Energy Loss and charge exchange for medium energy ions in a large-angle collision

大角度碰撞中中能离子的能量损失和电荷交换

• 批准号: 13640411
• 负责人: KIDO Yoshiaki
• 金额: $ 2.05万
• 依托单位: Ritsumeikan University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2001
• 资助国家: 日本
• 起止时间: 2001 至 2003
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13640411/
• 关键词: Medium energy ion scattering; Carge exhange; Inelastic energy loss; Lare-angle collision; Inter-atomic potential; 大角・単回散乱; 中エネルギーヘリウムイオン

Systematic understanding the charge exchange, inelastic energy loss and spectrum shape for medium energy ions scattered to a large-angle is indispensable to extract the quantitative information about the suiface structure and lattice dynamics from the energy spectra obseived for the ions scattered from solid surfaces. Unfortunately, however, it is impossible to measure directly the above physical quantities using gas targets, because of the extamely smali target densi and scattering cross sections. In this study, we measured the charge state distributions (CSDs), inelastic energy loss and spectrum shapes for He ions scattered to a large-angle at single ciystal surfaces using a toroidal electrostatic analyzer with an excellent energy resolution (Δ E =9 x 10^<-4>). The single ciystal targets used here are MgO(001), KI(001), BbI(001), B-type NiSi_2(111) and Si(111)-√<3> x√<3>-Sb. We also measured the elastic scattering cross sections with a solid state detector for He and Ne ions scattere … More d to a large-angle from Ni, Sb and Hf atoms. The present study has revealed the following points :(1) The CSDs for He ions scattered to a large-angle from the atoms on top of solid surfaces are not equilibrated and the smaller the Z-number of target atoms, the larger the average charge. The average charges for He ions scattered from high-Z atoms (z 【greater than or similar】20) observed agree with the semi-empirical formula proposed by Marion-Young [ii within experimental enors (±20%).(2) The observed avemge charges of He ions after a large-angle collision are scaled as a frmnction of ∫^∞_<r_<min>> P_e(r(t))dr/v(t), where P_e (r(t)) is the target electron density at r(t), R_<min> is the closest distance and v(t) is the He velocity.(3) The average charges of the He and Ne ions scattered from top most atoms are dependent on exit angle and the smaller the the exit angle (scaled from the surface plane), the smaller the average charges (reaching an equilibrium value).(4) The inelastic energy loss for he ions scattered from the Sb atoms were measured directly using the Si(111)-√<3> x√<3>-Sb. The result obtained agrees the theoretical calculation by Schiwietz using the coupled channel method.(5) In the case of a large-angle collision between a heavy ion such as Ne and a high-Z atom, the differential scattering cross sections are enhanced due to dynamical change of the target electron density distributions induced by formation of a molecular oitital during the collision Less

不幸的是，系统地了解大角度散射的中等能量离子的电荷交换、非弹性能量损失和光谱形状对于从固体表面散射离子的能谱中提取有关表面结构和晶格动力学的定量信息是必不可少的。然而，由于目标密度和散射截面极小，不可能直接使用气体目标测量上述物理量。在本研究中，我们测量了电荷态分布。 （CSD），使用环形静电分析仪在单晶体表面大角度散射的 He 离子的非弹性能量损失和光谱形状，此处使用的目标具有出色的能量分辨率（Δ E = 9 x 10^<-4>）。分别为 MgO(001)、KI(001)、BbI(001)、B 型 NiSi_2(111) 和Si(111)-√<3> x√<3>-Sb 我们还使用固态探测器测量了 He 和 Ne 离子从 Ni、Sb 和 Hf 散射到大角度的弹性散射截面。本研究揭示了以下几点：（1）从固体表面原子大角度散射的He离子的CSD不平衡，目标原子的Z数越小，CSD越大。平均收费。观察到的从高Z原子（z【大于或相似】20）散射的He离子的平均电荷与Marion-Young提出的半经验公式一致[ii在实验误差范围内（±20%）。（2）观察到的大角度碰撞后 He 离子的平均电荷缩放为 ∫^∞_<r_<min>> P_e(r(t))dr/v(t) 的函数，其中P_e (r(t)) 是 r(t) 处的目标电子密度，R_<min> 是最近距离，v(t) 是 He 速度。 (3) 从最上面的原子取决于退出角，退出角越小（从表面平面缩放），平均电荷越小（达到平衡值）。（4）从 Sb 原子散射的 he 离子的非弹性能量损失为直接使用测量Si(111)-√<3>x√<3>-Sb 所得结果与Schiwietz使用耦合通道法的理论计算一致。 (5)在重离子如大角度碰撞的情况下。 Ne 和高 Z 原子，由于碰撞过程中形成分子原子而引起目标电子密度分布的动态变化，从而增强了差异散射截面。

项目成果

Y.Hoshino, Y.Kido: "Dynamic response of target electrons on elastic scattering cross sections for heavy ion impact on a high-Z atom"Physical Review. A68. 012718-1-012718-5 (2003)

Y.Hoshino、Y.Kido：“重离子撞击高 Z 原子时目标电子在弹性散射截面上的动态响应”物理评论。

Y.Kido, S.Semba, Y.Hoshino: "Charge exchange for medium energy He and Ne ions in a large-angle collision at solid surfaces"Current Applied Physics. 3. 3-7 (2003)

Y.Kido、S.Semba、Y.Hoshino：“固体表面大角度碰撞中中等能量 He 和 Ne 离子的电荷交换”当前应用物理学。

城戸 義明: "イオン工学ハンドブック 第2章5節(イオンビーム)"イオン工学研究所. 1126 (2003)

Yoshiaki Kido：“离子工程手册第2章第5节（离子束）”离子工程研究所1126（2003）。