Ionization of atoms and molecules using 200-keV protons and 5.5-MeV/u bare C ions: Energy-dependent collision dynamics

BHOGALE, A.; BHATTACHARJEE, S.; TRIBEDI, LOKESH C.; MANDAL, A.; BAGDIA, C.; RIVAROLA, R. D.; ROY CHOWDHURY, MADHUSREE; BANSAL, H.; MONTI, J. M.

Physical Review A

American Physical Society

Año: 2020 vol. 102

2469-9926

Using electron spectroscopy technique, we measure the absolute double-differential cross sections (DDCSs)of electrons emitted in collisions of 200-keV protons on He, CH4,andO2and 5.5-MeV/u bare C ionscolliding on O2. The emitted electrons are measured in the energy range from 1 to 400 eV for He and CH4targets and up to 600 eV for O2to include theK-LLAuger line of oxygen. The electrons are detected overdifferent emission angles varying from 20◦in the extreme forward direction to 160◦in the backward direction.The single-differential cross section (SDCS) and total cross section are deduced from the measured DDCSsspectra for all the targets. The DDCS and SDCS are compared with the state-of-the-art continuum distortedwave?eikonal initial state (CDW-EIS) theoretical model. The CDW-EIS model provides excellent agreementwith the oxygen data at MeV energy, whereas the deviation in the case of keV energy is substantial, in spite ofhaving nearly the same perturbation strength. The forward-backward angular asymmetry shows a saturationeffect in the case of keV energy protons but no such signature is observed for the high-energy collision.A systematic analysis reveals that the asymmetry at low electron energy is sensitive to the associated atomicor molecular structure and is in close agreement with the theory.