Electron impact excitation of the ground state of CV and Mg XI to the 23S and 23P0states

The R-matrix method with eleven target states is used to calculate effective collision strengths for electron excitation of the 23S and 23P0 states of C V and Mg XI. For C V the results of the present calculations are in good agreement with the earlier distorted-wave calculations of Pradhan et al. (1981) over a wide temperature range and confirm the importance of resonance effects particularly for the 11S-23S transition. Resonance effects also contribute significantly to excitation of the 23S state of Mg XI; however, for this ion the results are significantly lower than those of Pradhan et al.