Photoionization of Ar VIII

•The photoionization cross sections of Ar VIII are investigated.•It contains the excitation of 2s, 2p and 3s electron.•The energy levels and widths of 22 series of Ar VIII have been calculated.

The photoionization cross section, energy levels and widths of 22 Rydberg series (in the autoionization region) for Na-like Ar VIII were investigated by using of R-matrix method. The relativistic distorted-wave method is used to calculate the radial functions, and QB method of Quigly–Berrington [Quigley et al. 1998] is employed to calculate the resonance levels and widths. We have identified the formant in the figure of the photoionization cross section.