Orbital angular momentum exchange in post-collision interaction

Abstract
The authors have measured the angular distribution of electrons ejected by the He**(2s2)1S autoionising state after its electron impact excitation via the He-(2s2p2)2D resonance. Taking into account interference with electrons from the direct ionisation of helium, analysis of this angular distribution provides evidence for angular momentum exchange between ejected and scattered electrons during the post-collision interaction.