Effects of relativity and configuration interaction onL-shell Auger and radiative decays of the doubly excited 3l3l’ states of sodiumlike ions

Auger and radiative transition energies and rates for the states from the 2$p^5$3l3l’ and 2s2$p^6$3l3l’ configurations of the Na-like ions have been calculated for 18 ions with atomic number 18≤Z≤92 using the multiconfiguration Dirac-Fock method. The Z dependence of the transition rates for a few selected states has been analyzed. Numerous irregularities are present in many transitions due to the level-crossing interaction. The effects of relativity and configuration interaction are simultaneously important for medium and heavy ions. These effects can sometimes change the rates for weak transitions by orders of magnitude. Strong configuration interaction between states from the 2$p^5$3$p^2$ and 2$p^5$3s3d configurations has been found. Inclusion of the Breit interaction in calculations of the Auger matrix elements can change the Auger rates by as much as a factor of 2. The spin-orbit mixing and Breit interaction are responsible for the decay of most of the quartet states. In particular, the 2$p^5$3s3$p^4$ $D_{7/2}$ metastable state of low-Z ions decays predominantly by Auger-electron emission via the magnetic interaction.