Knowledge Bank

Close-coupling calculations using the R-matrix method have been carried out for the photoionization cross sections of carbonlike ions: F^3+, Ne^4+ , Na^5+, Mg^6+, Al^7+, Si^8+, S^10+, Ar^12+, Ca^14+, and Fe^20+, which are of interest in the calculation of plasma opacities. This is an extension of previous work for radiative data for the C sequence. Detailed results including extensive structures due to autoionizing resonances are presented for the ground states; however, the calculations have also been carried out for a large number of excited bound states of each ion and their features are discussed. The partial photoionization cross sections of the ground state into excited states of the residual ion are obtained. The effect of resonances on the branching ratios of partial cross sections at excited thresholds is discussed. Interesting features related to the Z dependence of the ground-state photoionization cross sections of all ions in the C sequence are discussed.