K-shell photoionization cross section of Carbon IV

An 11-state R-matrix calculation is performed to obtain cross sections for the photoionization of the ground-state of C IV. For low photon energies, corresponding solely to the 2s photoionization cross section, good agreement is found with previous calculations. For higher photon energies, permitting inner-shell photoionization of the 1s electron, much more resonance structure is found than in previous studies, due to the more comprehensive consideration of the states of the C V target. A recent experiment has measured the K-shell photoionization cross section, and the data are in reasonable accord with the present results. Individual cross sections corresponding to the C V ion being left in specific individual states (direct and conjugate shake-up processes) are also presented for the first time.