The angular distribution and polarization of the x-ray photoemission of highly charged helium-like ions is studied following the K-LL dielectronic recombination of initially hydrogen-like ions.Calculation is carried o...The angular distribution and polarization of the x-ray photoemission of highly charged helium-like ions is studied following the K-LL dielectronic recombination of initially hydrogen-like ions.Calculation is carried out within the framework of the density matrix theory combined with the multiconfiguration Dirac-Fock approach.Attention is paid to magnetic sublevel alignment in the resonant intermediate state and to its nonuniform radiative decay processes.It is shown that the Breit interaction between the incident and target electrons plays a significant role for the alignment of the resonant state and thus causes a substantial change in the x-ray emission characteristic,when compared to the incorporation of only the(non-relativistic)Coulomb interaction.The most prominent difference in alignment parameter is found in the 2s2p_(1/2) J=1 resonant state for a wide range of atomic numbers from 9 to 92.For this resonant state of helium-like ions,the Breit interaction becomes significant for ions with nuclear charge Z~30 already.展开更多
Detailed calculations are carried out for the electron-impact excitation cross sections from the ground state to the individual magnetic sublevels of the 1s2s^(2)2p^(3)/2 J=2 excited state of highly-charged beryllium-...Detailed calculations are carried out for the electron-impact excitation cross sections from the ground state to the individual magnetic sublevels of the 1s2s^(2)2p^(3)/2 J=2 excited state of highly-charged beryllium-like ions by using a fully relativistic distorted-wave(RDW)method.The contributions of the Breit interaction to the linear polarization of the 1s2s^(2)2p^(3)/2 J=2→1s22s2 J=0 magnetic quadrupole(M2)line are investigated systematically for the beryllium isoelectronic sequence with 42≤Z≤92.It is found that the Breit interaction depolarizes significantly the linear polarization of the M2 fluorescence radiation and that these depolarization effects increase as the incident electron energy and/or the atomic number is enlarged.展开更多
The multi-configuration Dirac-Fock method is employed to calculate the energy levels and transition probabilities for the electric dipole allowed (El) and forbidden (M1,E2) lines for the 4s^(2) 4p,4s4p^(2) and 4s^(2) ...The multi-configuration Dirac-Fock method is employed to calculate the energy levels and transition probabilities for the electric dipole allowed (El) and forbidden (M1,E2) lines for the 4s^(2) 4p,4s4p^(2) and 4s^(2) 4d configurations of highly charged Ga-like ions from Z =68-95.The lifetimes of the 4s^(2) 4p^(2) P3/2 level of the ground configuration are also derived.Based on our calculations,it is found that the energy level of the 4s2 4p 2P3/2 is higher than that of the 4s4p24P1/2 for the high-Z Ga-like ions with Z ≥ 74,so as to generate an energy crossing at Z =74.The effect of the energy crossing is important to the calculation of the 4s^(2) 4p^(2) P3/2 level lifetime for Ga-like ions with Z≥ 74.展开更多
The radiative and Auger decay processes of K-shell ionized Np ions are studied theoretically using the flexible atomic code(FAC).Relativistic effects,Breit interaction,QED corrections and nuclear finite mass and volum...The radiative and Auger decay processes of K-shell ionized Np ions are studied theoretically using the flexible atomic code(FAC).Relativistic effects,Breit interaction,QED corrections and nuclear finite mass and volume effects are considered systematically.The resulting calculated K x-rays and Auger spectra of Np are compared with the measured spectra emitted after the electron-capture(EC)-decay of mass-separated ^(237)Pu.The general consistency between theory and experiment is good;the relative intensities and relative positions of the peaks in the measured spectra are reproduced with good accuracy,in spite of the existence of different ways to produce the primary K-shell vacancy,enabling identification of the observed structure in the experimental spectra.We find that most of the radiative transition rates are greater than the Auger transition rates,and the latter decrease rapidly with the transfer of initial vacancies to the outer shell.展开更多
In this work, the KLL dielectronic recombination （DR） processes of highly charged He-like to O-like xenon ions are studied systematically by using a DR program, which is based on the multi-configuration Dirac-Fock ...In this work, the KLL dielectronic recombination （DR） processes of highly charged He-like to O-like xenon ions are studied systematically by using a DR program, which is based on the multi-configuration Dirac-Fock （MCDF） method. The KLL DR resonant energies and the corresponding resonant strengths are calculated, emphasizing especially the effect of the Breit interaction on the DR strengths. The theoretical KLL DR spectra are obtained and compared with the latest experimental results obtained in the Shanghai Electron Beam Ion Trap.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos 11274254,91126007,10964010,11264033,and 11147018.
文摘The angular distribution and polarization of the x-ray photoemission of highly charged helium-like ions is studied following the K-LL dielectronic recombination of initially hydrogen-like ions.Calculation is carried out within the framework of the density matrix theory combined with the multiconfiguration Dirac-Fock approach.Attention is paid to magnetic sublevel alignment in the resonant intermediate state and to its nonuniform radiative decay processes.It is shown that the Breit interaction between the incident and target electrons plays a significant role for the alignment of the resonant state and thus causes a substantial change in the x-ray emission characteristic,when compared to the incorporation of only the(non-relativistic)Coulomb interaction.The most prominent difference in alignment parameter is found in the 2s2p_(1/2) J=1 resonant state for a wide range of atomic numbers from 9 to 92.For this resonant state of helium-like ions,the Breit interaction becomes significant for ions with nuclear charge Z~30 already.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11274254,91126007 and 11264033.
文摘Detailed calculations are carried out for the electron-impact excitation cross sections from the ground state to the individual magnetic sublevels of the 1s2s^(2)2p^(3)/2 J=2 excited state of highly-charged beryllium-like ions by using a fully relativistic distorted-wave(RDW)method.The contributions of the Breit interaction to the linear polarization of the 1s2s^(2)2p^(3)/2 J=2→1s22s2 J=0 magnetic quadrupole(M2)line are investigated systematically for the beryllium isoelectronic sequence with 42≤Z≤92.It is found that the Breit interaction depolarizes significantly the linear polarization of the M2 fluorescence radiation and that these depolarization effects increase as the incident electron energy and/or the atomic number is enlarged.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10876028,10847007 and 10964010the Scientific Research Foundation of the Higher Education Institutions of Gansu Province.
文摘The multi-configuration Dirac-Fock method is employed to calculate the energy levels and transition probabilities for the electric dipole allowed (El) and forbidden (M1,E2) lines for the 4s^(2) 4p,4s4p^(2) and 4s^(2) 4d configurations of highly charged Ga-like ions from Z =68-95.The lifetimes of the 4s^(2) 4p^(2) P3/2 level of the ground configuration are also derived.Based on our calculations,it is found that the energy level of the 4s2 4p 2P3/2 is higher than that of the 4s4p24P1/2 for the high-Z Ga-like ions with Z ≥ 74,so as to generate an energy crossing at Z =74.The effect of the energy crossing is important to the calculation of the 4s^(2) 4p^(2) P3/2 level lifetime for Ga-like ions with Z≥ 74.
基金Supported by the National Natural Science Foundation of China under Grant Nos 91126007,10847007,10964010,11064012.
文摘The radiative and Auger decay processes of K-shell ionized Np ions are studied theoretically using the flexible atomic code(FAC).Relativistic effects,Breit interaction,QED corrections and nuclear finite mass and volume effects are considered systematically.The resulting calculated K x-rays and Auger spectra of Np are compared with the measured spectra emitted after the electron-capture(EC)-decay of mass-separated ^(237)Pu.The general consistency between theory and experiment is good;the relative intensities and relative positions of the peaks in the measured spectra are reproduced with good accuracy,in spite of the existence of different ways to produce the primary K-shell vacancy,enabling identification of the observed structure in the experimental spectra.We find that most of the radiative transition rates are greater than the Auger transition rates,and the latter decrease rapidly with the transfer of initial vacancies to the outer shell.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.10774122 and 10876028)the Natural ScienceFoundation of Gansu Province,China(Grant No.1010RJZA014)the Foundation of Northwest Normal University,China(Grant No.NWNU-KJCXGC-03-72)
文摘In this work, the KLL dielectronic recombination （DR） processes of highly charged He-like to O-like xenon ions are studied systematically by using a DR program, which is based on the multi-configuration Dirac-Fock （MCDF） method. The KLL DR resonant energies and the corresponding resonant strengths are calculated, emphasizing especially the effect of the Breit interaction on the DR strengths. The theoretical KLL DR spectra are obtained and compared with the latest experimental results obtained in the Shanghai Electron Beam Ion Trap.
