182Os 核yrast带相继SU(3)–U(5)–SU(3)结构相变势能曲面的一种可能理解

基于联合实施微观相互作用玻色子模型的最大F旋方案 (sdIBM-F_max)与γ射线能量-自旋曲线 (γ-ray energy over spin curves, E-GOS)方案, 成功描述了¹⁸²Os核yrast带相继的SU(3)–U(5)–SU(3)结构相变, 由于缺少直观解释而显得抽象. 本文借助微观sdIBM-F_max的微观参数与Bohr哈密顿量的势能曲面方程之间存在的泛函关系, 几何地给出了对这种相继相变途径的另外一种可能理解; 并阐述了在完全变形核的高角动量态中, 由于量子效应在高激发态与低激发态之间生成高简并的临界区, 提供了γ振动能量会变得低于转动能量的一个可能途径, 从而实现了SU(3)–U(5)的相变. 关键词： yrast带结构演化 势能曲面 相变临界区 182Os核')" href="#">¹⁸²Os核     

薄膜硅的变隙问题及隙态分布

用电子束蒸发的方法制备可变光学带隙薄膜硅材料, 给出了研究结果. 介绍了一种做透过率曲线切线确定薄膜光学带隙的简易方法, 给出了制备工艺和条件, 以及各种材料的隙态分布图. 实验发现, 材料的光学带隙宽度不但与量子尺度效应有关, 而且与缺陷形成的势垒高度和宽度以及有序短程(原子串)长度有关; 给出了常规硅材料的光学带隙与原子串长度的关系. 计算表明, 随着原子串长度的加大, 势阱中的电子液面升高, 载流子受缺陷势垒的散射减弱; 在原子串长度较低的情况下, 电子液面不总是随着原子串长度升高, 而是有较大的涨落, 形成锯齿状波动.计算还发现, 在势垒宽度与原子串长度之比不变的情况下, 电子液面还与势垒高度有关. 关键词： 薄膜硅 可变光学带隙 隙态分布 电子液面涨落     

苯硫酚吸附在新型Ag-Au合金纳米粒子上的表面增强拉曼光谱研究

以柠檬酸钠同时还原制备的Ag-Au合金纳米粒子为种子,用盐酸羟胺进一步使其生长得到粒径为40～60 nm的新型Ag-Au合金纳米粒子,采用UV-Vis光谱和TEM对纳米种子和再生长后的纳米粒子分别进行表征。两种粒子的UV-Vis光谱均只观察到一个等离子体共振峰,其频率随金的摩尔分数(x_Au)增加而红移,且TEM图像表明这两种粒子的颜色均一,因此判断这两种粒子均为合金结构。以苯硫酚为探针分子,研究了该新型合金纳米粒子的表面增强拉曼光谱(SERS),结果表明吸附了苯硫酚的合金纳米粒子的紫外最大吸收峰红移,并在近红外区出现聚集体的吸收峰。在632.8 nm波长激发下,由于表面等离子体共振效应Au上的SERS信号最强,而合金纳米粒子上的SERS信号随x_Au增大而增强。     

^95Zr核的高自旋态研究

利用102MeV的^28Si束流，通过^60Ni(^28Si，2pn)熔合蒸发反应布居了^85Zr核的高自旋态，测量了γ-γ符合及DCO比值，建立了一个有43条能级，75条γ跃迁的能级纲图，新增加了36条γ跃迁，25条能级。将能级自旋推高到（49/2^ ），首次观察到了转边带的第二回弯。并确认了一条建立在17/2^-负字称带上的磁转动带。     

超形变奇—奇核^194RI中的双堵塞效应

采用处理含有对力的推转壳模型的粒子数字恒方法研究了A－190区奇奇核194TI中6条超形变带，计算结果与实验符合得非常好，根据我们的PNC计算结果，分别指定了194TI的6条超形变带的组态，详细分析了质子和中子的堵塞效应对转动惯形的影响，转动惯量随转动频率的变化主要来源于高N闯入壳（对中子N＝7，对质子N＝6）的贡献，而其他大壳对转动惯量的贡献基本上不随转动频率变化。     

Systematic Study on the Superdeformed Bands of Double Odd Nuclei in A～130 Region

Properties of the superdeformed bands of odd-odd nuclei in A～130 mass region are investigated systematically within the supersymmetry scheme including many-body interactions and a perturbation possessing the SO(5) (or SU(5)) symmetry on the rotational symmetry. The obtained γ-ray energies, the dynamical moments of inertia, and energy differences △Eγ - △Eγ^ref agree wlth experimental data. It shows that this approach is quite powerful in describing odd-odd nuclei in 130 mass region.     

Experimental and Theoretical Evidence for the Existence of Broad Forbidden Gaps in the Three—Component Composite

The influence of localized resonance on the properties of band-gaps of the two-dimensional periodic composite are analysed numerically and experimentally by comparing the two-component phononic crystal with the three-component one. The three-component composite which exhibits localized resonance in the elastically soft coating ring is composed of a square array of coated cylinders embedded in an epoxy resin. The coated cylinders consist of a steel inner core and a rubber coating, which has much smaller wave velocity and mass density than the matrixand tile inner material. Tile measured transmission power of tile three-component composite drops to the noise level in a broad ultrasonic frequency interval in contrast to the binary composite, which is in good agreement with the calculation using the finite element method.     

Giant Positive Magnetoresistance in Grain-Oriented CxCo1-x Alloys

The grain-oriented CxGo1-z (x = 0.9, 0.5) samples were fabricated by the hot.pressing method. The microstruc-ture was observed by an x-ray diffractometer and a scanning electron microscope. The resistance against the applied magnetic field was measured by a standard four-polnt probe method at different temperatures. The magnetoresistance and the magnetization ratio were studied as a function of magnetic field in the range of -1800 kA/m-1800 kA /m at different temperatures from 50 K to 300 K. The magnetoresistance of grain-oriented GxGo1-x is positive. The maximum positive MR of 98% at 50 K and 34% at 300 K was obtained under 1800 kA/m magnetic field in the C0.9Go0.1 sample.     

Magnetic Microstructures of PryFe90－yB10 （y = 8－11.76） Nanocrystalline Ribbons Using Magnetic Force Microscopy ＊

Magnetic microstructure of melt-spun PryFe90-yB10 (y = 8, 8.5, 9, 9.5, 10 and 11.76) nanocrystalline ribbons in an as-grown state has been studied using a magnetic force microscope. The magnetic domains are characterized by dark areas adjacent to bright areas in a sub-micron scale and in random distribution. By comparing with the size of the micro-crystals measured from the TEM image, the exchange coupling effect was confirmed to exist inall the ribbons. Using the roughness analysis, the variation of the root mean-square values of the phase shifts obtained from the magnetic force images versus the content y of Pr were measured, which is very consistent with the curve of the residual induction Bγ versus the content y.     

钯合金吸氢容量的理论预计

吸氢容量是一定温度下，钯合金吸氢至饱和时，生成的金属氢化物中氢的浓度。它是钯合金在实际应用中的重要数据之一。赵爽等人进行了LaNi5-xMx系列吸氢容量的理论预测，计算结果的平均误差为1．8％。本工作利用逐步回归法寻找影响钯合金吸氢容量的主要原子参量，建立了预计钯合金吸氢容量的半经验模型，计算结果与文献值基本吻合。