穆斯堡尔谱法及其应用

文章简介了穆斯堡尔效应、穆斯堡尔谱的产生以及穆斯堡尔效应的应用 ,说明它不仅在理论上具有深刻的意义 ,又有着广泛的应用价值 .     

超短脉冲贝塞尔光束的非近轴效应对传输的影响

 对超短脉冲贝塞尔光束在近轴近似和非近轴情况下自由空间中的传输作了研究。结果表明，其空间波形在传输中保持贝塞尔形状不变，不受非近轴效应影响；然而当空间参数较大时，非近轴效应影响超短脉冲贝塞尔光束的时间波形。     

Precise measurement of magnetic moment of short-lived β-emitting nuclei12B ( I π=1+, T 1/2=20.18 ms)

The spin polarized β-emitting nuclei¹²B (I ^π=1⁺,T _1/2=20.18 ms) were produced by the nuclear reaction¹¹B(d, p)¹²B and by the selection technique of the incident deuteron energy and the¹²B recoil angle following the nuclear reaction. The nuclear magnetic moment of the short-lived nuclei¹²B was measured by β-NMR with the β-NMR and β-NQR setup established for the first time in China. The nuclear magnetic moment of¹²B was determined to be μ=0.99993±0.00048 nm org=0.99993±0.00048 after the precise correction of the Knight shift.     

Writing Fiber Grating of Different Wavelength Using the Same Phase Mask

Chirped fiber grating was used in dispersion compensator. We tried to use the same phase mask to write fiber grating of different wavelength with two methods to reduce the price of the fiber grating.     

High temperature superconducting thin films for microwave filters

YBa₂Cu₃O_7-δ and Tl₂Ba₂CaCu₂O₈ thin films for microwave filters were synthesized by pulsed laser deposition and the two-step thalliation process. Substrate quality requirements and the relation of thin film morphology, microstructure with microwave surface resistance were discussed.     

COMPLETE EIGEN-SOLUTIONS FOR ANTI-PLANE NOTCHES WITH MULTI-MATERIALS BY SUPER-INVERSE ITERATION

In this paper,the super-inverse iterative method is proposed to compute the accurateand complete eigen-solutions for anti-plane cracks/notches with multi-materials,arbitrary opening an-gles and various surface conditions.Taking the advantage of the knowledge of the variation forms ofthe eigen-functions,a series of numerical techniques are proposed to simplify the computation andspeed up the convergence rate of the inverse iteration.A number of numerical examples are given todemonstrate the excellent accuracy,efficiency and reliability of the proposed approach.     

A new strategy for the synthesis of α,β-diaroylpropionates promoted by samarium metal in DMF

When promoted by samarium in DMF, aroyl chlorides react readily with acrylates to afford α,β-diaroylpropionates in good to excellent yields without pretreating or activating the metallic samarium.     

Triangular halogen trimers. A DFT study of the structure, cooperativity, and vibrational properties

Triangular halogen trimers (RX)3, where X = Br, I and R represents H, H3C, H2FC, HF2C, F3C, CH2=CH, CH[triple bond]C, and Ph, have been investigated using the density functional theory in the Perdew, Burke, and Ernzerhof method. We report herein the optimized geometries of the stable structures, their vibrational frequencies, and binding energies with the two- and three-body terms. All trimer structures possess a cyclic array of halogen atoms in the type II approach by virtue of the nonspherical atomic charge distribution around the halogens. The Br...Br interactions in trimers are very weak, whereas the I...I interactions in trimers are relatively stronger. While all bromine trimers and most of iodine trimers are predicted to be noncooperative, three of iodine trimers show weak cooperativity. The analysis of vibration modes reveals that all halogen trimers exhibit no especially remarkable frequency shifts. It is also shown that the electrostatic contribution plays a major role in the halogen...halogen interactions in halogen trimers. In contrast to bromine trimers, the relative contribution of charge-transfer component to the halogen...halogen interactions becomes more important for iodine trimers.