The study of photoionization of neon-like Ar IX

The photoionization of the ground state of neon-like is investigated and the autoionizing spectrum of 2s22p52P1/2ns,nd and 2s2p62S1/2np Rydberg series of Ar IX are studied by using the Breit–Pauli Hamiltonian within the R-matrix theory combine with the QB method of Quigly–Berrington [L. Quigley, K.A. Berrington, J. Pelan, Comput. Phys. Commun. 144 (1998) 225]. We predict the energies and widths of four Rydberg series of Ar IX.