Energy and angular distributions of the low-energy electron emission in collisions of 4 MeV/u bare F ions with He atoms

Abstract

The energy and angular distributions of double-differential cross sections (DDCS) of electron emission from He in collisions with 4 MeV/u F^{9 +} ions are reported. The derived single-differential distributions and the total cross sections are also reported. The measured distributions of the low-energy electrons between 1 and 400 eV over a wide angular range between 20° and 160° are compared with the state-of-the-art quantum mechanical models. The first Born (B1) and the continuum distorted wave-eikonal initial state (CDW-EIS) approximations are used for this purpose. The DDCS for a given angle was found to fall by a few orders of magnitude over the electron energy range studied. The CDW-EIS model provides excellent agreement with the energy distributions and the angular distributions. The electron energy dependence of the forward?backward asymmetry parameter shows monotonically increasing behaviour. This has been explained very well in terms of the CDW-EIS model, which includes the two-centre effect. A large deviation from the B1 is also observed. We have also derived the single-differential distributions in terms of the angle as well as the electron energy. These distributions are also well reproduced by the CDW-EIS model.