Multiple ionization of the ${\mathrm{Ar}}^{+}\left(3s^{2}3p^5\right)$ ion by a single photon has been investigated in the photon-energy range 250–1800 eV employing the photon-ion merged-beams technique. Absolute partial cross sections were measured for all ${\mathrm{Ar}}^{(1+m)+}$ product-ion channels with $1\le m\le 6$ covering a size range from several tens of Mb down to a few b. Narrow $2p$-subshell excitation resonances were observed in all channels up to quadruple ionization at a photon-energy bandwidth of 52 meV. Double excitations involving a $2p$ and a $3s$ or $3p$ electron were also studied at high resolution and the measurements of the broad $2s$ excitation resonances directly showed their natural widths. Contributions of direct photo double ionization (PDI) to the production of the highest final Ar ion charge states are revealed, with PDI of the $2s$ subshell being mainly responsible for the production of ${\mathrm{Ar}}^{7+}$. The experiment made use of the PIPE setup installed at beamline P04 of the PETRA III synchrotron light source of DESY in Hamburg. The measurements were supported by theoretical calculations to identify the main contributions to the observed cross sections. Comparisons of theory and experiment show remarkable agreement but also hint to additional ionization mechanisms that are not considered in the theoretical models such as core ionization accompanied by excitations with subsequent Auger decays leading to net $m$-fold ionization with $m\ge 4$.

中文翻译：

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在Ar+离子的m-倍(1≤m≤6)光电离中L-壳单核和双核孔产生和衰变的作用

多次电离 ${\mathrm{氩气}}^{+}\left(3{秒}^{2}3{磷}^5\right)$已经使用光子-离子合并束技术在 250-1800 eV 的光子能量范围内研究了单个光子的离子。测量了所有的绝对部分横截面${\mathrm{氩气}}^{(1+米)+}$ 生产通道 $1\le 米\le 6$涵盖从几十 Mb 到几 b 的大小范围。狭窄的$2磷$在 52 meV 的光子能量带宽下，在高达四重电离的所有通道中都观察到了 -subshel​​l 激发共振。双激发涉及$2磷$ 和一个 $3秒$ 或者 $3磷$ 还以高分辨率研究了电子，并测量了广泛的 $2秒$激发共振直接显示了它们的自然宽度。揭示了直接光双电离 (PDI) 对产生最高最终 Ar 离子电荷态的贡献，其中 PDI 为$2秒$ subshel​​l 主要负责生产 ${\mathrm{氩气}}^{7+}$. 该实验利用了安装在汉堡 DESY 的 PETRA III 同步加速器光源的光束线 P04 处的 PIPE 装置。这些测量得到了理论计算的支持，以确定对观察到的横截面的主要贡献。理论和实验的比较显示出显着的一致性，但也暗示了理论模型中未考虑的其他电离机制，例如核心电离伴随激发以及随后的俄歇衰变导致净$米$-倍电离 $米\ge 4$.