Electron collisional excitation of beryllium-like ions: C²⁺, N³⁺, O⁴⁺and Ne⁶⁺

The Coulomb-Born and Coulomb-Born-Bely approximations have been used to calculate the cross sections of electron impact excitation for six allowed transitions in the beryllium-like ions C 2+ , N 3+ , O 4+ and Ne 6+ . The cross sections have been obtained for electron impact energies from threshold to the high-energy region. The authors find that the Coulomb-Born-Bely calculation gives good results comparable with the distorted-wave calculation.