高温氧化多孔硅的电子束辐照效应

通过高温氧化处理得到的多孔硅,其阴极射线发光谱呈现明显的三峰结构。峰强随电子束辐照时间而下降。对光致发光很弱的样品,电子束辐照后光致发光明显地增强。红外透射谱及Raman谱分析表明样品基本上成为SiO_x.进一步分析指出三峰可能来源于SiO_x中的缺陷中心发光。电子束辐照在SiO_x禁带中引进了一些缺陷能级,通过这些能级使得紫外线可激发样品发光,出现光致发光增强的现象。     

Quantum Currents in the coset Space SU(2)/U(1)

We propose a rational quantum deformed nonlocal currentsin the homogeneous space SU(2)k/U(1),and in terms of it and a free boson field a representation for the Drinfeld currents of Yangian double at a general level k=c is obtained.In the classical limit h→0,the quantum nonlocal currents become SU(2)k parafermion,and the realization of Yangian double becomes the parafermion realization of SU(2)k current algebra.     

Optical and Scintillation Properties of NaI(Tl) Crystals

Using absorption spectroscopy and luminescent methods, we have investigated qualitatively dissimilar NaI and NaI(Tl) crystals. It is established that in NaI(Tl) crystals grown under conditions of melt hydrolysis and interaction with the air components, centers of additional luminescence of nonactivation nature are formed that decrease the transparency in the activator-radiation region. Data on the hole nature of these centers are obtained. It is shown that high-temperature annealing can alter the number of centers responsible for the decrease in the transparency of the NaI(Tl) crystals.     

Ti：Al2O3晶体紫外及可见光谱的浓度效应研究

通过对不同浓度的Ｔｉ：Ａｌ２Ｏ３晶体紫外吸收光谱，可见偏振荧光光谱及其激发光谱的研究，发现峰值４２０ｎｍ的宽带可见荧光，室温下较强的σ偏振光在低温（７７Ｋ）下变得比π偏振光弱。在液氮温度下π偏振光谱分裂成３３０ｎｍ，４２０ｎｍ，４６０ｎｍ，５６０ｎｍ等离荧光带。研究认为，这些发光带分别与色心（Ｆ＾＋，Ｆ心）及Ｔｉ＾４＾＋离子的电荷转移跃适有关。并且室温下可见荧光具有的较强的浓度猝灭及现象来源于Ｔｉ     

Nearby Cycles for Local Models of Some Shimura Varieties

Kottwitz conjectured a formula for the (semi-simple) trace of Frobenius on the nearby cycles for the local model of a Shimura variety with Iwahori-type level structure. In this paper, we prove his conjecture in the linear and symplectic cases by adapting an argument of Gaitsgory, who proved an analogous theorem in the equal characteristic case.     

Si衬底上生长的GaAs薄膜中深中心发光的温度效应

测量了Ｓｉ衬底上生长的ＧａＡｓ薄膜中与深中心有关的发光带的变温光谱，研究了０．７８ｅＶ、０．８４ｅＶ和０．９３ｅＶ发光带的峰值位置和发光强度随着温度的变化关系，发现它们的发光强度随温度的变化服从描述非晶半导体中局域态发光的公式。最后讨论了这些发光带的来源。     

Full-field strain measurement using a luminescent coating

In this paper we describe an optical-based technique, called strain sensitive skin (S³), for measuring in-plane strain data on structural members under static load. The technique employs a coating consisting of a luminescent dye and polymer binder that is applied to the surface of a test part via conventional aerosol techniques. Proper illumination stimulates the dye, which in turn emits higher wavelength luminescence. The excitation and emission intensities have different wavelengths; therefore, enabling optical filtering to separate the two signals. The optical strain response is intensity based. A network of randomized microcracks within the binder scatters the waveguided luminescence from the excited dye molecules. The amount of scattered luminescence is related to the changes in the microcrack openings and orientations via mechanical strain. Various calibration tests show the optical strain response to be proportional to the sum of in-plane principal strains. With this new experimental testing tool, full-field high-resolution strain measurements can be acquired. The optical strain response of this new sensor is minimally dependent on viewing and lighting directions, rendering the technique viable to imaging and determining strain fields for three-dimensional complex geometries.     

Mangifera indica leaf-assisted biosynthesis of well-dispersed silver nanoparticles

Natural fluorite crystals containing oxygen impurities are colored electrolytically by using a pointed cathode and a flat anode at various temperatures and voltages. F and F₂ color centers are produced in colored fluorite crystals. O²⁻–V_a⁺, O²⁻–V_a⁺ aggregate, Yb²⁺, Ce³⁺ and Sm²⁺ absorption bands are observed in absorption spectra of uncolored fluorite crystals. O²⁻–V_a⁺, O²⁻–V_a⁺ aggregate, Yb²⁺, Ce³⁺, Sm²⁺, F, M (F₂) absorption bands and group of four absorption bands are observed simultaneously in absorption spectra of colored fluorite crystals. Current−time curve for electrolytic coloration of natural fluorite crystal and its relationship with electrolytic coloration process are given. Production and conversion of color centers are explained.     

民机中央翼舱段适坠性仿真

建立了带中央翼的民机舱段的有限元模型,应用MSC.Dytran分析软件对民机中央翼舱段模型进行坠撞仿真,得到加速度响应和客舱舱体结构变形结果.结果表明,带中央翼舱段发生坠撞后,乘客的生存空间基本没有变化,撞击能量主要靠舱段下部的龙骨梁、框及蒙皮和中央翼壁板的破坏来吸收,地板导轨的峰值加速度比不带中央翼的典型舱段的峰值加速度要大许多.     

Synthesis, Crystal Structure and Luminescent Property of a One-dimensional Europium Citrate Complex

A new compound, [Eu(Hcit)(H2O)2]·H2O]n (1, Hcit3-= C(OH)(COO-)(CH2COO-)2), has been synthesized under hydrothermal reactions of europium oxide, MnCl2·4H2O and citric acid at 120 ℃ for three days. The compound was characterized by single-crystal X-ray diffraction analyses, IR and TGA. Complex 1 crystallizes in monoclinic, space group P21/n with a = 6.179(1), b = 9.688(2), c = 16.990(3) , β = 91.98(3)°, Z = 4, V = 1016.4(3) 3, C6H11EuO10, Mr = 395.11, Dc = 2.582 g/cm3, μ = 6.218 mm-1, F(000) = 760, R = 0.0183 and wR = 0.0411. Single-crystal X-ray analysis reveals that complex 1 displays 1D ladder chains along the a axis, with dinuclear Eu2O2 units serving as "steps" and carboxylate groups as "uprights", which are connected by hydrogen bonds. The solid-state luminescent property of complex 1 was investigated at room temperature. Upon excitation at 394 nm, compound 1 exhibits interesting luminescent properties with several intense bands in the visible region and the most intense and sharp emission being in the red region at 615 nm. The TGA and XRD results prove that complex 1 undergoes facile thermal decomposition to form Eu2O3 at about 870 ℃.