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题名 低速高电荷态离子在晶体Al(111)面掠射的沟道效应与能量损失的计算机模拟
姓名 陈春花
院系 物理科学与技术学院
专业 粒子物理与原子核物理
学位名称 理学硕士
外文题名 Computer simulation of Channeling effect and energy loss for Slow Highly Charged Ions Grazing on the Crystal Al(111) Surface
第一导师姓名 胡碧涛
关键词 掠角散射;能量损失;沟道效应;过垒模型;镜反射模型
外文关键词 Grazing scatter;Energy Loss;Channelling effect;classical-over-barrier model;specular reflection mode
学科 理学
摘要 随着产生低速高电荷态离子源性能的提高,高电荷态离子与固体间的相互作用正在受到越来越多地关注。特别是,关于高电荷态离子在固体表面的散射及相关问题的研究已经成为这一领域的热点,它不仅揭示了一些基本的理论问题,同时也与离子束表面改性、表面结构分析、原子溅射沉积薄膜和纳米刻蚀与印刷等技术的应用紧密相关。 本论文用计算机模拟的方法研究了低速高电荷态离子在金属表面掠射的整个运动过程中的能量损失问题。能量损失主要来源于以下几个方面:镜像电荷的加速过程,入射离子与固体的电荷交换过程,金属表面的电子响应过程等。同时,本文还研究了低速高电荷态离子在金属表面掠射的沟道效应以及其对能量损失的影响。 本论文模拟的基本思想是在经典过垒模型下,采用蒙特卡罗方法(Monte Carlo)来模拟入射离子与固体间电荷交换过程的随机性,并将入射离子连续的运动过程离散化,在每一个步长中将入射离子的运动近似看成是匀加速直线运动。同时,本文利用matlab程序计算金属表面对入射离子的电子阻止本领,将其数值应用到以上程序中来计算整个过程的电子能量损失。 本文通过以上的模拟过程得出了各个过程的能量损失以及能量损失与不同的入射与出射参数的函数关系。由于本文考虑了入射离子与金属的电荷交换能损,故而计算得到的能量损失与初始电荷态的关系与实验值比前人符合得更好。同时,本文通过低速高电荷态离子在金属表面沟道效应的研究得出金属表面结构对入射离子能量损失的影响,从而为表面结构的分析提供了进一步的理论依据。 本论文主要分为四个部分:第一部分给出了低速高电荷态离子与固体作用的研究方向与研究进展,第二部分为低速高电荷态离子与固体作用过程能量损失的理论背景,第三部分给出低速高电荷态离子在金属表面掠射沟道效应的理论背景,最后一部分是我们的模拟结果及讨论。
外文摘要 With the development of the technology of the sources for the slow highly charged ions (SHCIs), the interaction of slow, highly charged ions with solid has absorbed more and more attentions,especially, the studies of the ion-surface scattering and the aspects related to it Research in this field not only focused on fundamental problems, but also has resulted in astonishing progress in the applications, such as surface modification, surface structure analysis and the thin solid film deposited by the atom sputtering. This article is bending itself to the computer simulation of energy loss during the slow highly charged ion grazing on metal surface. In our simulation, the energy loss mainly comes from three major processes: the image acceleration of highly charged ions, the charge exchange processes of highly charged ions with surfaces, and the induced electrons by the incident ions and so on. In addition, we still consider the surface channeling effect of the slow highly charged ions interaction with crystal metal surface under grazing angle and the affect to the energy loss. The main idea of the simulation is adopting Monte Carlo method and the classical over barrier model to simulate the randomicity of the charge exchange processes between projectile and metal surfaces and the dispersing of projectile’s continuum movement. In each step, the movement of projectile is considered to a uniform acceleration. At the same time, we calculate electronic stopping power by matlab code with specular reflection model, with which we get electronic energy loss in the mentioned code. Through the simulation, we get the energy loss of different processes and the function of different incident parameter and total energy loss,especially,due to the charge exchange energy we calculated the calculated total energy loss agrees with experimental data very well. Moreover,we find that the total energy loss of the slow highly charged ions grazing on crystal metal surface strongly depends on the structure of the lattice. Thus, it could be used as the additional theoretic reason for the solid surface analysis. This article is mainly composed of four sections. One is devoted to the research affects and status of the interaction of slow highly charged ions with surfaces; the second part considers the theory description of energy loss of the slow highly charged ions with metal surface; the third part concerns the theory description of surface channeling effect of slow high...
研究领域 高离化态物理
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