌ％）ＬｉＮｂＯ３：Ｆｅ的 ,作为施主中心的Ｆｅ＾２＋的特征吸收“台阶”的消失和３５０４ｃｍ＾－１的ＯＨ吸收带的出现,都直接证明了铁离子从锂位进入了铌位,并以Ｆｅ＾３＋Ｎｂ的形式存在。     

近化学计量比掺铁铌酸锂晶体光折变中心的研究

对不同锂铌比的掺铁铌酸锂晶体的光折变光栅的写入与擦除过程进行了研究,发现单中心模型已经不适用于近化学计量比掺铁铌酸锂晶体的光折变过程.通过对光折变光栅的擦除曲线的拟合发现,近化学计量比掺铁铌酸锂晶体的擦除过程为双指数过程,说明对于近化学计量比掺铁铌酸锂晶体光折变中心为两种.     

Fe：LiNbO3晶体光折变效应的实验研究

研究经极化和还原处理后的Fe：LiNbO3晶体在调制光照射下,光激发自由载流子的空间电荷场形成的动态过程。并且通过研究晶体准击穿时的光折变和衍射光强随时间的变化关系,从实验上说明了Fe：LiNbO3晶体的光折变效应主要是由光生伏打效应决定的。     

Mn：Fe：LiNbO3晶体两波耦合温度特性实验研究

本文对30℃至120℃温度内的光折变晶体Mn:Fe:LiNbO3的前向双光束耦合的温度特性进行了实验研究，发现在50℃，70℃和105℃附近出现异常峰值。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with