High resolution studies of electron excitation

Excitation and polarization functions are presented for the n = 3 states of helium for energies between threshold and the ionization potential. In the case of the line at 501.6 nm (3 1P-2 1S) the present polarization data is affected by the imprisonment of resonance radiation, but in the other cases the data is consistent with threshold values predicted in conservation and angular momentum. The excitation and polarization functions show considerable structure and two of the major features which appear in all the functions as S and P resonances are identified. (author)