芴-含氮芳杂环共聚物的载流子注入特性

为了改善聚芴的载流子注入特性,采用密度泛函理论B3LYP/6-31G*方法计算比较了芴、芴-联吡啶和芴-菲咯啉低聚物的几何结构、电子结构、最低激发能及重组能等,并外推到相应聚合物.结果发现:联吡啶/菲咯啉含氮芳杂环的缺电子性质能够诱导聚芴的最高占据轨道(HOMO)和最低空轨道(LUMO)能级分别下降0.45/0.47eV和0.32/0.38eV,提高电子注入能力的同时,调控载流子注入平衡;联吡啶单元的引入导致电子和空穴重组能升高(降低聚芴的载流子迁移率),而芴-菲咯啉共聚物显示了与聚芴相似的迁移性能.     

碳载Pt-Ni催化剂对直接甲醇燃料电池阴极氧电还原性能的影响

采用间歇式微波法制备了不同Pt、Ni原子比的碳载Pt-Ni催化剂。XRD结果表明,用这种方法制备的催化剂分散得比较好,具有较小的平均粒径,其中Pt-Ni/C(3∶1)催化剂的粒径最小。在旋转圆盘电极上进行氧的还原测试结果表明,当电解质溶液中没有甲醇和有甲醇存在时,Pt-Ni/C(3∶1)催化剂对氧的催化还原活性都很高,说明Pt-Ni/C(3∶1)催化剂对氧的催化还原受甲醇的影响较小。     

Detection of subsurface defects of fused silica optics by confocal scattering microscopy

<正>A non-destructive technique for subsurface measurements is proposed by combining light scattering method with laser confocal scanning tomography.The depth and distribution of subsurface defect layers are represented in term of scattered light intensity pattern,and three types of fused silica specimens are fabricated by different grinding and polishing processes to verify the validity and effectiveness.By using the direct measurement method with such technique,micron-scale cracks and scratches can be easily distinguished,and the instructional subsurface defect depths of 55,15,and 4μm are given in real time allowing for an in-process observation and detection.     

High-pressure structure and elastic properties of tantalum single crystal:First principles investigation

Since knowledge of the structure and elastic properties of Ta at high pressures is critical for addressing the recent controversies regarding the high-pressure stable phase and elastic properties, we perform a systematical study on the highpressure structure and elastic properties of the cubic Ta by using the first-principles method. Results show that the initial body-centered cubic phase of Ta remains stable even up to 500 GPa and the high-pressure elastic properties are excellently consistent with the available experimental results. Besides, the high-pressure sound velocities of the single- and polycrystals Ta are also calculated based on the elastic constants, and the predications exhibit good agreement with the existing experimental data.     

A time-dependent density functional theory investigation of plasmon resonances of linear Au atomic chains

We report theoretical studies on the plasmon resonances in linear Au atomic chains by using ab initio time-dependent density functional theory. The dipole responses are investigated each as a function of chain length. They converge into a single resonance in the longitudinal mode but split into two transverse modes. As the chain length increases, the longitudinal plasmon mode is redshifted in energy while the transverse modes shift in the opposite direction (blueshifts). In addition, the energy gap between the two transverse modes reduces with chain length increasing. We find that there are unique characteristics, different from those of other metallic chains. These characteristics are crucial to atomic-scale engineering of single-molecule sensing, optical spectroscopy, and so on.     

基于时间控厚离子束溅射技术的宽带减反膜制备

 为了制备满足设计要求的宽角度、宽波段减反膜,利用离子束溅射沉积技术,在时间-功率控厚的模式下,对膜层沉积速率进行了精确修正。在实验中,利用时间-功率控厚的离子束溅射沉积技术,选择HfO₂和SiO₂作为高低折射率组合,在超抛ZF6玻璃基底上制备了宽角度、宽带减反膜,通过对实验后的透过率光谱曲线的数值反演计算,获得膜层厚度修正系数,初步得到了沉积速率随沉积时间变化的规律。利用修正后的沉积参数制备设计的膜系,在0°~30°入射角度下,600~1 200 nm波段的平均透过率达到99%以上。     

金纳米棒的合成及应用研究

金纳米棒具有独特的物理化学性质和良好的生物相容性,在众多的各向异性金纳米结构中引起了研究者的关注.本文综述了金纳米棒的各种制备方法,详尽评价了种子法制备金纳米棒过程的影响因素,介绍了金纳米棒用作药物载体和癌症的光热治疗方面的应用进展,并对金纳米棒的研究前景进行了展望.     

铜包覆多孔硅基材料p-Si@Cu(x)的制备与性能

在球形SiO_2颗粒表面包覆适量的CuO,经还原得到铜包覆的多孔硅复合材料[p-Si@Cu(x)].利用X射线衍射、扫描电子显微镜、透射电子显微镜和比表面积分析等手段对样品的组成、物相结构、微观形貌和孔结构进行分析,并初步研究了材料的循环性能和倍率性能.结果表明,铜包覆量x=0.05时,在100 mA/g电流密度下,样品的首次放电容量为3596.9 mA·h/g,首次充电容量为2590.7 mA·h/g,首次库仑效率为72.03%;在1C倍率下可逆容量为1004.9 mA·h/g,0.1C倍率下循环100周后的可逆容量仍为1706.5mA·h/g,容量保持率为76.1%.     

金属氧化物薄膜光学常数计算物理模型应用研究

采用离子束溅射(IBS)方法制备了HfO₂和Ta₂O₅两种金属氧化物薄膜,通过测量薄膜的椭偏参数,使用非线性最小二乘法反演计算获得薄膜的光学常数。 在拟合过程中,采用L₈(27)正交表设计了8组反演计算实验,在初始选定Cauchy模型后,对HfO₂薄膜拟合影响最大的为表面层模型,对Ta₂O₅薄膜拟合影响最大的为折射率梯度模型。 确定了不同物理模型对拟合函数MSE的影响权重和拟合过程中模型选择的次序,按照确定的模型选择次序拟合,最后加入弱吸收模型反演计算两种薄膜的光学常数,反演计算的MSE相对初始MSE可下降79%和39%,表明拟合过程模型选择物理意义明确,具有广泛的应用价值。 在500 nm处,Ta₂O₅薄膜的折射率梯度大于HfO₂薄膜, 而HfO₂薄膜消光系数大于Ta₂O₅薄膜。 表明Hf金属与Ta金属相比容易氧化形成稳定的氧化物,HfO₂薄膜的吸收要高于Ta₂O₅薄膜。     

Effect of high-temperature ablation on protective coating of ZnS optical windows

While infrared （IR） hard protective film of ZnS optical window is used in high temperature environment, its optical and mechanical stabilities are the premise of the IR optical system. IR hard protective film is deposited on ZnS optical windows by chemical vapor deposition （CVD）, and ablation experiments are done to the maximum temperature the film can endure. The effects of ablation temperature on the optical and mechanical properties of the protective films are investigated by surface profiler, Fourier-transform infrared （FTIR） spectrometry, IR ellipsometer, and Metallographic microscope. It is shown that the optical and mechanical properties of ZnS hard protective film change little before 500 ℃, and film refractive index and optical thickness reduce while ablation temperature surpassing 500 ℃, forming crater-like ablation structure, which leads to the reduction of film combination significantly.