等离子体环境中相对论效应对类氢离子光电离过程的影响

Influence of relativistic effects on photoionization process of hydrogen-like ions in plasma environment

本文在偶极近似下计算了Debye等离子体环境中C^(5+),Al^(12+)和W^(73+)离子的光电离截面,重点研究了相对论效应对势形共振、Cooper极小和虚态效应的影响.研究结果表明,相对论效应随核电荷数的增大而增大,使得精细结构劈裂越来越显著,在光电离截面中出现了双共振结构的现象,并且共振峰的大小、宽度和位置的差异都随着核电荷数的增加而越来越大;分截面出现Cooper极小位置的差异也越来越大,在总截面中叠加的极小值越来越浅;出现虚态效应的等离子体屏蔽长度以及低能区光电离截面虚态增强的截面值也存在明显差异.

In this study,the photoionization cross sections of C^(5+),Al^(12+),and W^(73+)ions in a Debye plasma environment are calculated in the dipole approximation.The main emphasis is placed on investigating the influence of relativistic effects on shape resonances,Cooper minima,and virtual state effects.The relativistic effects lead to fine-structure splittings,allowing the appearance of double-shape resonance peaks in the total cross-section.Because the width and energy position of resonance peak are affected by the near critical screening length,the increase of nuclear charge Z leads to the significant differences in the size,width,and position of the double-shape resonance peak.The energy position of Cooper minimum in the photoelectrons is related to the critical screening length corresponding to the final continuum state.Unlike the deeper minima observed in the total photoionization cross-sections for C^(5+)and Al^(12+)ions,for the higher nuclear charge of W^(73+)ions,the significant fine-structure splitting arising from relativistic effects results in substantial differences in the positions of the Cooper minima in the partial cross-sections.Therefore,when superimposed on the total cross section,these minima appear shallower.The W^(73+)ion has a higher nuclear charge,and the screening length related to the virtual state effect is completely different from that of C^(5+)ion and Al^(12+)ion.Moreover,for the same screening length,there is a significant difference in the virtual state enhancement amplitude between C^(5+)ion and Al^(12+)ion in the low energy region.