离子注入法形成的LiTaO3平板光波导的特性分析

用能量为２．８ＭｅＶ、剂量为１．４×１０１６ｉｏｎ／ｃｍ２的Ｈｅ＋在室温（３００Ｋ）下注入到晶体材料ＬｉＴａＯ３中，形成了离子注入平板光波导。用棱镜耦合法观察和测量了ＬｉＴａＯ３波导导模的分布，并对退火前后的ＬｉＴａＯ３波导的折射率分布进行了计算和比较。利用背散射／沟道技术分析了由于Ｈｅ＋的注入而引起的波导表面的损伤。     

Polymerization of Silicon-Doped Heterofullerenes： an Ab Initio Study

We perform the calculations on geometric and electronic structures of Si-doped heterofullerene C5oSi10 and its derivatives, a C40Si20-C40Si20 dimer and a C40Si20-based nanowire by using density-functional theory, The optimized configuration of the C40Si20-based nanowire exhibits a regular dumbbell-shaped chain nanostructure. The electronic structure calculations indicate that the HOMO-LUMO gaps of the heterofullerene-based materials can be greatly modified by substitutionally doping with Si atoms and show a decreasing trend with increase cluster size. Unlike the band structures of the conventional wide band gap silicon carbide nanomaterials, the C40Si20- based nanowire has a very narrow direct band gap of 0.087eV.     

基于二维旋转屏的体三维显示系统像素属性分析

介绍了利用视觉暂留效应、高速扫描处于快速旋转中的二维显示屏,从而在三维实空间内再现图像的体三维显示系统.体像素是与三维图像空间内的点对应的图像信息的表述单元,其形状、位置、数目及密度分布等属性,直接影响图像的再现质量和系统的整体性能.对决定体像素属性的屏幕像素尺寸、排列规律及刷新率间的匹配关系进行了建模和量化分析,并从实验上说明了体像素的空间密度分布不均匀时,会导致在显示空间不同位置的同一原始模型有不同的再现效果.     

二值干涉型计算全息图

本文研究二值干涉型计算全息图,这种全息图最适于综合位相型波前,因此本文的讨论也只限于位相型波前的情况,对物光和参考光的选择以及全息图的抽样进行了分析,并得出相应的结论。     

ION-BEAM-INDUCED SOLID PHASE CRYSTALLIZATION OF MeV Si+-IMPLANTED Si(100)

The behavior of ion-beam-induced crystallization of a buried amorphous layer created by means of MeV Si⁺ irradiation at 300℃ in Si(100) was studied by Rutherford backscattering and channeling technique. Sohd phase epitaxial crystallizations occurred from both the front and the back amorphous-crystalline(a/c) interfaces with the growth thickness being increased linearly with increasing dose of the annealing ion beam, Nuclear energy deposition was proved to play a dominant role in the process of ion-beam-induced crystallization. The high density of electronic excitation, which could enhance defect production near or at the a/c interface, may thus enhance the nuclearly normalized growth rate of ion-beam-induced crystallization at the front a/c interface.     

Ag/MgO串联协同催化降解偶氮染料

以纳米氧化镁为载体,采用浸渍法制备一系列过渡金属负载型催化剂。测试其对染料的降解性能后筛选出了效果最优的催化剂Ag/MgO,并采用X射线衍射(XRD)、X射线光电子能谱(XPS)、透射电子显微镜(TEM)、扩展X射线吸收精细结构谱(EXAFS)以及X射线吸收近边结构(XANES)等表征方法对该催化材料的结构特征、微观形貌进行分析。通过表征分析发现Ag是以纳米簇的形式均匀地分散在MgO表面,Ag和Mg之间形成了双金属位点,且催化剂中Ag的电子密度较高,从而具有较高的催化活性。在甲醛溶液中,在室温、无需光热等条件下即可高效降解偶氮染料AR1。该反应体系中影响降解效果的因素主要是温度和甲醛浓度,温度升高,降解效率增大,但甲醛浓度有最优值(1 mol·L^-1)。通过自由基捕获实验测得反应中有2种自由基在发挥作用,即具有还原性的氢自由基和具有氧化性的超氧自由基,它们的协同作用可以将染料分子中的显色基团(—N=N—)轻易地破坏,这种"还原-氧化"的协同作用机制提高了反应效率。此外,醛类也是常见污染物之一,将其作为助剂的同时达到了"以污治污"的效果。     

一种新型氧离子导体：La3GaMo2O12

A new oxide ion conductor,La_3GaMo_2O_(12),with a bulk conductivity of 2.7×10~(-2)S·cm~(-1) at 800 ℃ in air at-mosphere was prepared by the traditional solid-state reaction.The room temperature X-ray diffraction data could beindexed on a monoclinic cell with lattice parameters of a=0.5602(2) nm,b=0.3224(1) nm,c=1.5741(1) nm,β=102.555(0)°,V= 0.2775(2) nm~3 and space group Pc(7).Ac impedance measurements in various atmospheres furthersupport that it is an oxide ion conductor.This material was stable in various atmospheres with oxygen partial pres-sure p(O_2)ranging from 1.0×10~5 to 1.0×10~(-7) Pa at 800 ℃.A reversible polymorphic phase transition occurred atelevated temperatures as confirmed by the differential thermal analysis and dilatometric measurement.     

混沌系统的自适应延迟控制

本文结合Ｐｙｒａｇａｓ的延迟反旬控制思想，提出了镇定混沌吸引子中嵌入的不稳定周期轨道的自适应延迟控制法。避免了常规自适应控制方法需要设计参圪模型或确定目标状态的麻烦，字种自适应延迟控制方法，控制器简单，实时性好，数值仿真结果验证了这种方法的有效性。     

生物厚靶的He+离子透射能谱

测量了500keV—1MeV的He⁺离子穿过50—90μm厚度的玉米种皮、葡萄果皮和西红柿果皮的透射能谱．结果表明这些生物厚靶是不均匀的,存在着类似于“沟道”的开放通道,沿着这些通道入射离子可以容易地透过靶材料．虽然大多数离子停留在靶中,但一部分透射离子只损失很少的能量．透射能谱显示出一种纯粹的电子阻止特征．30μm厚度样品的透射电子显微镜图谱(TEM)显示150keV的电子可以穿过这些样品得到很清晰的图象．β-1,4葡聚糖是生物种皮或果皮细胞壁的重要的组成部分,计算了该分子链的电子