Theoretical Research On The Transitions Among The Levels And Oscillator Strength Of 1s²np-1s²n'd For Co²⁴+ Ion

In this paper, the present status of the development for atomic and molecular physics and the importance of highly charged ions are briefly introduced and the achievement of theoretical study is elaborated. The essential points of full core plus correlation (FCPC) method are described. This method is further expanded to calculate the non-relativistic energies of 1s2nl(l=p,d.n≤9) states for lithium-like Co24+ion with higher nuclear charge. In order to improve the accuracy of theoretical results, the contributions from higher angular momentum partial wave and the core-correction are involved. The corrections to the energy of these states from relativistic and mass-polarization effects are calculated by using the first-order perturbation theory. Under a hydrogenic approximation, the corrections from higher-order relativistic and quantum electrodynamics (QED) effects are also estimated. The ionization energy, excitation energy and transition energy are obtained. In the calculation of the fine structure splitting for these states, we not only take into account the spin-orbit and spin-other-orbit interactions, but also estimate the QED and higher-order relativistic contributions. Based on single-channel quantum defect theory, the quantum defects of 1s2nl (l=p,d) Rydberg series for Co24+ ion are determined. By using these quantum defects as input, a semi-empirical approach is used to calculate the ionization energies. The results are coincided well with that of the FCPC method. The energies of any high-excited states (n≥10) can reliably be predicted. Finally, the oscillator strengths of 1s2np-1s2n'd (n≤9) for Co24+ ion are calculated. The results agree well with the experimental data available in the literature. With the quantum defect theory, the oscillator strengths are accurately extrapolated to the entire energy region including the continuum states.