Photoionization of some neutral atoms and their ions

Calculations of photoionization cross sections relative to the 2p subshell have been carried out for the following atoms: Ne, Na, Mg and Al and their ions, and to the 3p subshell for the neutral atoms Ar, K, Ca and Sc and some of their ions. The ground state of the most ionized elements involves the 1s 2 2s 2 2p and 1s 2 2s 2 2p 6 3s 2 3p configurations. The evolution of the behaviour of the cross sections as the degree of ionization increases and a comparison of these results with others are emphasized. To remedy the failure, in some instances, of a central potential (relative to the ground state) model for neutral atoms and weakly ionized elements an alternative central potential calculated from a spectroscopic criterion and the close-coupling approximation (3p 6 and 3p 5 configurations) has been used.