Four distinctive 1-D lanthanide carboxylate coordination polymers: Synthesis,crystal structures and spectral properties

Four novel lanthanide coordination polymers [Pr(mal)(OH)(bipy) · 2H₂O]_n (1), {[Dy¹(SBA)₃(H₂O)₂][Dy²(SBA)₃(H₂O)₂] · 4H₂O}_n (2), {[Tb(OHnic)(Onic)(H₂O)₅ · (OHnicH)] · H₂O}_n (3) and {[Sm(OHnic)(Onic)(H₂O)₅ · (OHnicH)] · H₂O}_n (4) (Hmal = maleic acid, HSBA = 4-sulfobenzoic acid, OHnicH = 6-hydroxynicotinic acid and bipy = 2,2′-bipyridine) have been synthesized and determined by single crystal X-ray diffraction. Complex 1 is a 1-D helical chain with seven-coordinated praseodymium centers. Complex 2 forms 1-D chain-like molecular structure containing two crystallographically unique dysprosium centers, the Dy¹ center is seven-coordinated while Dy² is eight-coordinated. The isomorphous complexes 3 and 4 exhibit an unprecedented 1-D chain-like polymeric structure through hydroxyl oxygen atoms of bridging Onic²⁻ anions linking up the neighboring central ions, and there exist three types of 6-OHnicH ligands in the structural unit which is rare for lanthanide carboxylate complexes. The photophysical properties of these complexes were studied using ultraviolet absorption spectra, fluorescence excitation and emission spectra.     

Chemometric analysis of disubstituent effects on the 13C chemical shifts of the carboxyl carbons (deltaCO) of benzoic acids. A comparative study of the substituent effects on the strength of benzoic acids in apolar aprotic media

The results of measurements of substituent induced chemical shifts of carboxyl carbons (deltaCO) of dichloro- and difluorobenzoic acids, including the monosubstituted ones with substituents at meta- and/or ortho- positions, in chloroform-d and strengths of these acids (log K) in chlorobenzene show an anomalous reverse trend between deltaCO and log K, while the electron density at carboxyl carbons should influence similarly both deltaCO and log K. A detailed chemometric analysis of comparison of disubstituent effects between deltaCO and log K on the basis of Fujita-Nishioka's multiparameter approach and assumption of additivity of substituent effects shows a dominance of the localized pi-polarization mechanism relative to simple electrostatic effects upon deltaCO. Further, steric factors play a significant role in determining deltaCO whereas with respect to log K they were insignificant. The overall anomaly has been rationalized keeping in mind that, while log K is a gross measure of energy differences between the ionized and unionized forms of the acids, deltaCO is a very sensitive probe for determining changes in electron density at the carboxyl carbon of the unionized acid.     

On the F. and M. Riesz theorem on wedges with edges of class <Emphasis Type="Italic">C</Emphasis><Superscript>1,α</Superscript>

This work extends the classical F. and M. Riesz theorem to measures that are boundary values of holomorphic functions defined on wedges in with edges that are in the class C ^1,α.This work was supported in part by NSF INT-0203005, CNPq and FAPESP     

三腔渡越管振荡器高频结构的解析研究

 从圆柱坐标系下Borgnis位函数的齐次标量Helmholtz方程出发,引入慢波驻波概念及其场表达式,利用Borgnis位函数的边界条件及相邻子区公共界面上的场匹配条件,导出了三腔渡越管振荡器内角向均匀TM模的色散关系及场分布的解析表达式。运用该解析法求得三腔渡越管振荡器的谐振频率与实验中测得的微波频率一致,求得的场分布与数值法得到的场分布十分吻合。     

局地强迫激发的非线性长波扰动

利用扰动法导得了非线性强迫Boussinesq方程,利用数值解讨论了地形和外源等局地强迫激发的非线性长波扰动的一般性状和时间演变特征,并对移动性孤波与地形的相互作用进行了分析研究。     

K-F系统中的波前相位调制与光强调制的转换

研究在由一薄片Ｋｅｒｒ 介质与一块二维反馈镜组成的非线性光学系统中光波前相位与光强的转换过程。根据基尔霍夫衍射定理,导出了单一模式以及小畸变近似条件下多个模式的相位－ 光强转换关系的方程。结果证明：通过衍射,入射波前相位各阶Ｚｅｒｎｉｋｅ 模式成分的大小转换为反馈光光强的非线性调制。     

双反射膜双频He-Ne激光器双频特性及偏振特性的实验研究

本文对 5 MHz频差双反射膜双频 He- Ne激光器输出激光的双频特性及偏振特性进行了实验研究。研究结果表明 ,当磁场方向同反射膜的一个本征模方向基本重合时 ,有双频出现 ;当磁场方向同反射膜的一个本征模方向夹角在 45°左右时 ,无双频出现。输出激光的偏振方向由反射膜的本征模确定 ,其偏振非正交程度为 tgρ≤ 0 .0 0 87,椭圆化程度tgβ随激光管与磁场的相对角位置变化而发生变化。在合适的位置 ,tgβ可以小至 2 / 70 0。该种外差光源具有较好的偏振特性。     

Stability of a Laser-diode-pumped Cr~(4 )∶YAG Passively Q-switched Nd~(3 )∶YAG Laser

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RESEARCH ON VIBRATION MODES OF THE CHINESE CHIME STONE

Nearfield acoustical holography is a powerful tool for imaging of acoustic sources. In this article, the basic theory treating steady-state acoustic radiation with generalized holography has been discussed. By holographic imaging, the vibration characteristics of irregular objects, the Chinese ancient musical instrument, the one-tone chime stone and the two-tone chime stone provided by the Institute of Archaeology, the Museum of Hubei Province, have been researched. The results show that the ancient chime stone has two main vibration modes, which make up the base of sound produced by the instrument. As for the two-tone chime stone, it is not so long and wide as the single-tone chime stone, but thicker and smoother than the single-tone chime stone. When it is excited at different positions, although it radiates sounds of different frequencies, its vibration modes are similar. This may be related to its dimensions and shape. The research is helpful for studying the sound producing system and the radiated field characteristics of the chime stone.     

Single-Mode Operation of Broad-Area Diode Laser at 670 nm by External Cavity Configuration with a Diffraction Grating

We demonstrate the single mode operation of a broad-area diode laser at 670 nm by means of an external cavity configuration using a diffraction grating. The output power of 150 mW is obtained with a spectral width of 40 MHz.