Resonant (RTE) and Non Resonant (NTE) Transfer Excitation in 4 MeV B4+ collisions with H2, He and Ar studied by zero‐degree Auger projectile electron spectroscopy

It is well known that for very asymmetric collisions between a highly charged ion and H-2 near the RTE resonance, NTE is practically negligible. However, even though the interplay between RTE and NTE and their possible interference has been addressed formally and more recently by concrete calculations, experimentally very little work has been done on fast collision systems of increasing symmetry. We report on recent Auger electron RTE/NTE double differential cross section measurements of H-like B4+ ions in 4 MeV collisions with H-2, He and Ar gas targets. Calculations using an atomic orbital close coupling (AOCC) method indicate NTE to be negligible for B4+ collisions with H-2, but possibly substantial (depending on screening considerations) for He and Ar targets. R-matrix calculations are also presented for elastic (resonant and non-resonant) electron scattering from B4+. Within the electron scattering model (ESM), the active target electron can be considered to scatter as a free particle with a momentum distribution governed by its Compton profile. Thus, a single R-matrix calculation combined with the individual momentum distribution of each target should be sufficient to describe the RTE process. While this is found to be the case for H-2 and He, results for Ar are not in such good agreement, even allowing for the possibility of destructive RTE-NTE interference.