We report the energy and angular distribution of ejected electrons from CH4 and H2O molecules impacted by 1 MeV H+, He+, and 650 keV N+ ions. Spectra were measured at different observation angles, from 2 to 2000 eV. The obtained absolute double-differential electron-emission cross sections (DDCSs) were compared with the results of classical trajectory Monte Carlo (CTMC) and continuum distorted wave, eikonal initial state (CDW-EIS) calculations. For the bare H+ projectile both theories show remarkable agreement with the experiment at all observed angles and energies. The CTMC results are in similarly good agreement with the DDCS spectra obtained for impact by dressed He+ and N+ ions, where screening effects and electron loss from the projectile gain importance. The CDW-EIS calculations slightly overestimate the electron loss for 1 MeV He+ impact, and overestimate both the target and projectile ionization at low emitted electron energies for 650 keV N+ impact. The contribution of multiple electron scattering by the projectile and target centers (Fermi shuttle) dominates the N+-impact spectra at higher electron energies, and it is well reproduced by the nonperturbative CTMC calculations. The contributions of different processes in medium-velocity collisions of dressed ions with molecules are determined.
|Journal||Physical Review A - Atomic, Molecular, and Optical Physics|
|Publication status||Published - Jul 20 2016|
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics