Total cross-section for electron impact excitation of the resonance levels in Li, Na and K are calculated using the method due to Crothers and McCarroll. The results are compared with other available theoretical and experimental data.

The effect of including distortion (with and without exchange) in the wavefunction for the continuum electron while calculating the probability of autoionization of 2s²¹S. 2s2p^1,3P, 2p²¹D and 2p²¹S states of He and Li⁺ has been studied.

Coulomb-projected Born methods for the theoretical study of electron impact excitation of hydrogen and helium are reviewed. The results obtained by using different forms of Coulomb-projected Born methods are compared with other theoretical and experimental results and analyzed. The inadequacy of the variable charge Coulomb-projected Born approximation (VCCPB)—the most recent form of the Coulomb-projected Born methods—in giving good results in processes where exchange is dominant is discussed in detail. The ‘modified’ VCCPB approximation obtained by modifying the VCCPB method to remove its shortcomings is also discussed and its application to electron impact excitation of 2³s state of helium is studied.

The modified variable-charge Coulomb-projected Born approximation is applied to electron impact excitation of 1¹S–2¹S transition in helium. The results are compared with other theoretical and experimental results.