Relativistic Theoretical Study On The Structure And Decay Processes Of Excited States In Innershell Of Atoms

A systematic theoretical study on the level structures, decay process and related atomic process of Li-like and He-like ions have been carried out by using Multiconfigura-tion Dirac-Fock (MCDF) method and two new components REOS99 and Auger of RATIP package, in which the effects of relaxation and correlation were considered systematically.At first, based on the MCDF method, a new program was developed for calculation of cross sections of dielectronic recombination (DR). As an example, the decay rates and the corresponding DR cross sections have been systematically calculated for the double excited states of C³⁺, Ar¹⁵⁺, Kr³³⁺ and U⁸⁹⁺ ions. For C⁴⁺, Ar¹⁶⁺ and Kr³⁴⁺ ions, a good agreement has been found between the present calculations and the previous theoretical and experimental results; for U⁹⁰⁺ ion, the effect of the Breit interaction on the DR cross sections has been emphasized especially.Secondly, by considering the effects of relativity, electron correlation and quantum electrodynamic (QED) systematically, the study has been carried out for the decay process of the Is2s^{2 2}S_1/2 state of Li-like ions. It is found that the decay properties of these states are quite different along the isoelectronic sequence: for low Z ions up to Z = 30, the Auger decay channel is dominant; for medium Z ions up to Z = 80, a two-electron one-photon radiative decay caused by a strong electron correlation becomes a competitive channel; and for very heavy ions about Z = 90, the magnetic dipole radiative decay becomes important too. In addition, the QED contributions to the excitation energy and the contributions from the Breit interaction to the Auger decay rates are stressed for heavy ions in particular.Finally, the detailed study has been performed for the decay behavior of the doubly excited 2s^{2 1}S₀ state of He-like ions, of which atomic number Z ranges from 6 to 92. The 2s^{2 1}S₀—1s ²S_1/2 Auger decay is predominant at low Z regime, whereas the 2s^{2 1}S₀—1s2p ^1,3P₁ two-electron one-photon transitions become quite important at moderate and high Z regime. For heavy ions with Z≥72, the contribution of 2s^{2 1}S₀—1s2s ³S₁ Ml transition is significant. The Breit interaction considerably enhances the 2s^{2 1}S₀—1s ²S_1/2 Auger rate at high Z regime.