非全裸氟离子与氦原子碰撞中的转移电离过程

采用位置灵敏探测和散射离子 反冲离子飞行时间测量技术 ,测量了强相互作用区氟离子与氦原子碰撞中的转移电离截面与单电子俘获截面之比 .实验发现 ,该比值随作用强度的增加而减小 .在本工作能区 ,转移电离现象可视作一个电子被俘获、另一个电子被电离的两步过程 ;He原子二重电离的主要机制为两步机制. The cross-section ratios of the transfer ionization to the single electron capture of helium induced by fluorine ions in the strong-interaction region were measured by means of the position-sensitive-detecting and the time-of -flight (TOF) technologies. Is is found that the cross section ratios decrease with the increasing of the interaction-strength κ in this work. In the energy range of this work, the transfer ionization can be considered as a two-step process that one electron is captured by projectile...     

非全裸氟离子与氖原子碰撞中的转移电离研究

采用位置灵敏探测和散射离子 反冲离子飞行时间技术测量了强相互作用区F2 + 和F3 + 离子与Ne原子碰撞中的转移电离截面与单电子俘获截面之比 .与Fq+ He实验结果进行了比较 ,并进行了定性讨论. The ratios of the cross-section of the transfer ionization to the single electron capture of Neon induced by F 2+ and F 3+ ions are measured by means of the time-of-flight technologie. In the present energy range, the transfer ionization C1I1 of neon can be considered as a two-step process, in which one electron is captured by projectile and another one is directly ionized, and the transfer ionization C1I2 process should be considered as a subsequent rearrangement of neon following...     

等电荷态离子与He原子碰撞中的转移电离过程研究

采用位置灵敏探测和飞行时间技术测量了等电荷态离子C^q 、N^q 、O^q 、Ne^q (q=4，5，6，7)与He原子碰撞中，转移电离截面与单电子俘获截面的比值Ro研究了相同q入射的情况下，R与入射离子核电荷数Z的依赖关系。在统计蒸发模型的基础上对实验结果进行了解释。     

等电荷态离子与He原子碰撞中的转移电离过程研究

采用位置灵敏探测和飞行时间技术测量了等电荷态离子Cq+、Nq+、Oq+、Neq+(q=4,5,6,7)与He原子碰撞中,转移电离截面与单电子俘获截面的比值R.研究了相同q入射的情况下,R与入射离子核电荷数Z的依赖关系,在统计蒸发模型的基础上对实验结果进行了解释.     

低能高电荷态离子(4≤q≤7)与He碰撞中双俘获与转移电离的截面反转效应

基于入射离子双俘获后势能沉积与双电离靶离子势能的比值定义了势能参数Ω,研究了低能高电荷态离子(q=4,5,6,7)与He原子碰撞系统中双俘获和转移电离反应道的选择规律.研究发现,在Ω坐标下,双俘获和转移电离存在截面反转效应,Ω1.0时双俘获为双电子转移过程主反应道,Ω≥1.0时转移电离成为双电子转移过程主反应道.     

非全裸离子-原子碰撞中的多重电离研究

利用加速器提供的非全裸重离子束 (q=1 - 4)轰击氦、氖和氩原子 ,研究了由非全裸离子引起原子多重电离的有效电荷效应和电荷交换效应 .提出用一个有效电荷来等价描述非全裸入射离子对靶原子的作用 ,将描述全裸离子 -原子碰撞过程的物理模型推广到处理非全裸离子 -原子碰撞过程 ,采用轨道贯穿模型对有效电荷的内在物理机制进行了解释 ,提出一种新的理论方法将多重电离中俄歇过程的贡献予以扣除 .通过研究发现 ,扣除俄歇过程贡献后 ,多重电离截面随入射离子q/ v的变化与多步过程的预言相符.The partially stripped C q+ , O q+ and F q+ ions (q=1-4) delivered by a 2×1.7 MV tandem accelerator were employed to bombard He, Ne and Ar targets. The cross section ratios of multiple ionization to single ionization were measured for different collision systems by using time of flight technique. The effective charge effects and charge exchange processes were studied. By using an effective charge q eff , the multiple ionization processes induced by partially stripped ions could...     

离子原子近距碰撞过程研究

对在北京大学技术物理系核物理与核技术实验１．７ＭＶ串列加速器上进行的有关离子原子碰撞内壳层电离机制的研究进展作了简介。     

类氦离子的电子碰撞电离微分截面

本文主要利用扭曲波玻恩交换近似方法(DBE)计算类氦离子在电子碰撞下,相应不同的末态电子能量分配的电离截面(能量微分截面)。发现对这些微分截面在不同靶电荷及入射能量下,都可用带两个参数的高斯函数αexp(β(x—0.5)²)很好地拟合。还给出两个拟合参数随靶电荷和入射能量的变化曲线,以及讨论了在库仑波玻恩交换近似(CBE)和DBE两种不同近似下所得参数值的差别。计算结果也表阴,在低靶电荷和低入射能量时用DBE计算的必要性。 关键词：     

低电荷态离子原子碰撞过程中的转移电离机理的研究

介绍了使用位置灵敏技术和飞行时间方法研究中低能低电荷态离子-原子碰撞过程中转移电离与单电子俘获过程.对于确定的入射离子电荷态,通过理论分析及与实验数据对比给出了转移电离与单电子俘获截面比R_TS随着入射离子速度V_P的变化规律和转移电离过程中电离的电子主要来自靶原子的最外亚壳层. 关键词： 转移电离 逃离半径 电离半径 俘获半径     

离子与原子碰撞中多电子转移的经典描述

讨论了几各地独立电子模型（ＩＥＭ）描述离子与原子碰撞中电子转移的经典模型，即Ｂｏｈｒ－Ｌｉｎｄｈａｒｄｔ模型，过垒模型ＯＢＭ和分子库仑垒模型ＭＣＢＭ。较详细阐述了描述碰撞过程的经典物理图象，着重讨论了ＭＣＢＭ描述的多电子转移过程，分析了几各模型的特点和适用性，最后在考虑了入射离子量子数亏损和出射过程电子束缚能移动的修正后，给出了修正后的ＭＣＢＭ的计算结果，并与Ｎｉｅｈａｕｓ的计算结果玫实验结果进行     

Investigation of the transfer ionization process in collisions of partially stripped ions on He

In this paper a projectile ion-recoil ion coincidence technique is used to investigate the transfer ionization processes in collisions of 0.22--6.30~MeV C^{q + } ions and 0.25--6.35~MeV O^{q + } ions (q=1, 2, 3, 4) with the He atom separately. The cross section ratio f of transfer ionization to single electron transfer is measured, and the dependence of f on both charge state q and energy E of the projectiles is investigated. The electron-structure and the mechanisms leading to transfer ionization affect the dependence of f on q and E. Our measurements, along with other data published previously, suggest a similar dependence of f on charge state and energy of projectile for partially stripped ions over a large energy range. The maximum value of f is approximately 0.17q^{0.60}; the energy corresponding to maximum f is about 160q^{0.60}~keV/u.     

Investigation of transfer ionization in collisions of partially stripped carbon ions with helium at low to intermediate velocities

The ratios of transfer ionization (TI) to single-electron capture (SC) cross sections have been measured for the collisions of partially stripped C^q+ ions (q=1--4) with He. The collision velocity ranges from 0.7 to 4.4v₀ (v₀ is the Bohr velocity). The projectile-ion and recoil-ion coincidence technique is used to separate the processes of TI and SC. The ratios reach the maximum when the velocity is about 3.7v₀ This can be explained qualitatively based on the two-step mechanism. The experimental results are also compared with the results calculated using the classical trajectory Monte Carlo (CTMC) method. The CTMC results are in agreement with the experimental data basically. The discrepancies in higher velocity region are interpreted by the effective charge effect.     

Transfer ionization in isocharge sequence ion and Ne collisions

The dependence of the ratio R1 for transfer ionization to single capture for Cq+, Nq+, Oq+, Neq+ ions on Ne target upon the electronic structure of the projectile is studied. For Aq+-Ne collisions the ratio R1 decreases as the atomic number Z of the projectile increases for q=4,5,6,7 sequences which provides strong evidence for the increase of the binding energy of the target valence electron after single electron capture. The increase in binding energy depends both upon the atomic number of the projectile and the target atom.     

低能Ar9+离子与Na原子碰撞反应中的多电子转移过程

利用近代物理研究所新建的原子物理实验平台,采用位置灵敏探测和散射离子-反冲离子飞行时间符合技术,研究了180 keV的Ar9+离子与Na原子碰撞中的多电子转移过程,对实验结果做了分析和简单的讨论,并同修正后的分子库仑过垒模型结果进行了比较.     

低能He2+-He碰撞体系转移电离机理的实验研究

利用冷靶反冲离子动量谱仪,对低能He²⁺-He碰撞反应中产生的反冲靶离子和炮弹离子进行了符合测量,根据反冲靶离子的动量,研究了转移电离过程中的电荷转移机理.实验结果表明：在20—40 keV能量范围内,靶原子上的一个电子俘获到炮弹离子的基态,另一个电子直接发射到靶的连续态的直接电离及另一个电子俘获到炮弹离子的连续态的过程(ECC)是最主要的转移电离机理,且ECC过程主要发生在大碰撞参数条件下;炮弹离子俘获两个电子处在双激发态的自电离过程的贡献很小. 关键词： 冷靶反冲离子动量谱仪 转移电离机理 离子原子碰撞     

Transfer ionization cross-sections measured in collisions of highly charged argon ions with neon target

: Multiple electron transfer processes are studied for Arq+n- Ne (q= 8, 9, 11, 12) collisions by using multi-parameter coincidence techniques. Various electron transfer processes are identified experimentally and the related cross-sections are measured. The dependence of transfer ionization cross-sections on the recoil charge states is compared with the results from the modified molecular classical overbarrier model. It is found that the modified model described the experimental results reasonably.     

用紧耦合方法研究C4+和O6+与He原子碰撞

用双中心原子轨道紧耦合方法计算了C4+-He以及O6+-He碰撞的单俘获总截面,入射离子的能量范围为10～100keV/amu,所得计算结果在实验误差范围内与实验值很好符合.对满壳层入射离子,研究了单俘获截面随入射离子电荷态的变化,并讨论了原子轨道展开波函数数目对计算结果的影响.p     

Multiple ionization of argon accompanied by electron loss and capture of 0.22-6.35 MeV C^q＋ ions

In this paper a projectile ions recoil ions coincidence technique is employed to investigate the target ionization and projectile charge state changing processes in the collision of 0.22-6.35 MeV Cq^＋ （q = 1 - 4） ions with argon atoms. The partial cross section ratios of the double, triple, quadruplicate ionization to the single ionization （or the single capture） of argon associated with single electron loss （or single electron capture） by the projectile are measured and compared with the previous experimental results. In the present experiment, it is observed that the ratios of ionization cross sections R associated with single loss and single capture depend strongly on the projectile charge state and vary significantly with different reaction channels as impact energy increases. In addition, this paper gets empirical scaling laws for the ionization cross section ratios R corresponding to the projectile single loss and finds that the ratios of the double ionization to the single ionization associated with single electron capture remain constant in the present energy range.     

Cross sections of Oq+（q=1-4） electron loss in collisions with He,Ne and Ar

Electron-loss cross sections of O q+(q = 1 4) colliding with He,Ne and Ar atoms are measured in the intermediate velocity regime.The ratios of the cross sections of two-electron loss to that of one-electron loss R 21 are presented.It is shown that single-channel analysis is not sufficient to explain the results,but that projectile electron loss,electron capture by the projectile and target ionization must be considered together to interpret the experimental data.The screening and antiscreening effects can account for the threshold velocity results,but cannot explain the dependence of the ratio R 21 on velocity quantitatively.In general,the effective charge of the target atom increases with velocity increasing because the high-speed projectile ion can penetrate into the inner electronic shell of target atom.Ne and Ar atoms have similar effective charges in this velocity regime,but He atoms have smaller ones at the same velocities due to its smaller nuclear charge.