Static-field ionization model of He-like ions for diagnostics of light-field intensity
Static-field ionization model of He-like ions for diagnostics of light-field intensity
复制标题
DOI：
10.1103/physreva.102.013112
复制
发表时间：
2020-07
影响因子：
2.9
通讯作者：
E. Lötstedt;M. Ciappina;K. Yamanouchi
中科院分区：
文献类型：
--
作者：
E. Lötstedt;M. Ciappina;K. Yamanouchi
我们研究核电荷数在$2\leq Z\leq36$范围内的类氦离子的静电场电离。同时考虑了隧穿和过垒两种机制。我们通过三种近似方法计算电离率：一种基于佩列列莫夫 - 波波夫 - 捷连季耶夫（PPT）公式的拟合公式、以$1/Z$为幂次的微扰展开以及单活性电子近似，并将它们与由多组态含时哈特里 - 福克（MCTDHF）方法计算得到的参考电离率进行比较。发现基于PPT的拟合公式和三阶微扰理论计算得到的电离率与MCTDHF方法计算得到的电离率的相对偏差约为10%。通过比较单活性电子电离率和包含多电子效应的参考电离率，我们定量地讨论了电离过程中交换相互作用的贡献。我们发现，在忽略交换相互作用的单活性电子近似下，对于氦原子，电离率被高估了30%，对于类氦氪原子，高估了2%，这表明交换相互作用效应的大小大致与$1/Z$成正比。
We study static-field ionization of He-like ions with nuclear charge number in the range of $2\ensuremath{\le}Z\ensuremath{\le}36$. Both the tunneling and over-the-barrier regimes are considered. We calculate the ionization rates by three approximate methods: a fitting formula based on the Perelemov-Popov-Terent'ev (PPT) formula, a perturbative expansion in powers of $1/Z$, and a single-active electron approximation, and compare them with reference ionization rates computed by the multiconfiguration time-dependent Hartree-Fock (MCTDHF) approach. The relative deviation of the rates computed by the PPT-based fitting formula and the third-order perturbation theory from the rates computed by the MCTDHF approach is found to be around 10%. We discuss quantitatively the contribution from the exchange interaction during the ionization by comparing the single-active electron rates and the reference rates in which multielectron effects are included. We find that a single-active electron approximation, where the exchange interaction is neglected, results in the overestimation of the ionization rates by 30% for He and 2% for He-like Kr, showing that the magnitude of the effect of the exchange interaction scales approximately as $1/Z$.