Abstract

We study the interaction of xenon with an 850 eV photon energy FEL pulse. We compute single-photon ionisation cross sections and Auger rates by adopting to atoms a formalism we previously developed for diatomic molecules. In this formulation, a bound orbital is expressed as a sum of wave functions each corresponding to a different l quantum number. In contrast, in previous formulations only one l quantum number is associated with a bound orbital. As a result, in the non-relativistic regime, the description of the bound states is more accurate in our computations. Employing a Monte-Carlo technique, we find that our results for the ion state yields of xenon compare well with experimental results. Moreover, we find that when xenon is driven by two FEL pulses of the same energy but different pulse duration, higher-charged states are produced in the case of the longer duration and less intense laser pulse. An analysis of the ionization pathways reveals that less single-photon absorptions underlie the formation of each higher-charged state for the longer duration pulse compared to the shorter one. We find that the reason for the formation of higher-charged states for the longer duration pulse is the prevalence of Auger cascades.

Graphical abstract

中文翻译：

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俄歇级联会在X射线自由电子激光脉冲的驱动下导致氙中更高的带电状态

摘要

我们研究了氙与850 eV光子能量FEL脉冲的相互作用。我们通过采用我们先前为双原子分子开发的形式论来计算单光子电离截面和俄歇率。在该公式中，有界轨道表示为波函数的总和，每个波函数对应于不同的1个量子数。相反，在以前的配方只有一个大号量子数与束缚轨道相关。结果，在非相对论体系中，对束缚态的描述在我们的计算中更加准确。使用蒙特卡洛技术，我们发现我们的氙离子态产率的结果与实验结果很好地比较。此外，我们发现，当氙气由两个能量相同但脉冲持续时间不同的FEL脉冲驱动时，在持续时间较长且激光脉冲强度较小的情况下会产生较高的带电状态。对电离途径的分析表明，与较短的脉冲相比，较长的脉冲对每个较高电荷状态形成的单光子吸收较少。我们发现，对于较长持续时间的脉冲，形成较高电荷态的原因是俄歇级联的普遍性。

图形概要