Electron-ion collisional ionization cross sections for the Li isoelectronic sequence

In this work, the authors calculate the electron impact ionization cross sections for Li-like isoelectronic-sequence ions in the range 6 ≤ Z ≤ 29 by means of a distorted-wave Born exchange approximation method including a relativistic correction. The total cross sections include the contributions from direct ionization and excitation autoionization. For excitation autoionization the branching ratio and the configuration interaction are considered. A package of computer codes has been developed and used to calculate these cross sections. Systematic study of the dependence of the cross sections on impact energies and nuclear charges is carried out. The results of the calculations are fitted by empirical formulas to meet the requirements of applications. The fitted values are in good agreement with the calculated results. 26 refs., 4 figs., 11 tabs