Atomic structure and collision dynamics with highly charged ions

The research progresses on the investigations of atomic structure and collision dynamics with highly charged ions based on the heavy ion storage rings and electron ion beam traps in recent 20 years are reviewed. The structure part covers test of quantum electrodynamics and electron correlation in strong Coulomb field studied through dielectronic recombination spectroscopy and VUV/x-ray spectroscopy. The collision dynamics part includes charge exchange dynamics in ion-atom collisions mainly in Bohr velocity region, ion-induced fragmentation mechanisms of molecules, hydrogen-bound and van de Waals bound clusters, interference, and phase information observed in ion-atom/molecule collisions. With this achievements, two aspects of theoretical studies related to low energy and relativistic energy collisions are presented. The applications of data relevant to key atomic processes like dielectronic recombination and charge exchanges involving highly charged ions are discussed. At the end of this review, some future prospects of research related to highly charged ions are proposed.     

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.     

Production of highly charged argon ions from a room temperature electron beam ion trap

In this work, highly charged ions have been extracted from the advanced Electron Beam Ion Source (EBIS-A) developed in a scientific cooperation between the Dresden University of Technology and the DREEBIT GmbH Dresden. The charge state distributions of ions extracted from the EBIS-A are measured in the pulse and leaky modes under different operation conditions. Ar¹⁶⁺ ions with current of 2 pA are produced and extracted in the leaky mode. 3×10⁵ Ar¹⁸⁺ ions per pulse are extracted in the pulse mode. The ion charge state distribution is a     

高电荷态金属离子的产生实验研究

为满足兰州重离子加速器的实验要求,在14.5GHz高电荷态ECR离子源上做了一系列产生金属离子的实验,尝试了多种方法,包括炉子加热及MIVOC（Metallic Ion form Volatile Compounds）两种方法,其中,用炉子做的结果较理想。实验主要研究了铜、锌、镍多种电荷态离子的产生,具有代表性的是39euA的13+,30euA的Zn13+和29euA的Ni10+。分别给出了这三种金属离子产生的多电荷态束流峰谱图,以及实验的一些其它现象及结果,并对其进行了讨论与总结。     

高离化态离子及其光电离过程基本特征的理论研究

在Dirac-Slater相对论理论框架下,研究了HCI(高离化态离子)的基本性质及其光电离过程的基本特征.通常HCI的电场非常强,其电子波函数沿靠近核的径向空间被压缩,这极大地改变了相应的物质的性质,使HCI的光电离过程与一般的原子(离子)的相比较有很大的不同:原子核的尺寸效应和相对论效应变得更加重要,而多极效应对光电离截面的影响却趋于减弱.     

高离化态离子及其光电离过程基本特征的理论研究

在Dirac-Slater相对论理论框架下,研究了HCI（高离化态离子）的基本性质及其光电离过程的基本特征. 通常HCI的电场非常强,其电子波函数沿靠近核的径向空间被压缩,这极大地改变了相应的物质的性质,使HCI的光电离过程与一般的原子（离子）的相比较有很大的不同：原子核的尺寸效应和相对论效应变得更加重要,而多极效应对光电离截面的影响却趋于减弱.     

电子束离子阱中高价态离子演化过程的数值模拟

讨论了电子束离子阱(EBIT)中决定高价态离子演化过程的主要物理机制.对EBIT中高价态离 子的演化过程进行了详细的数值计算并与实验进行了比较.讨论了EBIT各种不同的运行参数 对平衡时高价态离子相对丰度和温度的影响. 关键词： 电子束离子阱 高价态离子 数值模拟     

高电荷态离子207Pb36+与金属Nb表面作用产生的二次离子产额

本文报道了利用兰州重离子加速器国家实验室的ECR离子源引出的高电荷态离子207Pb36 入射到金属Nb表面产生的二次离子的实验测量结果.实验发现,二次离子产额Y随入射初动能Ek的增加有先增加后减小的关系,在初动能为576 keV时二次离子产额达到最大.通过对实验点做高斯拟合发现,曲线峰值对应的入射初动能为602 keV.分析表明,这是势能沉积作用与线性级联碰撞过程协同作用的结果.高电荷态离子本身携带的高势能沉积在靶表面引起势能溅射,促进了二次离子的发射;而主导二次离子溅射的过程是动能溅射,它与靶表面的动量沉积(核能损)过程密切相关.     

X-ray spectra induced by slow highly charged Ar q + ions in collision with Nb surface

The X-ray spectra of Nb surface induced by Ar ^q+ (q = 16,17) ions with the energy range from 10 to 20 keV/q were studied by the optical spectrum technology. The experimental results indicate that the multi-electron excitation occurred as a highly charged Ar¹⁶⁺ ion was neutralized below the metal surface. The K shell electron of Ar¹⁶⁺ was excited and then de-excited cascadly to emit K X-ray. The intensity of the X-ray emitted from K shell of the hollow Ar atom decreased with the increase of projectile kinetic energy. The intensity of the X-ray emitted from L shell of the target atom Nb increased with the increase of projectile kinetic energy. The X-ray yield of Ar¹⁷⁺ is three magnitude orders larger than that of Ar¹⁶⁺. Supported by the National Natural Science Foundation of China (Grant Nos.10774149 and 10405025)     

Two photon QED corrections in helium like highly charged ions

An overview of calculations and measurements of the energy levels of helium-like ions is presented. We focus on the two-photon QED effects, and conclude that measurements of the excited states of large Z helium-like ions are desired. This revised version was published online in August 2006 with corrections to the Cover Date.     

纳秒激光电离分子团簇产生高离化离子的激光波长效应

利用脉冲分子束-激光电离-飞行时间质谱仪,在109～1012 W·cm-2激光功率密度条件下,考察了Nd：YAG激光器输出的1 064,532,266 nm波长的激光与苯、氨、硫化氢等团簇的相互作用。发现1 064 nm的激光可以电离分子束产生高离化态的C4+,N5+,S6+等离子;波长为532 nm的激光则电离产生价态较低的C3+,C2+,N3+,N2+, S4+,S3+以及S2+ 等离子;在266 nm波长条件下进行实验,没有产生任何高价离子。提出了一个“多光子电离引发-逆轫致吸收加热-电子碰撞电离”模型来解释高价离子的产生。激光场下电子在团簇内部的逆轫致加热是整个过程的关键步骤,电子被加热的速度正比于激光波长的平方。这可以解释为何长波长的激光有利于更高价态离子的产生。     

低速高电荷态离子40Ar16+与云母表面作用中的电子发射研究

报道了由兰州ECR源提供的低速高电荷离子40Ar16 入射到云母表面产生的电子发射的实验测量结果.结果发现,电子发射产额Y与离子入射角ψ有近似1/tanψ的关系.基于经典过垒模型,我们对这一关系进行了理论分析.实验结果和理论结果相当符合,这就间接说明势能电子发射是低速高电荷态离子作用于表面发射电子的一个主要途径.     

高电荷态金属离子的产生实验研究

 为满足兰州重离子加速器的实验要求，在14.5GHz高电荷态ECR离子源上做了一系列产生金属离子的实验，尝试了多种方法，包括炉子加热及MIVOC（Metallic Ion form Volatile Compounds）两种方法，其中，用炉子做的结果较理想。实验主要研究了铜、锌、镍多种电荷态离子的产生，具有代表性的是39euA的¹³⁺，30euA的Zn¹³⁺和29euA的Ni¹⁰⁺。分别给出了这三种金属离子产生的多电荷态束流峰谱图，以及实验的一些其它现象及结果，并对其进行了讨论与总结。     

X-ray spectra induced in highly charged 40Arq+ interacting with Au surface

By use of optical spectrum technology, the spectra of X-ray induced by highly charged 40Arq+ ions interacting with Au surface have been studied. The results show that the argon Kα X-ray were emitted from the hollow atoms formed below the surface. There is a process of multi-electron exciting in neutralization of the Ar16+ion, with electronic configuration 1s2 in its ground state below the solid surface. The yield of the projectile Kα X-ray is related to its initial electronic configuration, and the yield of the target X-ray is related to the projectile kinetic energy.     

高电荷态离子$lt;sup$gt;126$lt;/sup$gt;Xe$lt;sup$gt;$lt;i$gt;q$lt;/i$gt;+$lt;/sup$gt;引起GaN表面形貌变化研究

用不同电荷态的¹²⁶Xe^q+离子（9≤q≤30）在室温下轰击GaN晶体表面,经原子力显微镜分析表明,当q>18,辐照区域由隆起转为显著的刻蚀.被轰击后的GaN晶体表面形貌主要取决于入射离子的电荷态.同时,样品表面形貌还与入射离子的剂量和入射角有关;在实验参数范围,与入射离子的初动能没有明显关系（180 keV≤E_k≤600 keV）.当入射离子的电荷态q=18,与样品表面法线成60°角倾斜入射和垂直表面入射时,样品的表面几乎没有变化,只是倾斜入射后有很微小的隆起;当q＜18时,样品表面膨胀隆起,粗糙度增强,倾斜入射时表面隆起比垂直入射时更明显,而且都有清晰的峰状分界区;当q＞18时,样品表面被蚀刻呈凹陷状,有明显的齿状刻痕,且侵蚀深度与离子剂量近似呈线性关系,倾斜入射时的刻蚀深度大于垂直入射时的刻蚀深度. 关键词： 高电荷态离子 GaN晶体 原子力显微镜 表面形貌     

高电荷态离子129Xe29+与不同金属表面作用产生的X射线谱

研究了高电荷态离子129Xe29+入射金属Au、Mo、Be表面产生的特征X射线谱。实验结果表明,在入射离子的动能相同时,Au的Mα1-X射线产额比Mo的Lα1-X、Lα2-X、Lβ 1-X射线总产额高,特征X射线的产额随入射离子动能的增加而显著增加;不同动能的Xe29+入射金属Au、Mo、Be表面均未产生Xe的特征X射线。     

高电荷态离子40Arq+与Si表面作用中的电子发射产额

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，用高电荷态⁴⁰Ar^q+(1≤q≤12)离子作用于半导体Si固体表面时的电子发射产额实验测量.实验中，通过改变炮弹离子的电荷态和引出电压选取其不同的势能和动能，系统地研究了入射离子势能沉积和与其在固体中的电子能损对表面电子发射产额的贡献.结果表明，作为引起表面电子发射的两个主要因素，单离子的电子发射产额与炮弹离子在固体表面的势能沉积和电子能损都有近似的正比关系.     

Resonant electron impact excitation of highly charged Fe ions studied with a compact electron beam ion trap

We present extreme ultraviolet spectra of 3s3p–3s3d transitions in Fe¹⁴⁺ observed with a compact electron beam ion trap. The contributions of indirect excitation via a metastable state and resonant excitation are studied by observing the electron energy dependence of the spectra for the energy range of 60–210 eV. The results indicate that the 3s3d ¹D₂ level is directly excited from the 3s² ground state whereas the 3s3d ³D₃ level has a large contribution of the indirect excitation via the 3s3p ³P₂ metastable state. Comparisons with the theoretical excitation cross sections including MNn resonant excitations show good qualitative agreement with the experimental results for the electron energy dependent features.     

反冲原子对低速离子轰击Si表面时电子发射产额的影响

在兰州重离子加速器国家实验室电子回旋共振离子源高电荷态原子物理实验平台上,用低能(0.75keV/u≤EP/MP≤10.5keV/u,即3.8×105m/s≤vP≤1.42×106m/s)He2+,O2+和Ne2+离子束正入射到自清洁Si表面时二次电子发射产额的实验结果.结果表明电子发射产额γ近似正比于入射离子动能EP/MP.在相同动能下,γ(O)γ(Ne)γ(He),对于原子序数ZP比较大的O2+和Ne2+离子,ZP大者反而γ小,这与较高入射能量时的结果截然不同.通过计算不同入射能量下入射离子的阻止能损S,发现反冲原子对激发二次电子的作用随入射离子能量的降低显著增大,这正是导致在较低能量范围内二次电子发射产额与较高入射能量时存在差异的主要原因.     

Ionization and single electron capture in collision of highly charged Ar16+ ions with helium

This paper uses the two-centre atomic orbital close-coupling method to study the ionization and the single electron capture in collision of highly charged Ar^16＋ ions with He atoms in the velocity range of 1.2-1.9 a.u.. The relative importance of single ionization （SI） to single capture （SC） is explored. The comparison between the calculation and experimental data shows that the SI/SC cross section ratios from this work are in good agreement with experimental data. The total single electron ionization cross sections and the total single electron capture cross sections are also given for this collision. The investigation of the partial electron capture cross section shows a general tendency of capture to larger n and l with increasing velocity from 1.2 to 1.9 a.u..