Generalized oscillator strengths for the ionization of atomic helium

Abstract

The first Born approximation is used to calculate generalized oscillator strengths for the single ionization of atomic helium. Wave functions described by Bell and Kingston are employed to calculate both the length and velocity formulations of the Born matrix elements. Reasonable agreement is obtained with the available experimental data in the non-resonant energy loss region. Comparison of theory and experiment near the first ¹P⁰ resonance in helium indicates that it may be possible to derive the resonance parameters using only first Born calculations together with accurate experimental data for three energy loss values at any angle of scattering.