聚合物前驱体衍生SiC纳米棒的光学性质

采用聚硅氮烷前驱体热裂解方法制备SiC纳米棒,并利用SEM、XRD和EDX表征了SiC纳米棒的结构和组成,表明得到的SiC的组分比C：Si接近1：1。用微区Raman和光致发光方法研究了纳米棒的光学性质。观测到SiC的TO模式对应的Raman峰和相邻肩峰。对SiC纳米棒观测到其紫外3．25eV附近强的光致发光峰,我们认为它归结为α型SiC带间的跃迁。通过XRD、Raman和光发射谱,我们推测前驱体热裂解得到的SiC纳米棒是一个混晶,纳米棒的表层是立方晶,而内层主要为a—SiC。     

用于FED和PDP平板显示高压驱动电路的CMOS器件

在Synopsys TCAD软件环境下,结合中国科学院微电子研究所0.8μm标准CMOS工艺条件对于高压CMOS器件进行了工艺和器件模拟。由于考虑到与标准CMOS工艺的兼容性,高压CMOS器件均采用LDMOS结构;根据RESURF技术,对于器件的漂移区进行了优化。器件模拟结果表明,高压NMOS器件源漏击穿电压为220 V;阈值电压和驱动能力分别为0.8 V和1×10-4A/μm。高压PMOS器件源漏击穿电压为-135 V;阈值电压和驱动能力分别为-9.7 V和1.8×10-4A/μm。高压CMOS器件的研制可为进一步研制FED和PDP平板显示高压驱动电路奠定基础。     

多普勒漂移对超音速燃气流光辐射特性计算的影响

分析了超音速射流由于高速相对运动产生多普勒谱线漂移效应对光辐射特性计算的影响。通过采用逐线计算法对不同环境压力、气流温度、气流速度条件下超音速燃气射流在不同的红外光谱区(2.7微米谱带和4.3微米谱带)光辐射谱带积分强度的计算结果比较表明:多普勒漂移效应受环境总压影响最大,压力越大多普勒漂移的影响越小;随着温度升高多普勒漂移效应的影响降低;随着相对速度的增加,多普勒漂移效应的影响多数情况下是增加的。     

The effects of crystal structure on optical absorption/photoluminescence of bis(8-hydroxyquinoline)zinc

In this paper, the transformation processes of two types of bis(8-hydroxyquinoline)zinc: Znq₂ dihydrate and anhydrous (Znq₂)₄ were investigated by X-ray diffraction (XRD), infrared spectra (IR), scanning electron microscope (SEM), differential scanning calorimetry (DSC) and thermogravimetry (TG). The effects of crystal structure on optical properties of bis(8-hydroxyquinoiline)zinc were analyzed. Znq₂ dihydrate can be transformed into anhydrous (Znq₂)₄ during heating under vacuum. Reversal transformation occurs by the interaction between chloroform and (Znq₂)₄. But (Znq₂)₄ was partially transformed into Znq₂ dihydrate by the interaction between ethanol and (Znq₂)₄. The different molecular structure results in different crystal stacking and electronic structure, thereby affect its optical properties.     

Antiproton-Nucleus Interaction and Coulomb Effect at High Energies

The Coulomb effect in high energy antiproton-nucleus elastic and inelastic scattering from ¹²C and ¹⁶O is studied in the framework of Glauber multiple scattering theory for five kinetic energies ranged from 0.23 to 1.83 GeV. A microscopic shell-model nuclear wave functions, Woods-Saxon single-particle wave functions, and experimental pN amplitudes are used in the calculations. The results show that the Coulomb effect is of paramount importance for filling up the dips of differential cross sections. We claim that the present result for inelastic scattering of antiproton-¹²C is sufficiently reliable to be a guide for measurements in the very near future. We also believe that antiproton nucleus elastic and inelastic scattering may produce new information on both the nuclear structure and the antinucleon-nucleon interaction, in particular the p-neutron interaction.     

Influence of angular momentum in axially symmetric potentials with octupole deformation

The chaotic classical single-particle motion in an oblate octupole deformed potential with a non-zero z-component of angular momentum Lz is investigated. The stability analysis of the trajectories shows that with increasing rotation of the system, the unstable negative curvature regions of the effective potential surface decrease, which converts the chaotic motion of the system into a regular one.     

水溶液中Cr^3＋的火焰原子吸收光谱法测试条件的优化

为优化火焰原子吸收光谱法测定水溶液中的Cr^3＋的测试条件,分别采用单因素简单比较法、正交实验设计极差分析及正交实验回归方法考察了光谱通带n,空心阴极灯电流I,燃烧器高度h以及乙炔/空气流量比P对于仪器灵敏度的影响。结果表明单因素简单比较法获得的实验条件最优。乙炔/空气流量比P对火焰原子吸收仪器灵敏度影响最大、其次是光谱通带n,燃烧器高度h和灯电流I的影响很小。测定水溶液中的Cr^3＋时仪器灵敏度最佳的实验条件为：乙炔/空气流量比P=0.4;光谱通带n=0.2nm;灯电流I=5mA;燃烧器高度h=5cm。     

Determination of the in-plane anisotropy field in hexagonal systems via rotational magnetization: Theoretical model and Monte Carlo simulations

The magnetic anisotropy field in thin films with in-plane uniaxial anisotropy can be deduced from the VSM magnetization curves measured in magnetic fields of constant magnitudes. This offers a new possibility of applying rotational magnetization curves to determine the first- and second-order anisotropy constant in these films. In this paper we report a theoretical derivation of rotational magnetization curve in hexagonal crystal system with easy-plane anisotropy based on the principle of the minimum total energy. This model is applied to calculate and analyze the rotational magnetization process for magnetic spherical particles with hexagonal easy-plane anisotropy when rotating the external magnetic field in the basal plane. The theoretical calculations are consistent with Monte Carlo simulation results. It is found that to well reproduce experimental curves, the effect of coercive force on the magnetization reversal process should be fully considered when the intensity of the external field is much weaker than that of the anisotropy field. Our research proves that the rotational magnetization curve from VSM measurement provides an effective access to analyze the in-plane anisotropy constant K ₃ in hexagonal compounds, and the suitable experimental condition to measure K ₃ is met when the ratio of the magnitude of the external field to that of the anisotropy field is around 0.2. Supported by the National Natural Science Foundation of China (Grant Nos. 90505007 and 10774061) Recommended by LI FaShen     

嵌段共聚物溶致液晶相中水的2H-NMR动力学分析

采用D₂O 的²H-NMR线型和弛豫分析了PEO-PPO-PEO/D₂O/对二甲苯体系的层状和六角液晶相的动力学行为. 通过实验测得了两个不同体系的自旋 晶格弛豫时间T₁、自旋-自旋弛豫时间T₂和²H-NMR 谱. ²H-NMR 谱均为具有四极劈裂的粉末谱线型，且在谱图的中心，β_LD=54.7°时存在一个倒峰. 倒峰的出现直接表明引起体系中弛豫的主要动力学过程处于极窄化区域. 采用NMR弛豫模型，通过调节动力学参数，使理论模拟的²H-NMR谱、弛豫时间、倒峰的大小与实验的对应量相吻合，求得了体系的动力学参数.     

Electronic structure and magnetic properties of metastable SmCo_7 compound

1 Introduction The rare-earth transition-metal intermetallic compounds have been widely investi-gated for many years, among them the Sm-Co series compounds with 1:5 and 2:17 crys-tal structures. These compounds have been used as sintered and bonded permanent magnets since the 1960s[1,2]. Interest recently has been focused on the TbCu7-type struc-ture Sm-Co intermetallic compounds with a strong uniaxial magnetocrytalline anisot-ropy and a low temperature coefficient (β = ?0.11%)[3―6] due t…