氰根桥联FeⅢ-CuⅡ一维配合物{[Fe(1-CH3im)(CN)4(μ-CN)Cu(cyclam)]·H2O}n的合成、结构及磁性研究

基于构筑单元K2[Fe(1-CH3im)(CN)5]和[Cu(cyclam)](ClO4)2,合成了一个氰根桥联FeⅢ-CuⅡ中性一维化合物{[Fe(1-CH3im)(CN)4(μ-CN)Cu(cyclam)]·H2O}n(1-CH3im=1-甲基咪唑;cyclam=1,4,8,11-四氮杂环十四烷)(1),并通过X-射线单晶分析表征其结构特征。结果表明:化合物(1)是由氰根桥联的杂金属组成的聚合物,其结构属于三斜晶系,P1空间群,a=0.832 56(17)nm,b=0.899 38(18)nm,c=0.998 3(2)nm,α=111.94(3)°,β=95.06(3)°,γ=116.90(3)°,V=0.587 7(2)nm3,Z=1,Dc=1.554 g·cm-3,μ=1.558 mm-1,F(000)=286,R1=0.051 9,wR2=0.135 3。磁性研究表明:配合物1中CuⅡ和低自旋的FeⅢ离子之间存在弱的铁磁耦合作用。     

基于二氰根铬的一系列氰根桥联CrⅢ-CuⅡ-CrⅢ三核配合物的合成、结构与磁性

基于一系列二氰根铬与[Cu(cyclam)](ClO₄)₂反应合成了3个氰根桥联Cr^Ⅲ-Cu^Ⅱ-Cr^Ⅲ三核配合物[Cu(cyclam)][Cr(bpmb)(CN)₂]₂·4H₂O(1)(cyclam=1,4,8,11-四氮杂环十四,bpmb^2-=1,2-二(2-吡啶甲酰胺基)-4-甲基苯),[Cu(cyclam)][Cr(bpdmb)(CN)₂]₂(2)(bpdmb^2-=1,2-二(2-吡啶甲酰胺基)-4,5-二甲基苯)和[Cu(cyclam)][Cr(bpClb)(CN)₂]₂·4H₂O(3)(bpClb^2-=1,2-二(2-吡啶甲酰胺基)-4-氯苯)。单晶衍射结果表明:3个化合物是结构类似的中性三核配合物,均含有氰根桥联的Cr(Ⅲ)-CN-Cu(Ⅱ)-NC-Cr(Ⅲ)连接;磁性研究表明:氰根桥在Cr^Ⅲ和Cu^Ⅱ离子间传递弱的铁磁耦合作用,基于自旋哈密顿算符Ĥ=-2J_CrCuŜ_Cu(Ŝ_Cr1+Ŝ_Cr2)拟合得到它们的磁耦合常数分别是J_CrCu=1.53(2) cm^-1(1),0.45(1) cm^-1(2)和0.73(2) cm^-1(3)。     

取代脂环烃物理化学性质的拓扑化学研究

为了探讨有机化合物的分子结构与理化性质的关系,作者在以前的工作基础上,基于一阶分子连通性拓扑指数构建了一个信息拓扑指数.将拓扑指数与取代脂环烃系列分子的气态标准生成热、气态标准熵、气态标准生成自由能、沸点、临界温度、临界压力、临界体积、汽化热、密度、热容及表面张力等十一种热力学性质及物理化学性质相关联,用一个通用公式对各类性质进行概括,然后用已有的实验数据与拓扑指数进行回归分析,得到一系列计算各性质的经验公式.回归结果发现,分子的理化性质与拓扑指数有较好的相关性,有5类性质的复相关系数大于0.99.用经验公式对各类性质进行重新计算,其结果与实验值比较符合,用实验值对计算值作图,发现各数据点紧靠对角线,说明误差较小.残差分布呈正态分布.     

Volt-ampere characteristics of a nitrogen DC plasma arc with anode melting

The characteristics of a nitrogen arc using a graphite cathode and a melting anode in a pilot-scale plasma furnace are investigated. The voltage is examined as a function of current and apparent plasma length. The voltage increases non-linearly with the increase of apparent plasma length, with the current fixed. The experimental data so obtained are compared with the predictions of the Bowman model for the electric arc, and with numerical simulations as well. The level of agreement between the experimental data at the melting anode and the numerical predictions confirms the suitability of the proposed the Bowman model. These characteristics are relevant to the engineering design and evaluation of a DC plasma furnace and reactor for the treatment of hazardous fly ash waste.     

从“海之子”到渔业巨子

13岁在人家的船上当水手;24岁驾着自己的船去闯天下;30年后,法国渔民的儿子米歇尔·阿德里安成为塞内加尔最大渔业公司的老板;今天,他的产业已横跨三大洲。     

电场调谐InAs单量子点的发光光谱

采用稳态和时间分辨发光光谱,研究了生长在p-i-n二极管结构内的InAs单量子点发光光谱的电场调谐特性.随着电场强度的增加,观察到量子点中激子发光的Stark 效应.通过选择不同波长的激光线激发量子点样品,发现随着电场强度的增加导致量子点发光强度的减弱,这是由于量子点俘获载流子概率的减小所致,而激子寿命的增加源于电场导致激子的Stark效应. 关键词： InAs单量子点 Stark效应 电子-空穴分离     

Experimental design to measure the anchoring energy on substrate surface by using the alternating-current bridge

The anchoring property of the substrate surface of liquid crystal cells plays an important role in display and nondisplay fields. This property directly affects the deformation of liquid crystal molecules to change the phase difference through liquid crystal cells. In this paper, a test method based on the alternating-current bridge is proposed to determine the capacitance of liquid crystal cells and thus measure the anchoring energy of the substrate surface. The anchoring energy can be obtained by comparing the capacitance–voltage curves of twisted nematic liquid crystal cells with different anchoring properties in experimental and theoretical results simulated on the basis of Frank elastic theory. Compared with the other methods to determine the anchoring energy, our proposed method requires a simple treatment of liquid crystal cells and allows easy and high-accuracy measurements, thereby expanding the test ideas on the performance parameters of liquid crystal devices.     

Single-Photon Emission from a Single InAs Quantum Dot

Excitation power-dependent micro-photoluminescence spectra and photon-correlation measurement are used to study the optical properties and photon statistics of single InAs quantum dots. Exciton and biexciton emissions, whose photoluminescence intensities have linear and quadratic excitation power dependences, respectively, are identified. Under pulsed laser excitation, the zero time delay peak of second order correlation function corresponding to exciton emission is well suppressed, which is a clear evidence of single photon emission.     

无界问题自然边界元与有限元的迭代耦合

根据区域分解算法的思想,研究了自然边界元与有限元耦合法的D-N迭代原理,并编写了耦合法计算程序,求解了带方孔的无界平面弹性问题。算例计算结果表明:当计算半径R取为孔洞尺寸的1.2倍,耦合法网格划分时取144个节点即可较好的逼近收敛值,而相同收敛效果有限元网格划分时需取272个节点。并且,在迭代过程中,松弛因子的选取对迭代收敛速度的影响很大,当松弛因子取0.2时,迭代收敛速度最快。     

Diode End-Pumped Passively Q-Switched Nd^3＋：GdVO4 Self-Raman Laser at 1176 nm

A compact diode-end-pumped passively Q-switched Nd^3＋ ：GdVO4/C^r4＋ ：YAG self-Raman laser at 1176 nm is demonstrated. When the To = 80% Cr^4＋：YAG saturable absorber is inserted into the cavity, the maximum Rtaman laser output reaches 175 mW with 3.8 W incident pump power. The optical conversion from incident to the Raman laser is 4.6% and the slope efficiency is 6.5%. The pulse energy, duration, and repetition frequency of the first stokes laser are 4.5μJ, 1.8 ns, and 38.5 kHz, respectively. There is strong blue emission （about 350- 400nm） can be observed in the Nd^3＋ ：GdVO4 crystal when the process of stimulated Raman scattering occurs, which is induced by the upconversion of the Nd^3＋ ions.