C Z Dong

Theoretical Auger and photoionization studies for open-shell atoms and ions

Abstract In the last few years, the R atip package has been found useful for studying the properties of atoms and (highly charged) ions within rather arbitrary configurations. Here, the latest extensions to this code are reviewed which help calculate several Auger and photoionization parameters, including cross sections, angular coefficients as well as correlation functions for the emitted electrons. In addition, a number of recent case studies on the electron spectra of resonantly excited noble gases and open-shell atoms are briefly summarized.

The excitation energies, ionization potentials, and oscillator strengths of neutral and ionized species of Uuq (Z=114) and the homolog elements Ge, Sn, and Pb

Multiconfiguration Dirac-Fock method is employed to calculate the excitation energies, ionization potentials, oscillator strengths, and radii for all neutral and up to four times ionized species of element Uuq, as well as the homolog elements Ge, Sn, and Pb. Using an extrapolative scheme, improved ionization potentials of Uuq were obtained with an uncertainty of less than 2000 cm(-1). Two relatively stronger resonance transitions are predicted for the element Uuq. In particular, the strongest line in Uuq, corresponding to the [6d(10)7s(2)7p(3/2)8s(1/2)](1)-->[6d(10)7s(2)7p(3/2)(2)](2) transition at 22 343 cm(-1), just lies in the prime energy region of experimental measurement.

Energy levels and transition probabilities for possible X-ray laser lines of highly charged Ni-like ions

Abstract The 45 low-lying energy levels and the transition probabilities among these levels connected with possible X-ray laser lines are calculated for Ni-like ions from Z=74 to 84. In the calculations, main correlation, relaxation and relativistic effects are considered. The calculated energy levels and transition probabilities are compared with some experimental and theoretical results. Finally, the contributions of lots of weak correlations on the transition wavelengths and probabilities are discussed by including partly single and double excitations from the 3l inner-shells into the 4l and 5l orbital layers.

The theoretical studies on the electron-impact single ionization of Se3+

We have performed fully relatively level-to-level distorted-wave (LLDW) calculations for both direct ionization (DI) and excitation autoionization (EA) of ground state Se3+ ion using the flexible atomic code (FAC). Large EA contributions come from the excitations 4p to nl and 3d to nl. Our calculated total DI+EA cross section have been compared with the recent experimental results. It suggests that the contributions of resonace-excitation double-autoionization process (REDA) to electron impact single ionization of Se3+ at the near threshold are more than 25%.

Alignment of the excited states and angular distribution of subsequent decay following the radiative electron capture into lithium-like ions

The radiative electron capture into highly charged lithium-like U89+ ions is studied in the framework of the density matrix, based on Diracs equation. Emphasis is placed on the population of 1s22s2p3/2 J=1,2 excited states, as well as the angular distribution and polarization of subsequent characteristic photon emissions (included E1 and M2 transition).

Photoionization of the ground 3s2 1S0 and excited 3s3p 3P2,1,0 states of Fe XV

The near-threshold photoionization cross sections of the ground 3s2 1S0 and excited 3s3p 3P2,1,0 states of Fe XV ion are investigated using the fully relativistic R-matrix method. The dominant resonances are analyzed and identified. The present results are compared with early theoretical values available in the literature.

Systematic study of the K x-ray spectra for hollow Kr and Xe atoms

In this work, the satellite and hypersatellite x-rays resulted from additional 1-7 holes in L-shell for Kr and Xe atoms have been calculated systematically by using the multiconfiguration-Dirac-Fock(MCDF) method. The present calculations are in good agreement with the latest experiment at the HIRFL-CSR in Lanzhou.

Linear polarization of x-rays emitted in the decay of highly-charged ions via overlapping resonances

The linear polarization of x-rays, emitted from highly-charged ions, has been studied within the framework of the density matrix theory and the multiconfiguration Dirac-Fock method. Emphasis was placed especially on two-photon cascades that proceed via intermediate overlapping resonances. For such two-step cascades, we here explore how the level-splitting of the resonances affects the linear polarization of the x-rays, and whether modifications in the degree of polarization may help determine small level-splittings in multiply- and highly-charged ions, if carefully analyzed along isoelectronic sequences. Detailed calculations are carried out for the 1s2p2 Ji = 3/2 → 1s2s2p J = 1/2, 3/2 + γ1 → 1s22s Jf = 1/2 + γ1 + γ2 radiative cascade of lithium-like W71+ ions. For this cascade, a quite remarkable increase of the (degree of) linear polarization is found for the second-step γ2 photons, if the level-splitting becomes smaller than Δω 0.2 a.u. ≈ 5.4 eV. Accurate polarization measurements of x-rays may therefore be also utilized in the future to ascertain small level-splittings in multiply- and highly-charged ions.

Theoretical study of inner-shell electron-impact excitation of highly charged ions: Alignment and angular distribution of electron emission

The influence of the Breit interaction, typically appears as a relativistic correction to the Coulomb repulsion acting among the electrons, on the alignment (i.e. the population of the magnetic sublevels) and the angular distribution of electron emission from the excited state have been investigated systematically. Detailed calculations have been carried out for the electron-impact excitation cross sections from the ground state to the individual magnetic sublevels of highly charged beryllium-like ions by using a fully relativistic distorted-wave (RDW) method. A remarkable change in the alignment and the electron angular distribution due to the Breit interaction is found, especially for the cases with high-energetic incident electron and high-Z target ions.

Photoionization cross section of Fe7+ ion

The fully relativistic R-matrix calculation is performed for the photoionization cross section of Fe7+. The results are compared with available experimental spectrum and previous calculations of the cross section.