克尔磁光效应的经典理论分析

本文引入与自旋-轨道相互作用等有关的有效场概念,运用经典电磁场理论,推导了磁光克尔旋转的明确表达式.证明了各种磁光介质的极向克尔旋转θ_k的实部θ′_k和虚部θ″_k均与有效场H_i成正比,在铁磁性介质中近似与vM成正比,M为磁化强度,在亚铁磁性等介质中近似与(?)v_iM_i成正比,M_i为i次点阵的磁化强度.同时还证明了近似的横向克尔旋转θ_k~t与H_i~2正比;θ_k和θ_k~t的温度特性取决于H_i的温度特性.     

磁光Kerr效应的温度特性研究

从磁光Kerr效应的微观量子表述出发，分别研究了铁磁材料和亚铁磁材料的磁光Kerr效应的温度特性。结果表明，磁光Kerr转角θK与材料磁化强度随温度变化关系不同。铁磁材料θK对磁化强度M的级数展开式中仅含M奇次项。亚铁磁材料可以出现磁化强度M≠0而磁光Kerr转角θK=0情况。     

磁光玻璃费尔德常数的色散特性研究

本文对磁光玻璃的费尔德常数与工作波长的关系进行了理论分析和实验研究。首先由色散理论导出磁光玻璃的费尔德常数的波长依赖性，然后将ZF1、ZF6磁光玻璃加工成实验样品，测试了不同工作波长下的ZF1、ZF6磁光玻璃材料的费尔德常数，并将实验值和理论值进行了比较，分析误差产生的来源。在文章的最后，推导出费尔德常数的色散特性，讨论了磁光玻璃应用在磁光玻璃光纤电流传感器中存在的问题。     

斜向磁化的YIG波导中静磁波传播特性

分析了斜向静磁场作用下磁光薄膜波导中传播的静磁正向体波特性,计算了YIG薄膜波导中静磁波传播常数以及与磁光耦合系数相联系的动态磁化强度对静磁波模数、频率和斜向场等的依赖关系.计算表明：静磁波频率f及模数m越大、磁场H_i及其偏角θ越小,静磁波传播常数K_s越大;零模静磁体波的（动态磁化强度）振幅远大于高模数的静磁体波振幅.在适当的静磁体波频率范围内,斜向偏置磁场可提高静磁体波的振幅,进而可以改善静磁波与导波光的相互作用特性和提高导波光的衍射效率. 关键词：     

磁光非线性光纤中光参量增益的研究

将光纤中磁光效应和非线性效应作为微扰,推导了磁光四波混频的耦合模方程.通过解析解研究了各向同性磁光非线性光纤的参量过程,并指出利用磁光耦合系数的色散特性可以实现四波混频的相位匹配.同时,采用龙格-库塔法分析了在线双折射磁光非线性光纤中,忽略费尔德常量的波长依赖性时,左旋圆偏振光参量增益的磁控特性,指出了实验中采用较高费尔德常量的非线性光纤的必要性.研究表明:1)对于低线双折射磁光非线性光纤,优化双折射大小可以获得最大的参量增益;2)根据参量增益对磁光耦合系数的单调依赖特性,适当选择光纤长度、泵浦功率以及输入导波光的偏振态,可使参量增益的磁可调范围大大提高.     

顺磁性物质CeF3中磁化率和费尔德常数的定量计算

本文首先计及晶场对顺磁性物质CeF_3中Ce~(3+)离子4f基态和5d激发态能级的影响,进而考虑了间接交换作用有效场II_v和外磁场H_e共同作用下导致的晶场基态能级的进一步分裂,然后应用基态双能级跃迁模型定量计算了CeF_3中的比法拉第旋转θ_F,费尔德常数F和磁化率X以及它们与温度的依赖关系.计算表明,CeF_3中的磁光效应及其温度特性与Ce~(3+)离子之间的间接交换作用密切相关,在60相似文献   

法拉第旋转镜对旋转光纤磁光性能测量的影响

为了解决随机线性双折射对光纤磁光特性测量的影响,采用旋转光纤（SF）结合法拉第旋转镜（FRM）的测量方法,研究了FRM对旋转光纤磁光特性测量的影响。首先,从理论方面研究旋转光纤与FRM的引入如何减小光纤中的随机线性双折射对磁光特性测量的影响,并搭建基于FRM的旋转光纤磁光特性测试系统。当光源波长为1310 nm时,FRM作用前的旋转光纤费尔德常数都比未旋转光纤的大,且旋转光纤的节距越短,费尔德常数越大。特别是旋转光纤的节距为1.0 mm时,其费尔德常数为0.8304 rad/（T·m）,比未旋转光纤的费尔德常数[0.8029 rad/（T·m）]增大了约3.43%。当测试系统加入FRM后,不同光纤的费尔德常数测量值相较于未使用FRM的光纤费尔德常数测量值都有一定幅度的增大,尤其相比于节距为1.0 mm时的旋转光纤更进一步提高了7.50%,并且在FRM作用前后不同光纤费尔德常数测量值的均方差分别为0.99%和0.61%,说明FRM的引入提高了掺杂光纤费尔德常数的测量精度与稳定性。     

金属间化合物DyMn_2Ge_2的自发磁相变和场诱导的磁相变

在 10— 80 0K的温度范围内用X射线衍射方法测量了DyMn2 Ge2 化合物的晶格常数与温度的变化关系 ,观察到高温时DyMn2 Ge2 由顺磁状态到反铁磁状态的自发磁相变伴随着晶格常数a的负的磁弹性异常现象 .在4 2K— 2 0 0K的温度范围内测量了DyMn2 Ge2 的交流磁化率 .在交换相互作用的分子场模型近似下 ,从理论上分析讨论了DyMn2 Ge2 的低温自发磁相变和场诱导的磁相变 .计算了DyMn2 Ge2 单晶的磁化强度与温度的变化关系以及不同温度下外磁场沿晶轴c方向时的磁化曲线 .理论分析和计算结果表明 ,温度低于 33K时在DyMn2 Ge2 中观察到的场诱导的一级磁相变为由亚铁磁状态 (Fi)到中间态 (IS)相变 .     

基于法拉第磁光效应测量空间磁场

在法拉第效应中,线偏振光通过加有外磁场的磁光介质时,其光矢量发生了旋转.光的偏振方向旋转的角度与磁场沿着光波传播方向的分量呈线性正比关系,因此通过测量旋光角度即可得到相应的磁场大小.本实验创新性地提出基于法拉第磁光效应测量空间磁场的方法,利用了半影法减小测角器的测量误差,更加精准地找到了消光位置.实验测得实验室环境中空间磁场的磁感应强度B=0.287 mT,并得到磁偏角大小为θ=7.688°.与使用磁阻传感器进行测量的数据相比,磁感应强度的相对误差为η_B=4.6%,磁偏角的相对误差为η_θ=9.8%.     

磁光材料磁圆二向色性的测量

采用磁光旋转测量装置与1/4波片组合而成的实验装置测量了(BiTm)_3(FeGa)_5O_(12)单晶薄膜样品的磁圆二向色性(椭圆率tanhθ″),以及θ″与磁场强度H、样品厚度2h的关系。测量密度达0.01°。实验证明了磁光旋转的虚部θ″与实部θ′一样,是与磁化强度M相联系的,且随样品厚度线性增加。     

单链核糖体失活蛋白的Raman和红外光谱

我们测定了两种单链核糖体失活蛋白(肥皂草素和天花粉蛋白)的FTIR和FTRaman光谱。利用FTIR光谱酰胺Ⅲ区域对蛋白质的二级结构进行定量分析,计算了各种二级结构的含量。从肥皂草素和天花粉蛋白的二级结构分析可见,二者在结构上具有某种相似性,为二者功能上的相似性提供了依据。     

Geometry and Elasticity of Strips and Flowers

We solve several problems that involve imposing metrics on surfaces. The problem of a strip with a linear metric gradient is formulated in terms of a Lagrangian similar to those used for spin systems. We are able to show that the low energy state of long strips is a twisted helical state like a telephone cord. We then extend the techniques used in this solution to two–dimensional sheets with more general metrics. We find evolution equations and show that when they are not singular, a surface is determined by knowledge of its metric, and the shape of the surface along one line. Finally, we provide numerical evidence by minimizing a suitable energy functional that once these evolution equations become singular, either the surface is not differentiable, or else the metric deviates from the target metric.     

Equation of state and thermal expansivity of LiF and NaF

The high-pressure and high-temperature behaviors of LiF and NaF have been studied up to 37 GPa and 1000 K. No phase transformations have been observed for LiF up to the maximum pressure reached. The B1 to B2 transition of NaF at room temperature was observed at ～28 GPa, this transition pressure decreases with temperature. Unit-cell volumes of LiF and NaF B1 phase measured at various pressures and temperatures were fitted using a P–V–T Birch–Murnaghan equation of state. For LiF, the determined parameters are: α₀ = 1.05 (3)×10^?4 K^?1, dK/dT = ?0.025 (2) GPa/K, V ₀ = 65.7 (1) Å³, K ₀ = 73 (2) GPa, and K′ = 3.9 (2). For NaF, α₀ = 1.34 (4)×10^?4 K^?1, dK/dT = ?0.020 (1) GPa/K, V ₀ = 100.2 (2) Å³, K ₀ = 46 (1) GPa, and K′ = 4.5 (1).     

受控核聚变两大途径的对比与结合

目前人们探索受控核聚变主要是从两个方向着手：磁约束受控核聚变和惯性约束受控核聚变，但目前还无法判定到底哪一种途径更为可取，文章首先对这两种途径进行对比，指出各自的特点和困难，在此基础上提出了一种结构相对简单，成本相对较低的三轴六极磁镜系统设想，希望能将磁约束和惯性约束和惯性约束结合起来，以实现受控核聚变反应。     

Kinetics and mechanism of the reaction of alkoxymethylidene malonate and malononitrile with hydrazines and anilines

The kinetics and mechanism of the nucleophilic vinylic substitution of dialkyl (alkoxymethylidene)malonates (alkyl: methyl, ethyl) and (ethoxymethylidene)malononitrile with substituted hydrazines and anilines R¹–NH₂ (R¹: (CH₃)₂N, CH₃NH, NH₂, C₆H₅NH, CH₃CONH, 4‐CH₃C₆H₄SO₂NH, 3‐ and 4‐X‐C₆H₄; X: H, 4‐Br, 4‐CH₃, 4‐CH₃O, 3‐Cl) were studied at 25 °C in methanol. It was found that the reactions with all hydrazines (the only exception was the reaction of (ethoxymethylidene)malononitrile with N,N‐dimethylhydrazine) showed overall second‐order kinetics and k_obs were linearly dependent on the hydrazine concentration which is consistent with the rate‐limiting attack of the hydrazine on the double bond of the substrate. Corresponding Brønsted plots are linear (without deviating N‐methyl and N,N‐dimethylhydrazine), and their slopes (β_Nuc) gradually increase from 0.59 to 0.71 which reflects gradually increasing order of the C–N bond formed in the transition state. The deviation of both methylated hydrazines is probably caused by the different site of nucleophilicity/basicity in these compounds (tertiary/secondary vs. primary nitrogen). A somewhat different situation was observed with the anilines (and once with N,N‐dimethylhydrazine) where parabolic dependences of the kinetics gradually changing to linear dependences as the concentration of nucleophile/base increases. The second‐order term in the nucleophile indicates the presence of a steady‐state intermediate ‐ most probably T^±. Brønsted and Hammett plots gave β_Nuc = 1.08 and ρ = ?3.7 which is consistent with a late transition state whose structure resembles T^±. Copyright © 2013 John Wiley & Sons, Ltd.     

Infrared Spectra and Configuration of Anion Radical and Dianion of Benzil and Benzil-18o

Abstract

Infrared spectra of the products of one- and two -step reduction of both benzil and benzil-¹⁸0 have been investigated in dimethylsulfoxide-d₆ and tetrahydrofurane solutions. Anion-radicals have been obtained by electrochemical reduction of benzil and benzil-¹⁸0; dinegative ions have been prepared by reduction of the same ketones with potassium mirror in vacuo. The band assignment has been performed using the group vibrational concept and isotopic shift data. The previous assignment of the C[dbnd]O stretching band of benzil anion-radical-has been discussed and corrected. Two bands in the infrared spectra of benzil dianion have been found to be sensitive upon ¹⁸0 isotope labelling. This result certifies the presence of cis-configuration of benzil dianion in the investigated solutions. A decrease of ca. 290 cm-¹ has been found for vC[dbnd]O after the transformation of the neutral benzil into an anion-radical. Conversion of benzil anion-radical into dianion has been accompanied by an additional vC[dbnd]O downward shift of 105 cm^?1     

酸碱染料离子的缔合及等色化

本文阐述了等色染料离子对形成的实验方法,等色染料离子对的缔全机理及其形式,用吸收光谱的能级图,从电子理论角度论述了等色染料离子对的缔合效应等色化,溶剂效应等以化机理。列表示出等色染料离子对的高灵敏度,从而证明了等色染料离子对的萃取光度,浮选光度及萃取荧光光度法是高灵敏度和超灵敏度的新体系,为金属痕量和超痕量分析开辟了更为宽广的前景。     

“电路原理”、“信号与系统”和“自动控制原理”课程的整合与优化

"电路原理"、"信号与系统"和"自动控制原理"三门课程是光电信息科学与工程等专业的专业基础课。若分别采用各自独立的教学内容和方法,内容交叉、重复,浪费学时,没有从整个课程体系系统化的角度把握有关内容。因此,提出了适用于光电信息科学与工程等专业的以上三门课程的教学改革方案,从根本上系统地将这三门课程进行整合、优化为"电路、信号和控制系统"课程。在教学实践中,进行了有关内容的教学尝试,缩短了教学时间,提高了教学质量。     

Polarity of the Medium and Quenching of Fluorescence of Caratenoids and Phthalimides

The relation for the dependence of the rate of radiationless energy conversion of the S ₁ state k _q on the polarity of the medium, obtained previously by the author, has been used to interpret the known literature data on the lifetime of the S ₁ state of solutions of some caratenoids and phthalimides. It has been shown that in alcohols and water (normal and deuterated ones) the fluorescence quenching of 4-amino-, 4-methylamino-, and 4-dimethylamino-N-methylphthalimides (4AMP, 4MAMP, and 4DMAMP) as well as of peridinine in alcohols is due to H-bond formation. It has been established that a twofold increase in the number of amine atoms of hydrogen on passing from 4MAMP to 4AMP, as well as deuteration of solvents in the case of 4DMAMP, is followed by a decrease in k _q by a factor of 1.6 and 1.75, respectively. The mechanism of quenching in complexes formed with solvent molecules by means of the H-bond is discussed. It has been concluded that the quenching of fluorescence of phthalimides in such complexes is mainly due to the intersystem crossing initiated by the oscillations of the protons or deuterons of the H-bonds.