Excitation cross sections of the n = 3 states of helium at incident electron energies near autoionizing levels

Excitation cross sections have been obtained for the 31P, 31S and 33S states of helium at incident energies near 60 eV. All three cross sections contain structures at energies close to the (2p2)1D and (2s2p)1P autoionizing levels. The magnitudes, positions and shapes of these structures are discussed in terms of possible post-collision interaction and resonance mechanisms.