Electron impact excitation -autoionization of the (2s2)1S and (2s2p)3P states of helium

Abstract

Measurements have been made of the ejected-electron spectra arising from the autoionization of the (2s2)1S and (2s2p)3P states of helium by incident electrons having energies of 70, 80, 100 and 200 eV and for ejected-electron angles in the range 40-130'. The asymmetric lineshapes observed in the spectra are parametrized using the method proposed by Shore and Balashov. The parameters show a sensitive dependence on the kinematics and dynamics of the process. Comparison is made with previous experimental data and with first-order calculations.