Angular distributions of the atomic scandium 3d and 4s photoelectrons in the region of the 3p⃗3d giant resonance

A determination of the angular distribution parameter β of the 3d and 4s main lines of atomic scandium in the resonance region of the 3p⃗nd,ms excitations has been carried out using electron spectrometry in conjunction with monochromatized synchrotron radiation. These measurements reveal strong variations of β throughout the entire resonance region, highlighting the complicated nature of the ionization process for this first and seemingly simple 3d transition metal. The β values of the photoelectrons resulting in 4s subshell ionization deviate significantly from 2.0 in qualitative, but not quantitative, agreement with recent many-body perturbation-theory calculations.