Silicon-phthalocyanine bonding with SiO2 matrix and its strong optical limiting effects

Silicon-phthalocyanine (SiPc) is chemically bonded to 3-aminopropitriethoxysilane (NH₂(CH₂)₃Si(OC₂H₅)₃, KH550) by the nucleophilic substituted reaction between the active chlorine of silicon dichlorine phthalocyanine (SiPcCl₂) and amino-group of KH550. The reacted product is hybridized with 3-glycidoxypropitrimethoxysilane (CH₂OCHCH₂O(CH₂)₃Si(OCH₃)₃, KH560) with sol-gel processing to form sol-gel inorganic material with good physical-chemical and optical properties. Due to tethering SiPc to the network, the aggregation of SiPc is effectively prevented in sol-gel derived matrix, and the doping concentration of SiPc in the form of monomer in the matrix is greatly enhanced. The cross-linkage of SiPcCl₂ and KH550 is estimated and confirmed with FT-IR spectra. The optical limiting effects (OLE) of the gel with different content of SiPc are investigated with a frequency double Q-switched Nd₃₊:YAG laser of 8 nsec. pulse.     

C60氮丙啶衍生物的表征及其光限幅效应

研究了叠氮乙酰胺与C60反应,其反应机理为经过一个三唑啉中间体结构形成最终产物;分析表征了C60氮乙酰胺,通过量化计算确定了氮丙啶闭环结构为热力学稳定结构;应用倍频Nd:YAG脉冲激光测试了它的光限幅性能,确定其光限幅机制为反饱和吸收,长波长(707 nm)激光的限幅效果要优于C60,表明C60衍生物是一种非常有希望的激光限幅材料.     

连续激光照射下In_2O_3纳米微粒的光学限幅特性

随着现代科学技术的飞速发展 ,高灵敏快速响应探测器产生广泛应用 ,为了避免强光照射对这些精密仪器的损伤 ,光限幅器的需求也日渐迫切。本文用Z -扫描技术测量了表面修饰In2 O3 纳米微粒的有效非线性系数n2 和光学限幅特性曲线 ,发现在连续激光照射下In2 O3 纳米微粒呈现出较好的光限幅特性 ,光限幅阈值明显低于相应的体相材料。在不同入射功率作用下 ,观察到了奇异吸收特性     

Synthesis of N-acetamide C60 nitride and its performance of optical limiting

N-acetamide C60 nitride (N-acetamide-1,2-dihydro-1,2-aza-fullerene[60]) has been synthesized by the reaction of C60 and azidoacetamide and initially characterized. Its mechanism was that the objective product is formed through intermediate triazoline. The computational study shows that N-nitride structure is thermodynamically more stable by using the semi-empirical AM1 SCF-MO method. The properties of optical limiting were tested by using double frequency Nd∶YAG pulse laser system and showed that the optical limiting mechanism is reverse saturation absorption. A wavelength of 532 nm, compared with optical limiting for ns pulse, this new material has good optical limiting character for ps pulse. At wavelength of 707 nm, the capacity of optical limiting of the derivative is prior to C60.     

Synthesis of N-acetamide C60 nitride and its performance of optical limiting

N-acetamide C₆₀ nitride (N-acetamide-1,2-dihydro-1,2-aza-fullerene [60]) has been synthesized by the reaction of C₆₀ and azidoacetamide and initially characterized. Its mechanism was that the objective product is formed through intermediate triazoline. The computational study shows that N-nitride structure is thermodynamically more stable by using the semi-empirical AM1 SCF-MO method. The properties of optical limiting were tested by using double frequency Nd: YAG pulse laser system and showed that the optical limiting mechanism is reverse saturation absorption. At wavelength of 532 nm, compared with optical limiting for ns pulse, this new material has good optical limiting character for ps pulse. At wavelength of 707 nm, the capacity of optical limiting of the derivative is prior to C₆₀.     

Electron structures and non-linear optical properties oftertbutyl-nitro-phthalocyanines

The electron structures and the non-linear optical properties of phthalocyanines and asymmetrically substituted phthalocyanines are studied with the AM1 method. The results show that thetertbutyl-nitro-phthalocyanines have much higher second order non-linear optical coefficients.     

Low energy H+ effects on the photovoltaic and optical properties of polycrystalline silicon solar cells

Low energy hydrogen ion was used to passivate the electrically active defects existing in grains and grain boundaries of polycrystalline silicon solar cells. Short-circuit current of H⁺ implanted cells remarkably increased before and after preparing TiO₂AR (antireflective) coating. The measurements (at λ=6328 Å) of the optical properties of H⁺ implanted silicon samples show that: the value of absorption coefficient reached the level of a-Si; refractive indexn and ref?ectivityR significantly decreased; the optical band gap increased from 1.1 eV to 1.3 eV. The results indicate that Si-H bonds have been formed after H⁺ implantation. The calculation shows that the optical thickness cycle of TiO₂ AR coating will reduce correspondingly in order to obtain the optimum optical match between AR coating and implanted silicon since refractive index decreases after H⁺ implantation.     

修正协方差阵的投资组合方案及其稳定性

分析了最优化投资组合不稳定的原因,在此基础上,推广了由前人提出的一个新方法,即根据随机矩阵定理(RMT)对样本协差阵进行变化以得到一个更好的投资方案.首先对该方法中未证明的部分给出了更充分的实证理由,并运用这种思想,结合中国证券市场的实际数据,来模拟“真实的投资”.而这种方法得到的投资方案,较之传统方法有较好的收益率和方差,且可被前人对风险预测的分析方法所解释.     

Ag/SiO2介孔组装体系的结构与光吸收特性

纳米颗粒介孔组装体系的光学特性是纳米材料领域的重要研究内容,采用浸泡-氢还原的方法制得Ag/SiO2介孔组装体系,通过透射电子显微镜(TEM)对样品进行表征,使用分光光度计(Cary 5E UV-Vir)对在不同还原温度下制得的样品进行光吸收测量.TEM结果证明银颗粒近似为球形,呈高度弥散且均匀分布于介孔之中,颗粒直径约为5 nm.光吸收测量结果发现,在还原性气氛H2中制备的样品表现出Ag纳米颗粒的吸收,即由自由电子共振引起的表面等离子体共振(SPR)吸收峰,且随着处理温度的升高,吸收边红移.     

表面图案化PNIPAM/SiO2复合微球的制备和表征

采用反相悬浮聚合法合成了聚N-异丙基丙烯酰胺（PNIPAM）高分子微凝胶,以PNIPAM为微反应器,利用四乙氧基正硅烷在氨水介质中的溶胶-凝胶反应,制得了具有表面图案化的核-壳型微米级PNIPAM/SiO2复合微球.并利用扫描电镜、红外光谱仪和热重分析等手段对复合微球进行了形貌和组分表征.     

Ultrafast polarization optical switch constructed from one-dimensional photonic crystal and its performance analysis

All-optical switch with the ultrafast optical switching rate is a key device in the next generation optical network. In this article, we propose a polarization switch with ps switching time, which is constructed from one-dimensional resonant photonic crystal （1D RPC）. The model of switch operating at 1.5 μm is established based on the optical stark effect （OSE）. We calculate the performance indices of the switch and the influences of errors of periods and refractive index on the performance characteristics.     

小角度测量的光学方法及应用

光学测角法是高精度动态角度测量的一种有效的解决途径．对目前发展较快的几种小角度测量的光学方法——圆光栅测角法、光学内反射小角度测量法和激光干涉测角法进行了介绍．对光学测角法在舰船甲板变形测量中的应用进行了详细的阐述．     

低发射率SiO2/Al2 O3纳米复合粉体的制备和红外隐身性能

采用溶胶-凝胶法制备非晶态和结晶态两种相结构的SiO2/Al2 O3纳米复合粉体,通过X射线衍射、透射电子显微镜等手段对纳米复合粉体结构和形貌进行表征,并利用傅里叶变换红外光谱仪研究纳米复合粉体的红外隐身性能.结果表明：两种相结构的SiO2/Al2 O3纳米复合粉体均呈不规则颗粒状,其中结晶态SiO2/Al2 O3纳米复合粉体的平均晶粒尺寸约为18 nm;结晶态SiO2/Al2 O3纳米复合粉体在2.5~25μm波长范围内的红外发射率均低于非晶态复合粉体,3~5μm内发射率平均值为45.65%,8~14μm内发射率平均值为46.19%,是一种低发射率的红外隐身复合纳米材料.     

水泥基复合材料的孔结构与强度相关性研究

采用X射线小角散射技术和压汞法测定了水泥基复合材料的孔结构，结合孔结构模型试验和有限元计算分析，研究了水泥基复合材料的孔结构与强度的相关性。结果表明，孔隙率、孔分布、孔形状和孔界面分形维数与强度之间存在一定的相关性，孔结构对抗压强度的影响与对抗折强度的影响有所不同。     

Preparation and kinetic analysis of Li4SiO4 sorbents with different silicon sources for high temperature CO2 capture

Using diatomite and analytical pure SiO2 as silicon sources,Li4SiO4 sorbents for high temperature CO2 capture were prepared through solid-state reaction method.Phase composition was analyzed by X-ray diffraction,and the CO2 absorption capacity and absorptoin-desorption performance were studied by the simultaneous thermal thermogravimetric analyzer(TG-DSC).The results showed that silicon source had an important influence on CO2 absorption properties.The kinetic parameters for the chemisorption and diffusion processes were obtained by the isothermal study for different silicon sources.The results showed that the activation energies for these two processes were estimated to be 105.427 and 35.928 kJ/mol for the sample with analytical pure SiO2(AS).While for the sample with diatomite(DS),the activation energies for these two processes were estimated to be 78.500 and 20.439 kJ/mol,respectively.     

稀土掺杂纳米TiO2光催化材料的制备和性能

采用溶胶-凝胶法制备稀土(La,Eu,Ce)掺杂纳米TiO2光催化材料,通过XRD、TEM等手段对其进行表征.以甲基橙为模型污染物,测试其光催化活性.研究稀土掺杂量、烧结温度和烧结时间对TiO2光催化活性的影响.结果表明,各因素对材料的催化活性均存在一个最佳值;除500 ℃烧结的Eu-TiO2样品由纯锐钛矿相组成外,其余样品均由锐钛矿和金红石混晶组成,而未见稀土氧化物;稀土掺杂可显著提高TiO2的光催化活性,其中Eu-TiO2对甲基橙的光降解率可达91.05%.     

沉淀二氧化硅载银抗菌剂的制备及其抗菌性能

以沉淀二氧化硅为载体，吸附硝酸银后，在500℃下灼烧，制备了具有抗菌功能的线银沉淀二氧化硅抗菌剂，并检验了其抗菌性能；还对抗菌剂的抗菌机理进行了初步探讨。测试结果表明，沉淀二氧化硅的载银量在7％以上时，所制备的抗菌剂对绿脓杆菌、大肠杆菌和枯草杆菌的杀菌率达到100％，具有优异的抗菌性能，可用于抗菌塑料、抗菌食品包装、抗菌卫生纸和抗菌纺织制品等领域。     

Ge2Sb2Te5薄膜相变行为及其对光存储特性影响

采用射频磁控溅射方法,在石英玻璃基片上制备了Ge2Sb2Te5相变薄膜.X射线衍射分析表明:室温沉积的薄膜为非晶态;170℃真空退火后,薄膜转变为晶粒尺度约为17 nm的面心立方结构;250 ℃退火导致晶粒尺度约为40 nm的密排六方相出现.研究了室温至450℃下薄膜相变的热力学性能.差热分析显示:薄膜的非晶相向fcc相转变的相变活化能为(2.03±0.15)eV;fcc相向hex相转变的相变活化能为(1.58±0.24)eV.薄膜反射率测量表明:面心相与非晶相的反射率对比度随着波长从400 nm增加到1 000 nm在15%～30%变化,六方相与非晶相的反射率对比度在30%～40%.不同脉冲宽度的激光对非晶态薄膜的烧蚀结果显示:激光的能量密度对薄膜的记录效果有显著影响,在5 mW、50 ns的脉冲激光作用下,Ge2Sb2Te5薄膜具有最好的光存储效果.     

嘧啶环二炔氮桥C60衍生物的合成及非线性光学性质

合成了嘧啶环二炔氮桥C₆₀衍生物C₆₀NPD ,研究了在532nm、脉宽 8ns条件下的非线性光学特性。通过Z-扫描实验发现C₆₀NPD有很强的非线性吸收和非线性折射,并获得了三阶非线性光学系数χ⁽³⁾ 。同时也研究了光限幅特性，实验结果表明C₆₀NPD有较低的光限幅箝位值。     

多变量矩阵方程的对称最小二乘解及其最佳逼近

鉴于用矩阵分解的方法求解多变量矩阵方程的复杂性,本文提出了一类迭代算法用于求解多变量矩阵方程的对称最小二乘解并证明了其收敛性,而且在选取特殊的初始对称矩阵组时,能得到它的极小范数解组.另外,给定任意矩阵组,利用此方法可得到它的最佳逼近对称解组.数值试验表明,这种方法相当有效.