**Table 5.** The 2s*n*p threshold energy (*E*_{limit}) and quantum defect δ of ^{3}P_{1} and ^{1}P_{1} states of Ar^{8+}, Fe^{16+}, Kr^{26+} and Xe^{44+} ions.

**Abstract**

Photoionization (PI) cross sections of the ground state 1s^{2} 2s^{2} 2p^{6}^{1} S_{0} of Ne-like Ar^{8+}, Fe^{16+}, Kr^{26+} and Xe^{44+} ions are calculated by using the Dirac atomic *R*-matrix code based on a fully relativistic *R*-matrix method. To analyze the detailed resonant structure, systematical calculations based on the multiconfiguration Dirac–Fock method are performed for the dominant 2s → *n*p resonant transitions, and the resonant energies, strengths and total natural widths are presented. The resonant structures and characteristics of the PI cross sections and resonance strengths along the Ne-like sequence are discussed with emphasis on the influence of relativistic effects. For the Ar^{8+} ion, good agreement is found between the present results and available theoretical calculations and experimental data.