Absolute Cross Sections for Near-Threshold Electron-Impact Excitation of the 2s ²S→2p ²P Transition of Li-Like C³⁺, N⁴⁺, and O⁵⁺ Ions

Excitation cross sections of 1s²2s ²S_1/2→1s²2p ²P_{1/2, 3/2} transition among the fine-structure levels in Li-like C³⁺, N⁴⁺, and O⁵⁺ ions are calculated for energies of the near-threshold by using the relativistic distorted-wave program REIE06. The target state wavefunctions are calculated by using the Grasp92 code. The continuum orbitals are studied in the distorted-wave approximation, in which the direct and exchange potentials among all the electrons are included. The results of the Li-like C³⁺ ion settle the discrepancy between several previous experiments by using the crossed-beams fluorescence method, in good agreement with the measurements of Savin et al. Moreover, the results in Li-like N⁴⁺, and O⁵⁺ ions are compared with the previous experiments, and a good agreement is obtained.