关键词: 类钠离子/
光电子角分布/
非偶极效应
English Abstract
Non-dipole effects in the angular distributions of photoelectrons on sodium-like ions
Ma Kun1,Xie Lu-You2,
Zhang Deng-Hong2,
Jiang Jun2,
Dong Chen-Zhong2
1.School of Information Engineering, Huangshan University, Huangshan 245041, China;
2.Key Laboratory of Atomic and Molecular Physics and Functional Materials of Gansu Province, College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070, China
Fund Project:Project supported by the National Natural Science Foundation of China (Grant Nos.11274254,U1332206,U1331122,11464042,11564036),the Key Project for Young Talents in College of Anhui Province,China (Grant No.gxyqZD2016301),the Natural Science Research Project of Anhui Province,China (Grant No.KJHS2015B01),and the Natural Science Research Project of Huangshan University,China (Grant No.2016xskq003).Received Date:28 August 2016
Accepted Date:24 November 2016
Published Online:05 February 2017
Abstract: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 (20Z92) 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 nuclear charge number, but this situation is not for the p subshell. With the increase of photon energy, an abnormal angular distribution is found for the p subshell photoelectron. However, if the non-dipole effects are included, the abnormal photoelectron angular distribution of p subshell disappears and the photoelectron distribution has maximum values respectively near 45o and 135o with respect to the polarization vector of incident light, that is, the photoelectron distribution has an obvious forward scattering characteristic.
Keywords: sodium-like ion/
the angular distribution of photoelectron/
non-dipole effects
