EXCITATION OF HELIUM BY PROTONS AND ELECTRONS

Generalized oscillator strengths and cross sections for excitation of helium by protons and electrons have been calculated using Born approximation. Transitions from the ground state to all n = 2, 3, 4 singlet states have been considered, including some sub-state transitions. Three types of ground state wave functions have been employed: the one-parameter Hylleraas function, an exponential fit to the Hartree-Fock function, and a variationally determined Eckart function. The final states are linear combinations of products of hydrogenic wave functions. It is shown that the different wave function combinations give rise to largely different excitation functions, but that the combination with HF gives, except for n1S, results that complete favourable with results obtained using much more accurate wave function combinations. © 1969.