NIR FT－Raman研究铝酸钠溶液的碳酸化过程

本文用ＮＩＲＦＴ－Ｒａｍａｎ光谱仪原位跟踪了铅酸钠溶液的碳酸化过程，观察到此过程的Ｒａｍａｎ光谱呈现振荡现象和非重线性，认为在碳酸化过程中，可能产生Ａｌ２（ＯＨ）离子和进一步缩聚形成的离子。     

非傍轴平顶高斯光束M2因子两种定义的比较研究

基于功率密度的二阶矩方法，推导出了非傍轴平顶高斯(FG)光束束宽和远场发散角的解析表达式.研究表明，当w0/λ→0时，远场发散角趋于渐近值θmax=63.435°，与阶数无关.使用非傍轴高斯光束代替傍轴高斯光束作为理想光束，研究了非傍轴FG光束的M2因子，并与传统定义的M2因子作了比较.在非傍轴范畴，非傍轴FG光束的M2因子不仅与阶数N有关，而且与w0/λ有关.按照定义，当w0/λ→0时，非傍轴FG光束的M2因子不等于0，对阶数N=1, 2, 3时，M2因子分别趋于0.913,0.882和0.886.当N→∞时，M2因子取最小值M2min=0.816.     

LD抽运Cr~(4 )∶YAG高重复率被动调QNd∶YVO_4激光器

采用Cr4 ∶YAG晶体作为可饱和吸收体,实现连续激光二极管(LD)端面抽运的Nd∶YVO4激光器的高重复率被动调Q·在注入抽运功率为8.8W时,得到重复频率23.8kHz、平均功率1.21W的调Q脉冲序列;每个脉冲能量为51μJ、脉宽为25ns、峰值功率达到2.03kW·实验上研究了脉冲重复频率、平均输出功率、脉冲宽度、单脉冲能量与抽运功率、输出镜透过率的关系·实验结果表明,当抽运功率较大时,脉冲重复频率和输出平均功率随着抽运功率的增加而减小,对此进行了合理的理论解释·     

纳米TiO_2∶Zn薄膜电极紫外光电特性研究

采用sol-gel法制备了Zn2 掺杂的锐钛矿相纳米TiO2薄膜电极.通过光电流作用谱和电流-电位(I-U)曲线研究了掺杂不同浓度Zn2 的TiO2薄膜电极的光电特性.由光电流作用谱可知,Zn2 的掺杂可显著影响薄膜电极的光电流大小,且掺杂的最佳浓度与薄膜晶粒尺度有关.在320nm单色光照射下,掺杂浓度(摩尔浓度)为0.1%的薄膜电极光电流最大,与未掺杂的本征薄膜电极相比增幅达40%.I-U曲线表明,光照下,随电极电位由正到负逐渐降低,不同掺杂浓度的TiO2薄膜电极中均出现了阳极电流向阴极电流转换的现象,且Zn2 掺杂浓度可影响电极阳极电流的初始电位.另外,无光照的暗态下,各薄膜在负电位区域观察到了相似的随电位降低而迅速增大的阴极暗电流.     

Spurious Shell Closures in the Relativistic Mean Field Model

Following a previous systematic theoretical study of the ground-state properties of over 7000 nuclei from the proton drip line to the neutron drip line in the relativistic mean field model [Prog. Theor. Phys. 113 （2005） 785], which is in fair agreement with existing experimental data, we observe a few spurious shell closures, i.e. proton shell closures at Z = 58 and Z = 92. These spurious shell closures are found to persist in all the effective forces of the relativistic mean field model, e.g. TMA, NL3, PKDD and DD-ME2.     

钐(Ⅱ)类卡宾CH_3SmCH_2X(X=Cl、Br和Ⅰ)促进乙烯环丙烷化反应途径的理论研究(英文)

用密度泛函B3LYP方法研究了过渡金属钐类卡宾与乙烯的环丙烷化反应的机理。对三种不同的钐的SS试剂CH_3SmCH_2X(其中X=Cl、Br和Ⅰ)分别和CH_2CH_2反应的各反应物、中间体、过渡态和产物构型的全部结构几何参数进行了优化,用内禀反应坐标(IRC)计算和频率分析方法,对过渡态进行了验证。结果表明：CH_3SmCH_2X(其中X=Cl、Br和Ⅰ)与CH_2CH_2环丙烷化反应按亚甲基转移通道(通道A)和卡宾金属化通道(通道B)都可以进行,与锂类卡宾的反应机理相同,只是按亚甲基转移通道(通道A)进行反应较容易一些,而且此反应在较低的温度下就可以发生。     

退火温度对YBa2Fe3O8的结构与磁性质影响分析

YBa2Fe3O8(YBFO)是具有三方钙钛矿结构的反铁磁(AFM)体,研究它的结构和磁性质对于我们认识三方钙钛矿结构具有重要作用.目前,关于固相法制备YBFO中退火温度方面的研究并不多,而控制退火温度是这种工艺中的重要环节.为制备高含量的YBa2Fe3O8,本文分别在760℃、950℃和1100℃退火温度下,采用固相...     

The sloshing of stratified liquid in a two-dimensional rectangular tank

The sloshing of inviscid liquid of stratified density in a rectangular tank is analyzed.As the flow is no longer irrotional,the governing equation is found to be quite different from the Laplace equation used for the liquid of constant density.In particular it contains terms of mixed temporal and spatial derivatives.The problem is solved based on the variable separation method and Laplace transform for the constant Vaisala-Brunt frequency.It is found that the stratification of density may have small effects...     

Design and end chamfer simulation of PEFP beam line curved dipole magnets

The design, fabrication and field measurement of 11 DC curved dipole magnets for the PEFP Beam Line have been completed. In this paper, a design method for a complex end chamfer using OPERA-3D is proposed. The conventional method for estimating chamfer shape is extended and applied to a curved dipole magnet by a coordinate transformation. Using the interface with CAD software, the complex end chamfer is modeled and fully determined by 3D simulation to meet the field uniformity requirement. The magnetic field measurement results are in good agreement with the simulation. The design considerations, field simulation results, end chamfer development process and measurement results are presented in detail.     

耦合微盘及带输出波导的单微盘腔的耦合模式特性

光学微腔具有很高的品质因子和很小的模式体积,在光电子器件研究方面具有重要的应用价值.运用时域有限差分(FDTD)法和Padé近似频谱分析法模拟研究了耦合微盘及带输出波导的单微盘微腔由于空间对称性破坏导致的模式耦合现象;特别计算了耦合模式的场分布和品质因子,并由场分布得出不同角量子数模式的能量比例.对耦合微盘,模式耦合引...