PHOTOIONIZATION OF THE GROUND AND EXCITED-STATES OF NE-LIKE NI-18+

The R-matrix method is used to calculate cross sections for the photoionization of the ground 2p6 1S(e) and first excited 2p(5)3s 3P(o) states of neon-like Ni18+. Configuration interaction wavefunctions are used to represent two target states of Ni19+ ion retained in the R-matrix expansion. The results are obtained in the energy region close to ionization threshold. The cross sections show series of Rydberg states which converge onto the 2S(e) threshold of Ni19+. Most of these resonances are analysed and their positions and widths are given. The partial cross sections for the photoionization of 3P(o) state are also discussed. The calculation is carried out in LS coupling.