129Xeq+轰击N型和P型Si表面时的电子发射产额研究

在兰州重离子加速器国家实验室测量了1.8 MeV Xeq+离子分别轰击N型和P型Si两种靶材表面时的电子发射产额。实验中,通过改变入射离子的电荷态,研究了入射离子势能沉积对两种靶材表面电子发射产额的贡献。结果发现同一离子入射时,N型Si表面的电子发射产额高出P型Si表面的电子发射产额约12.5%;对于具有相同入射动能的Xeq+离子,两种靶材表面的电子发射产额均随着入射离子势能的增加而线性增加。此外,还测量了3.4 MeV Xeq+离子分别轰击以上两种靶材时的电子发射产额,得到了类似的结果。本文利用功函数分别从动能电子发射和势能电子发射两个角度对实验结果进行了分析讨论。The electron emissions from N-type Si and P-type Si induced by 1.8 MeV 129Xeq+are measured in the National Laboratory of Heavy Ion Research Facility in Lanzhou,The contribution to electron emission yield from potential energy of incident ions is studied through changing the charge state of incident ions.The results show that for the same incident ion,electron emission yield of N type Si surface is higher than that of P-type Si surface about 12.5%.For incident ions with the same kinetic energy,both electron emission yields of two targets increase linearly with incident ion energy.In addition,the electron emissions induced by 3.4 MeV 129Xeq+from N-type Si and P-type Si mentioned above are measured,which give similar results.The experimental results are analyzed and discussed using work function from two angles of the kinetic electron emission and the potential energy electron emission.     

不同能量的高电荷态Ar12+离子辐照对Au纳米颗粒尺寸的影响

报道了在兰州重离子加速器国家实验室电子回旋共振离子源原子物理实验平台上,在室温（293.15K）条件下,用固定剂量（4.3×10¹¹/cm²）的高电荷态⁴⁰Ar¹²⁺离子,辐照沉积在厚度为300nm的金膜表面上、平均直径约为35.3nm的Au纳米颗粒,使其大小发生改变的实验结果.实验中,通过改变入射离子的引出电压,选择不同的能量,利用原子力显微镜（AFM）对辐照前后颗粒的形态和大小进行表征,系统地研究了辐照后Au纳米颗 关键词： 纳米颗粒 高电荷态离子 离子辐照 临界能量     

质子轰击钨靶表面时的电子发射产额与靶温度的相关性研究

在中国科学院近代物理研究所兰州重离子加速器国家实验室测量了能量为50～250 keV的质子入射不同温度下钨靶表面的电子发射产额。实验结果发现,不同能量的质子引起的电子发射产额均随着靶温度的升高而降低;利用功函数对温度的依赖性定性地解释了该结果。在不同靶温度下,总电子发射产额与电子能损的比值随着质子能量的增加而逐渐变小;利用靶原子不同壳层中电子之间的电离竞争机制来解释实验结果。     

从美国伊利诺伊大学香槟分校的大学物理课程教学特点浅谈我国大学物理教学改革

从美国伊利诺伊大学香槟分校(UIUC)的大学物理课程的设置、教学环境的预设、教学的整个过程等详细阐述了其教学特点,并提出了我国大学物理改革的几点具体措施.     

Electron emission induced by keV protons from tungsten surface at different temperatures

The electron emission yield is measured from the tungsten surface bombarded by the protons in an energy range of 50 keV-250 keV at different temperatures. In our experimental results, the total electron emission yield, which contains mainly the kinetic electron emission yield, has a very similar change trend to the electronic stopping power. At the same time, it is found that the ratio of total electron emission yield to electronic stopping power becomes smaller as the incident ion energy increases. The experimental result is explained by the ionization competition mechanism between electrons in different shells of the target atom. The explanation is verified by the opposite trends to the incident energy between the ionization cross section of M and outer shells.     

Slow highly charged ion O4+ induced electron emission from clean solid surfaces

The total electron emission yields following the interaction of slow highly charged ions (SHCI) O⁴⁺ with different material surfaces (W, Au, Si and SiO₂) have been measured. It is found that the electron emission yield γ increases proportionally with the projectile velocity v ranging from 5.36×10⁵m/s to 10.7× 10⁵m/s. The total emission yield is dependent on the target materials, and it turns out to follow the relationship γ(Au)>γ(Si)>γ(W). The result shows that the electron emission yields are mainly determined by the electron stopping power of the target when the projectile potential energy is taken as a constant, which is in good agreement with the former studies.     

对称破坏分歧点的分裂迭代方法

构造了求解对称破坏分歧点的扩充系统，采用分裂分块迭代方法逼近对称破坏分歧点，并对2.Box Brusselator反应模型进行了数值模拟．     

A NEW APPROXIMATE INERTIAL MANIFOLD AND ASSOCIATED ALGORITHM

In this article the authors propose a new approximate inertial manifold(AIM) to the Navier-Stokes equations. The solutions are in the neighborhoods of this AIM with thickness δ=o(h2k 1-ε). The article aims to investigate a two grids finite element approximation based on it and give error estimates of the approximate solution where (h, h*) and (k, m) are coarse and fine meshes and degree of finite element subspaces, respectively. These results are much better than Standard Galerkin(SG) and nonlinear Galerkin (NG) methods. For example, for 2D NS eqs and linear element, let uh,uh,u* be the SG, NG and their approximate solutions respectively, then and h*≈h2 for NG, h*≈h3/2 for theirs.     

斜入射条件下光栅衍射现象的分析

分析和研究了在特殊斜入射条件的光栅衍射现象,并阐明了在利用光栅测量波长实验中由于特殊斜入射所引起的系统误差。     

光电离过程中Fe靶和V靶特征辐射的角相关研究

在发射角120°—170°的范围内,应用硅漂移探测器以10°为间隔对中心能量为13.1 keV的韧致辐射诱发Fe靶和V靶发射的典型K系X射线光谱进行了测量.得到特征X射线Kα和Kβ的特征谱线,考虑探测器对特征X射线的探测效率、靶对入射光子和出射光子吸收的校准及大气对特征X射线的吸收后,结果显示不同探测角度下Kβ与Kα的强度比为一常数.将本次实验探测角度为150°时的Kβ/Kα强度比值的实验值、理论计算值和Ertuğral的实验结果进行对比,发现实验结果与预期相符.对比不同探测角度下的强度比变化趋势推断特征X射线的角度依赖关系,分析认为Kα和Kβ在探测范围内是各向同性发射的.