Deng-Hong Zhang

Theoretical study of the photoionization process of Ne-like Ar, Fe, Kr and Xe ions

Photoionization (PI) cross sections of the ground state 1s2 2s2 2p6 1 S0 of Ne-like Ar8+, Fe16+, Kr26+ and Xe44+ ions are calculated by using the Dirac atomic R-matrix code based on a fully relativistic R-matrix method. To analyze the detailed resonant structure, systematical calculations based on the multiconfiguration Dirac–Fock method are performed for the dominant 2s → np resonant transitions, and the resonant energies, strengths and total natural widths are presented. The resonant structures and characteristics of the PI cross sections and resonance strengths along the Ne-like sequence are discussed with emphasis on the influence of relativistic effects. For the Ar8+ ion, good agreement is found between the present results and available theoretical calculations and experimental data.

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%.

Long-range dispersion interactions between excited states of K and rare-gas atoms

The long-range interaction potential plays an important role in the current research in the field of cold atoms[1-3]. such as Bose-Einstein condensation, ultra-cold collisions, and ultra-cold photo-association spectra. Precisely definition of the interaction potential between alkali metal and rare gas atoms has attracted much interest due to its signification in cold atom physics in recent years. For example, the stability and structure of BoseEinstein condensation (BEC)[1] depend on the sign (and magnitude ) of the scattering length, and the scattering length depends on the precise values of the dispersion constants. The long-range van der Waals dispersion coefficients between two atoms, is one of the more important parts of long-range potential. In this work, the long-range interaction between low-lying states of K and the ground state of rare gas atoms are calculated in JJ coupled states, in which the spin-orbital interactions are included. The energy levels and transition arrays that contribute to the dispersion parameters are computed by using the relativistic semiempirical-core-potential method (RCICP)[4]. The rare gas oscillator strengths distributions are derived by using calculations of rare-gas polarizabilities and dispersion coefficients to tune Hartree-Fock single-particle energies and expectation values [5]. The present dispersion coefficients between the ground state of Ar and low-lying states of K are listed in Table 1 and compared with others available values [5]. The dispersion coefficients between the ground state of K and the ground state of rare gas atoms have been calculated in our previous paper [6]. The present results are in good agreement with the configuration interaction plus core polarization (CICP) results [5].

Magic wavelengths of Ca+ ion for linearly and circularly polarized light

The dynamic dipole polarizabilities of the low-lying states of Ca for linearly and circularly polarized light are calculated by using relativistic configuration interaction plus core polarization (RCICP) approach. The magic wavelengths, at which the two levels of the transitions have the same ac Stark shifts, for 4s-4pj,m and 4s-3dj,m magnetic sublevels transitions are determined. The present magic wavelengths for linearly polarized light agree with the available results excellently. The polarizability for the circularly polarized light has the scalar, vector and tensor components. The dynamic polarizability is different for each of magnetic sublevels of the atomic state. Additional magic wavelengths have been found for the circularly polarized light. We recommend that the measurement of the magic wavelength near 850 nm for 4s−4p 3

Polarizabilities and tune-out wavelengths of the hyperfine ground states ofRb87,85

The static and dynamic polarizabilities, and the tune-out wavelengths of the ground state of Rb and the hyperfine ground states of

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

^{87, 85}

Photoionization cross section of Fe7+ ion

Rb have been calculated by using relativistic configuration interaction plus core polarization(RCICP) approach. It is found that the first primary tune-out wavelengths of the

Magic wavelengths of the Ca+ ion for circularly polarized light

5s_{1/2}, F=1, 2

Theoretical study of the dielectronic recombination process of Li-like Xe51+ ions

states of

Long-range dispersion interactions between Li and rare-gas atoms

^{87}