Simultaneous excitation-ionization of helium to the state

Abstract

Simultaneous excitation-ionization of helium to the ionic state by electron impact is studied experimentally and theoretically. Electron-photon angular correlations measured at an incident electron energy of 200 eV and electron scattering angles between and are in reasonable agreement with theoretical predictions. The double-differential cross section shows structure due to interference effects arising from autoionization states decaying into this channel. The emission cross section from threshold to 300 eV is also reported and compared with previous data.