Total and partial generalized oscillator strengths for transitions to the continuum of helium

Abstract

The generalized oscillator strengths (GOS) for transitions to the continuum of helium between the second and third thresholds of ionization of helium by fast electrons are calculated. The total and partial GOS, the GOS ratios in the ionization of helium to the n = 1 and n = 2 states of the He+ residual ion, the parameters of the autoionized states converging to the threshold n = 3 in the total and partial GOS and the dependence of the spectroscopic characteristics of the resonances on momentum transfer are determined. The ground state of helium is described by a many-parameter wavefunction. The continuum of helium between the second and third thresholds is described with allowance for the coupling among 20 configurations, which correspond to the two-electron excitations and four configurations with the free electron above the n = 1 and n = 2 states of the He+ ion.