Photoionization of atomic magnesium including double-electron resonances

The photoionization cross sections of the 2$s^2$, 2$p^6$, and 3$s^2$ subshells of atomic magnesium and angular distribution asymmetry parameters for the 2$p^6$ subshell have been calculated using many-body perturbation theory. Double-electron resonance structure near the 3s threshold has been included. At higher energies, resonance structures due to the 2s→np and 2p→nd(ms) (n>=3, m≥4) excitations have also been included. The effects of spin-orbit interactions on the 2p→nd(ms) resonances are examined. The calculated asymmetry parameter for the 2$p^6$ subshell including the 2s→np resonance structure is compared with the calculations of Deshmukh and Manson [Phys. Rev. A 28, 209 (1983)].