Effective collision strengths for optically allowed transitions among degenerate levels of hydrogenic ions with 2⩽Z⩽302⩽Z⩽30

The Coulomb–Born approximation is used to calculate electron-impact excitation collision strengths and effective collision strengths for optically allowed transitions among degenerate fine-structure levels of hydrogenic ions with 2⩽Z⩽302⩽Z⩽30 and n⩽5n⩽5. Collision strengths are calculated over a wide range of energies up to Ej/Z2=10Ryd. Effective collision strengths are obtained over a wide temperature range up to 108K by integrating the collision strengths over a Maxwellian distribution of electron velocities.