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 1s(2)2s(2)S ground-state of C IV. For low photon energies, corresponding solely to the 2s photoionization cr oss section, good agreement is found with previous calculations. For h igher photon energies, permitting inner-shell photoionization of the 1 s electron, much more resonance structure is found than in previous st udies, due to the more comprehensive consideration of the states of th e C V target. A recent experiment has measured the K-shell photoioniza tion cross section, and the data are in reasonable accord with the pre sent results. Individual cross sections corresponding to the C V ion b eing left in specific individual states (direct and conjugate shake-up processes) are also presented for the first time.