类钠离子光电子角分布的非偶极效应  

Non-dipole effects in the angular distributions of photoelectrons on sodium-like ions

作　　者：马堃[1] 颉录有[2] 张登红[2] 蒋军[2] 董晨钟[2] 

机构地区：[1]黄山学院信息工程学院,黄山245041 [2]西北师范大学物理与电子工程学院,甘肃省原子分子物理与功能材料重点实验室,兰州730070

出　　处：《物理学报》2017年第4期50-57,共8页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11274254,U1332206,U1331122,11464042,11564036);安徽省高校优秀青年人才支持计划重点项目(批准号:gxyq ZD2016301);安徽省高校自然科学研究项目(批准号:KJHS2015B01);黄山学院自然科学研究项目(批准号:2016xskq003)资助的课题~~

摘　　要：基于密度矩阵理论和多组态Dirac-Fock方法,系统地研究了不同入射光子能量下类钠离子(20 Z92)3s,2p_(1/2)和2p_(3/2)子壳层的光电离过程,讨论了辐射场与电子相互作用的多极项对光电子角分布的影响,并给出了光电子角分布的偶极和非偶极参数.结果表明,非偶极项对光电子角分布的影响不仅与入射光子能量有关,而且与靶离子的原子序数、被电离电子的壳层等有着密切的关系.总体上,非偶极项对2p_(1/2,3/2)子壳层光电子角分布的影响大于对3s子壳层光电子角分布的影响;电偶极近似下,入射光子能量、靶离子核电荷数对s子壳层光电子角分布轮廓影响不大,对p子壳层光电子角分布影响较大,在高能光子入射下,低Z离子的p子壳层光电子角分布出现反常的角分布情况;考虑非偶极项之后,p子壳层的反常光电子角分布消失.Photoionization processes widely exist in the astrophysical plasma and the high temperature laboratory plasma. Compared with the traditional photoelectron energy spectrum, the photoelectron angular distribution is not only related to the amplitude of the photoionization channels, but also sensitive to the phases of these channels. So the photoelectron angular distribution contains much more quantum information about the photoionization processes and is used to provide stringent tests of our understanding of basic physical processes underlying gas- and condensed-phase interaction with radiation, as well as a tool to probe physical and chemical structure in solids and surfaces. For a long time, the dipole approximation has been the basis in the study of the photoelectron angular distribution, but with the progress of light source, such as the fourth generation synchrotron facilities, more and more attention is paid to the non-dipole effect of the photoelectron angular distribution. In thispresent work, the photoionization processes of sodium-like ions （20≤Z≤92） are studied for the different incident photon energies based on the multiconfiguration Dirac-Fock method and the density matrix theory. The influences of the non-dipole terms on the photoelectron angular distributions, which arise from the multipole expansion of the electron-photon interaction, are discussed in detail. The relationship between the dipole and non-dipole parameters of the photoelectron angular distribution along with the atomic number is given. It is found that the influence of non-dipole terms on the photoelectron angular distribution is related to the incident photon energy and the atomic number of the target ion and the subshell of the ionized electron. In general, the influences of the non-dipole terms on the photoelectron angular distribution of p subshell are larger than those of the s subshell. In the electric dipole approximation, the s subshell photoelectron angular distribution is nearly independent of the photon energy and n

关 键 词：类钠离子 光电子角分布 非偶极效应 

分 类 号：O562[理学—原子与分子物理]