利用光电离技术研究奇宇称的Sm原子光谱

采用一台频率可扫描的染料激光器将Sm原子从4f66s2 7FJ(J=1,2)态分别激发到具有不同电子组态的若干原子态上,然后利用光电离技术对处于上述状态的Sm原子进行高灵敏探测.通过波长固定在355nm的紫外激光器,我们对一系列具有4f66s6p或者4f55d6s2电子组态的原子状态进行了精密的光谱测量.本实验研究不但确定了这些态的能级位置,还给出了它们的相对光谱强度.通过理论方法对光谱数据详细的分析,我们不但确认了文献中Sm原子的部分奇字称能级的位置和光谱标识,还同时给出了许多新的跃迁及其光谱特性.     

Ba原子6pnd(J=1, 3)自电离光谱的实验研究

采用三台可调谐激光实施孤立实激发,分三步将处于基态的Ba原子激发到6p_1/2nd(J=1,3)和6p_3/2nd(J=1,3)自电离态上,获得了分别从6snd¹D₂(n=7—15)和6snd³D₂(n=7—12) 激发而得到的6p_1/2nd(J=1,3)和6p_3/2nd (J=1,3)自电离光谱,重点对主量子数n较低的自电离态进行了实验研究. 通过光谱的线形拟合得到了上述能级的位置和宽度等数据,进而获得了量子亏损和约化宽度等信息. 通过对不同系列的自电离光谱的分析和比较,详细讨论了这些自电离态的光谱特征及其复杂光谱结构的成因. 关键词： 孤立实激发 组态相互作用 自电离态     

低温分子束外延生长的GaMnAs反射光谱的低能振荡现象

通过傅里叶变换红外光谱和光调制反射光谱技术测量了不同Mn含量的低温分子束外延生长在GaAs衬底上的GaMnAs样品的反射光谱.在低于Ga(Mn)As带边的红外反射光谱和光调制反射光谱上观测到低能振荡现象.通过分析振荡产生的原因并使用双层界面反射模型拟合了红外反射光谱的低能振荡过程,拟合结果与实验相符.研究表明,反射光谱的低能振荡是由于GaMnAs中空穴浓度的变化导致GaMnAs中的折射率发生变化,GaMnAs与衬底GaAs之间的折射率差导致了不同Mn含量的GaMnAs材料的反射谱的低能振荡现象.测量了不同 关键词： GaMnAs 反射光谱 空穴浓度 折射率     

衬底对Cu(In,Ga)Se2薄膜织构的影响

分别在苏打石灰玻璃、Mo箔、无择优取向的Mo薄膜以及(110)择优取向的Mo薄膜四种不同衬底上,采用共蒸发工艺沉积约2μm厚的Cu(In,Ga)Se2薄膜,用X射线衍射仪测量薄膜的织构,研究衬底对Cu(In,Ga)Se2薄膜织构的影响.在以上四种衬底上沉积的Cu(In,Ga)Se2薄膜的(112)衍射峰强度依次逐渐减弱,(220/204)衍射峰从无到有且强度逐渐增强.在苏打石灰玻璃和Mo箔衬底上的Cu(In,Ga)Se2薄膜具有明显的(112)择优生长,而在(110)取向的Mo薄膜衬底上,Cu(In,Ga)Se2薄膜的织构为(220/204)取向.研究结果表明,只有(110)择优取向的Mo薄膜衬底对Cu(In,Ga)Se2薄膜(220/204)织构的形成有重要影响.     

Effect of Crucibles on Qualities of Self-Seeded Aluminium Nitride Crystals Grown by Sublimation

Self-seeded aluminium nitride （AlN） crystals are grown in tungsten and hot pressed boron nitride （HPBN） crucibles with different shapes by a sublimation method. The qualities of the AlN crystals are characterized by high-resolution transmission electronic microscopy （HRTEM）, scanning electron microscopy （SEM） and Micro-Rarnan spectroscopy. The results indicate that the better quality crystals can be collected in conical tungsten crucible.     

Analogy between soap film and gas dynamics. II. Experiments on one-dimensional motion of shock waves in soap films

This paper presents an experimental investigation of one-dimensional moving shock waves in vertical soap films. The shock waves were generated by bursting the films with a perforating spark. Images of propagating shock waves and small disturbances were recorded using a fast line scan CCD camera. An aureole and a shock wave preceding the rim of the expanding hole were clearly observed. These images are similar to the x-t diagrams in gas dynamics and give the velocities of shock and sound waves. The moving shock waves cause jumps in thickness. The variations of the induced Mach number, M₂ and the ratio of film thickness across the shock wave, δ ₂/δ ₁, are plotted versus the shock Mach number, M _s. Both results suggest that soap films are analogous to compressible gases with a specific heat ratio of γ≅1.0. Published online: 15 October 2002     

抗癌药物的电化学研究Ⅰ.一种Fe(Ⅲ)Schiff碱配合物的基本电化学性质及其与DNA的相互作用

研究了一种自合成的Schiff碱配合物的电化学行为及其与氧和DNA的相互作用.发现此种Schiff碱配合物能与氧发生相互作用而具有吸氧功能,并对氧的电还原有催化作用,同时还发现dsDNA能与此种Schiff碱配合物发生较强的相互作用,特别是Fe(Ⅱ)Schiff碱配合物更易与dsDNA结合.     

Properties of GaN on different polarity buffer layers by hydride vapour phase epitaxy

This paper reports on N-, mixed-, and Ga-polarity buffer layers are grown by molecular beam epitaxy (MBE) on sapphire (0001) substrates, with the GaN thicker films grown on the buffer layer with different polarity by hydride vapour epitaxy technique (HVPE). The surface morphology, structural and optical properties of these HVPE-GaN epilayers are characterized by wet chemical etching, scanning electron microscope, x-ray diffraction, and photoluminescence spectrum respectively. It finds that the N-polarity film is unstable against the higher growth temperature and wet chemical etching, while that of GaN polarity one is stable. The results indicate that the crystalline quality of HVPE-GaN epilayers depends on the polarity of buffer layers.     

Isovector Scalar Field Effects in Asymmetric Nuclear Matter

Density-dependent parametrization models of the nucleon-meson coupfing constants, including the isovector scalar δ-field, are applied to asymmetric nuclear matter. The nuclear equation of state （EOS） and the neutron star properties are studied in a relativistic Lagrangian density, using the relativistic mean field （RMF） hadron theory. It is known that the δ-field in the constant coupling scheme leads to a larger repulsion in dense neutron-rich matter and to a definite splitting of proton and neutron effective masses, finally influences the stability of the neutron stars. We use density-dependent models of the nucleon-meson couplings to study the properties of neutron star matter and to reexamine the （~-field effects in asymmetric nuclear matter. Our calculation shows that the stability conditions of the neutron star matter can be improved in presence of the δ-meson in the density-dependent models of the coupling constants. The EOS of nuclear matter strongly depends on the density dependence of the interactions.     

Hybrid Bioceramic Coatings of Calcium Phosphate Prepared by Electrodeposition Technique

The electrodeposition of bioceramic coatings of calcium phosphates on metal substrate is a newly developed method for preparing implanted bio-medical devices^[1-2]. It is proposed to have a remarkable higher bioactivity and excellent bio-capability for the electrodeposited bioceramic coating, because it may produce a pure structure and composition of hydraxiapatite (HAP) during electrodeposition process at room temperature. However, the bonding force of electrodeposition bioceramic coating to the metal substrate is too weak. It has become a major problem in developing electrodeposition technique for preparing bioceramic coatings of calcium phosphates on metal substrate. The present work has been emphasized to develop an approach for preparing HAP bioceramic coatings, which has strong bonding force both in the bulk phase of HAP coating and to the metal substrate.