Apparent change of the 3C/3D line intensity ratio in neonlike ions

The resonance 3C ([(2p(5))(1/2)3d(3/2)](J=1)->[2p(6)](J=0)) to intercombination 3D ([(2p(5))(3/2) 3d(5/2)](J=1)->[2p(6)](J=0)) line intensity ratio of neonlike ions has been studied. The measured line intensity ratio for neonlike Xe44+ ions shows an apparent change, which is reproduced by the calculations using the relativistic configuration interaction plus many-body perturbation theory. It is clearly elucidated that the change in the 3C/3D line intensity ratio is caused by strong configuration mixing between the upper levels of the 3D and 3F ([(2p(5))(1/2)3s](J=1)->[2p(6)](J=0)) lines. The present measurement allows us to discuss the 3C/3D line intensity ratio for the highest-Z ions hitherto, which suggests that the experiment-theory discrepancy in the 3C/3D line intensity ratio of neonlike ions diminishes with increasing atomic number Z and further trends to vanish at higher-Z ions. Furthermore, the present study provides benefits to better understand configuration mixing effect in the radiative opacity of hot plasmas. (C) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement