Probing Structural Compositions of Porous Media with Two-dimensional Nuclear Magnetic Resonance

Combination of two-dimensional nuclear magnetic resonance (2-D NMR) correlation maps and a simple three-component model are proposed here to identify the structural composition of porous media. Homogeneous magnetic field and field with constant gradient of a novel Halbach sensor are employed for respective relaxation and diffusion measurements. NMR results are compared and confirmed with independent measurements on a scanning electron microscope and by energy dispersive spectrometer methods.     

Synthesis and structural characterization of Znb3Nb2 powder

Science China Physics, Mechanics & Astronomy - Zinc nitride (Znb3Nb2) powder has been synthesized through the nitridation reaction of Zn powder with NH3 gas (at the flow rate of 500 ml/min) at...     

超大规模集成电路互连电迁移自由体积电阻模型

将晶核析出的Avrami 方程应用于描述超大规模集成电路中金属Al薄膜互连电迁移过程中电阻的演变. 根据电子散射理论，晶界电阻主要起源于晶界处空位或者空洞对电子的散射. 为了描述这些离子的特征，引入了自由体积的概念，将晶界处电子散射这个复杂的过程简化用自由体积的有效散射截面来描述，从而建立了自由体积与电阻变化的定量关系，统一描述了电迁移过程中不同阶段的电阻变化. 数值模拟结果表明，在第一个空洞成核时刻电阻会发生急剧变化，这一结果已被实验所证实. 关键词： 电迁移 Al互连 电阻变化     

ASYMPTOTIC THEORY FOR A RISK PROCESS WITH A HIGH DIVIDEND BARRIER

A modified classical model with a dividend barrier is considered. It is shown that there is a simple approximation formula for the time of ruin when the level of dividend barrier is high and the claim sizes have a distribution that belongs to S（γ） with γ 〉0.     

Study on the Interaction between CdSe Quantum Dots and Bovine Serum Albumin with Ultraviolet Visible Absorption Spectroscopy

QDs (also called semiconductor nanocrystallines) were attracted considerable attention in the past decade1, 2. They have been used as luminescent probes in biology, medicine and more recently in analytical chemistry3-5. The interaction between QDs and ino…     

拟Fuchs群的收敛指数

根据H2上的双曲距离在拟共形变换下的拟不变性,给出了K-拟共形抛物循环Fuchs群的收敛指数的估计．     

非线性光学及其若干新进展

扼要介绍了非线性光学的基本概念及其最近10年来在飞秒激光，半导体材料，光纤通信和光信息存储等若干方面的研究进展。     

Induced electronic interactions in Chern-Simons systems

The induced electronic interactions in (1+2)-dimensional vector Chern-Simons systems are studied by means of path-integral quantization. We consider four cases: relativistic, and nonrelativistic fermion Maxwell-Chern-Simons models, and relativistic and nonrelativistic fermion Chern-Simons models. It is shown that the Chern-Simons term may induce exotic electronic interactions which can be local or nonlocal and small Chern-Simons coupling may have a considerable effect in some cases.     

Recombination measurements at low energies with Au49+,50+,51+ at the TSR

Recombination of Au⁴⁹⁺, Au⁵⁰⁺, and Au⁵¹⁺ ions has been studied at the TSR. With Au⁵⁰⁺ ions a storage lifetime of only 2 to 4 s was observed with the magnetically expanded electron beam of the cooler at a density of n_e = 10⁷ cm^-3. This short storage time is a consequence of the highest recombination rate coefficient ever observed with an atomic ion (1.8·10^-6 cm³ s^-1 at zero relative energy E_rel = 0 between electrons and ions). At about 30 meV a huge dielectronic recombination resonance is found with a record small width of only about 15 meV. Such resonances fortuitously occurring near E_rel=0 are probably the main reason for the enhanced recombination rates observed with Au⁵⁰⁺, with Pb⁵³⁺ (in a recent experiment at LEAR) as well as with other complex ions. For Au⁴⁹⁺ and Au⁵¹⁺ the recombination rates are smaller by an order of magnitude. This revised version was published online in August 2006 with corrections to the Cover Date.     

Measurement of field effects on dielectronic recombination of Si11+ ions

Cross sections for dielectronic recombination can be influenced by the presence of external electric fields in the electron--ion collision region. In most of the previous experiments with multiply charged ions such fields were present but unknown. Therefore, comparisons of experimental results with theoretical calculations were ambiguous: for obtaining best possible agreement, theory could use the field strength as a free parameter to adjust the calculated cross sections to the experiment. In recent measurements with 10 MeV/u Si¹¹⁺ ions stored in CRYRING, controlled external motional electric fields up to 183 V/cm were introduced in the electron cooler. Significant cross section enhancements were found for Rydberg states n > 20. This revised version was published online in August 2006 with corrections to the Cover Date.