Theoretical research on enhancement of gain for Ni-like Ag 13.9nm x-ray laser using a new two-layer target

For experiments such as on Ni-like Ag x-ray laser, driven by 1\omega laser, the gain region is only several~nm depth near the target surface, this paper proposes a new two-layer target, in which a thin layer (several nm depth) of silver is plated on the surface of some other materials. Furthermore, the Ni-like Ag 13.9~nm x-ray laser produced by three new kinds of two-layer target with CH, Al and Ge as foundation, was theoretically studied.     

Evaporation induced diameter control in fiber crystal growth by micro‐pulling‐down technique: Bi4Ge3O12

Diameter self‐control was established in Bi₄Ge₃O₁₂ fiber crystal growth by micro‐pulling‐down technique. In accordance with Bi₂O₃‐GeO₂ phase diagram, the diameter was controlled due to compensation of solidification with evaporation of volatile Bi₂O₃ self‐flux charged into the crucible with excess. The crucibles had capillary channels of 310 or 650 μm in outer diameter. The crystals up to 400 mm long and 50‐300 μm in diameter were grown at pulling‐down rates of 0.04‐1.00 mm/min. The melt composition and the pulling rate were generally only two parameters determining solidification rate. As a result, crystals with uniform (± 10%) diameter and aspect ratio up to 10⁴ were produced without automation of the process. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

退火温度对镶嵌于SiO2膜中的Ge纳米晶结构的影响

采用磁控溅射及退火的方法制备了含Ge纳米晶的SiO2复合膜,应用拉曼散射和X射线衍射技术研究不同退火温度下的Ge纳米晶结构.结果表明:Ge纳米晶的结晶温度约为750 ℃.运用声子限域模型(RWL model)对样品的拉曼散射光谱进行拟合,确定出样品中Ge纳米晶的尺寸.通过XRD谱计算复合膜的内部压应力,得出由其引起的拉曼峰位的蓝移量,得出结论:压应力是造成拉曼模拟曲线与实验曲线峰位偏离的主要原因.     

Density functional theory and Hartree–Fock-density functional theory calculations of O, S, and Ge quadrupole coupling constants

The performance of several density functional theory and Hartree–Fock density functional theory methods in conjunction with Pople type bases for the calculation of ¹⁷O, ³³S, and ⁷³Ge quadrupole coupling constants in gaseous state molecules was investigated.Assessment of the several models was made by linear regression analysis of the calculated gradient of the molecular electric field versus the experimental nuclear quadrupole coupling constant (NQCCs). Calculations for oxygen on six molecules with the B3LYP/6-311++G(3df,3p) model yield a residual standard deviation of 0.057 MHz (1.4%); for sulfur on 12 molecules with the B3LYP/6-311G(3df,3p) model, 0.42 MHz (1.8%); and for germanium on nine molecules with the B3P86/6-311G(2d) model, 0.83 MHz (1.0%).In the case of germyl acetylene, our calculations indicate that the experimental NQCC reported some time ago by Thomas and Laurie [J. Chem. Phys. 44 (1966) 2602] was incorrectly assigned with respect to algebraic sign.Predictions are made of the ¹⁷O and ³³S NQCCs in furan, 4H-pyran-4-one, 4H-pyran-4-thione, and 4H-thiapyran-4-thione; and of the ⁷³Ge NQCC in germyl bromide.     

Dependence of the lidar signal depolarization on the receiver’s field of view in the sounding of fog and clouds

We report an experimental study of the lidar signal depolarization as a function of the relative contribution of the multiple scattering in case of optically dense objects in the atmospheric planetary boundary layer. Results of the observation of fog and stratus clouds are presented, as well as those obtained by sounding of stratocumulus clouds during a snowfall. The lidar data point to a rise of the depolarization coefficient as the influence of the multiple scattering increases in consequence of both viewing angle enlargement and penetration into the object sounded. The variations of the depolarization coefficient are studied as a function of the field of view. In the case of fog, this dependence is approximated by a three-parameter exponential law; it is found that the depolarization increases steeply when the viewing angle is increased from 9 mrad to 12.5 mrad. The relationships between the approximation parameters and the microphysical characteristics of the scattering medium are considered. The experimentally determined size of the area where multiple scattering occurs is in good agreement with that calculated according to the diffusion model. The results obtained on the multiple scattering effect on the depolarization can also be employed in determining the extinction coefficient profiles in optically dense objects, as well as in evaluating the characteristic size of the scattering particles. Received: 6 September 1999 / Revised version: 7 February 2000 / Published online: 6 September 2000     

阻抑过氧化氢氧化甲基橙退色反应分光光度法测定Ge-132

基于微量 Ge- 1 32对过氧化氢氧化甲基橙退色反应有阻抑作用 ,提出了阻抑退色光度法测定微量Ge- 1 32的新方法。该方法线性范围为 6 .88— 2 4.0 8μg/m L。用于模拟样品的测定 ,回收率在 93%— 99%范围内。     

Speculative trading: the price multiplier effect

During a speculative episode the price of an item jumps from an initial level p₁ to a peak level p₂ before more or less returning to level p₁ . The ratio p ₂/p ₁ is referred to as the amplitude A of the peak. This paper shows that for a given market the peak amplitude is a linear function of the logarithm of the price at the beginning of the speculative episode; with p₁ expressed in 1999 euros the relationship takes the form: ; the values of the parameter a turn out to be relatively independent of the market considered: , the values of the parameter b are more market-dependent, but are stable in the course of time for a given market. This relationship suggests that the higher the stakes the more “bullish” the market becomes. Possible mechanisms of this “risk affinity” effect are discussed. Received 29 September 1999     

裴景福及其《壮陶阁书画录》

裴景福,作为晚清民国时期来自安徽霍邱的一位名人,三十二岁（1886）即登进士第。历任广东陆丰、番禺、潮阳、南海县令,因事得罪岑春煊而被其以＂贪赃罪＂参劾,以致谪戍新疆,后经查无果而得恩赦。进入民国后,任安徽省公署秘书长,后擢升政务厅长。景福嗜收藏,精通鉴赏。其主要作品有：《河海昆仑录》、《睫闇诗钞》、《壮陶阁书画录》等。主要介绍了这位皖籍名人的特殊经历,辨析了他因得罪春煊而遭参劾被谪戍新疆的原因,及其《壮陶阁书画录》的主要内容及价值。     

简并态锗在大注入下的自发辐射谱模拟

基于费米狄拉克模型模拟了应变、温度以及掺杂对简并态锗的直接带自发辐射谱的影响.随着温度升高,更多的电子被激发到导带中,使得锗自发辐射谱的峰值强度和积分强度随温度的升高而增大.对自发辐射谱峰值强度的m因子进行计算,结果表明张应变可以显著提高锗自发辐射的温度稳定性.在相同应变水平下,由Γ-hh跃迁引起的自发辐射谱峰值强度大于Γ-lh跃迁引起的自发辐射谱峰值强度,但二者的积分强度几乎相等.此外,计算结果还证明了n型掺杂能显著提高锗的自发辐射强度.以上结果对于研究简并态半导体的自发辐射性质有重要的参考意义.