Two-step mechanisms in ionization-excitation of He studied by binary (e,2e) experiments and second-Born-approximation calculations
Two-step mechanisms in ionization-excitation of He studied by binary (e,2e) experiments and second-Born-approximation calculations
复制标题
DOI：
10.1103/physreva.75.052701
复制
发表时间：
2007-05
影响因子：
2.9
通讯作者：
N. Watanabe;M. Takahashi;Y. Udagawa;K. Kouzakov;Y. Popov
中科院分区：
文献类型：
--
作者：
N. Watanabe;M. Takahashi;Y. Udagawa;K. Kouzakov;Y. Popov
报道了 He 电离激发过程的电子动量能谱研究。在 1240 和 $4260\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ 的冲击能量下，相对于基态离子态，测量了跃迁到激发离子态的对称非共面 $(e,2e)$ 横截面。实验结果显示出对冲击能量的显着依赖性。这提供了强有力的证据表明涉及高阶效应。进行了二次近似计算，并将其结果与实验结果进行了比较。结果表明，两步机制在电离激发过程中起着至关重要的作用。
An electron momentum spectroscopy study on ionization-excitation processes of He is reported. The symmetric noncoplanar $(e,2e)$ cross sections for transitions to excited ion states have been measured relative to that to the ground ion state at impact energies of 1240 and $4260\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$. The experimental results exhibit a marked dependence on the impact energy. This provides strong evidence that higher-order effects are involved. Second-Born-approximation calculations are performed and their results are compared with the experimental ones. It is shown that the two-step mechanisms play crucial roles in the ionization-excitation processes.