ON THE ASYMPTOTIC-BEHAVIOR OF ELECTRON-IMPACT IONIZATION CROSS-SECTIONS

Behavior of the ionization cross sections at high incident electron energies E >> I was considered, where I is the binding energy of the target. Presenting the total ionization cross section as a sum of the classical and dipole (Bethe), terms the dependences of the ionization cross sections on the principal and orbital quantum numbers of the target are investigated. The applicability of the asymptotic formulas obtained is discussed on the basis of comparison with ionization cross sections calculated in the Born approximation for high n states.