Electron-ion collisional ionization cross sections and rates for the Ne isoelectronic sequence

In this paper, we present electron impact ionization cross sections for six Ne-like ions in the range 22 less than or equal to Z less than or equal to 39 calculated by means of a distorted-wave Born exchange approximation met hod including a relativistic correction. Direct ionization from the ground (n = 2) and excited (n = 3-5) states are calculated. A systematic study of the dependence of the cross section on impact energy and nuclear charge is carried out for all states. The results of the calculations are fitted by e mpirical formulas to meet the requirements of applications; the fitted valu es are found to be in good agreement with the calculated results. An empiri cal formula with high accuracy for calculating ionization rates is also giv en. (C) 1998 Academic Press.