Theoretical Investigation of Decay Process in a Doubly Excited 2s^{2 1}S₀ State of He-Like Ions

In the framework of multi-configuration Dirac--Fock theory, a detailed calculation is performed for the decay rates and the energies 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 in moderate and high Z regimes. For heavy ions with Z≥72, the contribution of 2s^{2 1}S₀-1s2s ³S₁ M1 transition is significant. The Breit interaction considerably enhances the 2s^{2 1}S₀-1s ²2S_1/2 Auger rate at high Z regime.