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中国物理学会期刊

W13+离子的电子碰撞单电离截面的理论研究

Theoretical investigation of electronimpact single ionization of W13+ ion

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  • 本文采用细致能级扭曲波(level-to-level distorted-wave, LLDW)方法详细地计算了W13+离子基组态Kr4d105s24f13和亚稳态Kr4d105s24f125p的电子碰撞单电离(EISI)截面,主要包括了直接电离(DI)和激发自电离(EA)截面对EISI截面的贡献。为提升计算可靠性,我们在原子结构计算中引入了组态相互作用。本文还重点计算了长寿命亚稳态对EISI截面的贡献,其中母离子束中长寿命亚稳态所占的分数是通过理论模型来确定的。将本文的计算结果与Schury等人的实验结果和理论结果进行比较,发现在考虑了长寿命亚稳态的贡献后本文的计算结果和Schury等人的实验结果吻合地很好。

     

    Electron-ion collision is one of the fundamental processes in atomic and molecular physics, and the study of this process can provide insight into the mechanism of electron-atom/ion interaction. It has important applications in plasma physics and astrophysics. Accurate electron-impact cross-sections are important in plasma modeling. In generally, total EISI cross-sections consists of the direct ionization (DI) and the indirect ionization processes, with the latter further divided into excitation autoionization (EA), resonant excitation double auto-ionization (REDA) and resonant excitation auto- double ionization (READI) processes. In this work, the electron-impact single ionization (EISI) crosssections for the ground state Kr4d105s24f13 of W13+ ions are calculated in detail by using the level-to-level distorted-wave (LLDW) method, which mainly includes the contributions of direct ionization (DI) and excited auto-ionization (EA) cross-sections to the EISI cross-sections. Our computational results demonstrate that when configuration interaction are incorporated, the calculated values show excellent agreement with experimental data for electron impact energies exceeding 500 eV. However, significant discrepancies persist near the ionization threshold. we have confirmed that these discrepancies primarily originate from the presence of long-lived metastable ions. To achieve better agreement with experimental observations, we further calculated EISI cross-sections for 71 energy levels of the metastable state 4 d10 5 s2 4 f12 5p with lifetimes greater than 1.5×10-5s. The total EISI cross-sections of these 71 energy levels were obtained by theoretical fitting and compared with the experimental results by Schury et al. (Figure), and it was found that our results were in good agreement with the experimental results of Schury et al. after considering the contribution of long-lived metastable.

     

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