Distortion of He Fano lineshapes by strong post-collision interaction in - He collisions

Abstract

The three-body post-collisional interaction (PCI) between the scattered proton, recoil target ion and emitted electron has been investigated by electron spectrometry near the helium resonances, in the 20 - 100 keV energy range ( = 0.9 - 2 au). Particular attention has been paid to the PCI deformations of the Fano lineshapes when . Their angle and collision velocity dependences have been studied for the first time experimentally. A large variety of lineshapes has been observed, all of them being successfully described by a single formula. At the lowest proton velocities the rescattering effect (also called Coulomb two-path scattering) is seen.