ENERGY SHIFTS OF BINARY-ENCOUNTER ELECTRON PEAKS IN ION ATOM COLLISIONS

The so-called binary-encounter electron peak resulting from collisions between quasifree target electrons and energetic projectile ions is studied. The shift in energy of the binary-encounter electron peak relative to the energy of scattered free electrons at rest is measured as a function of scattering angle in collisions between 1 and 1.5 MeV amu-1 C(q+) (q=4,5 and 6) and H-2 and He. The measured shifts are in good agreement with theoretical results based on the continuum distorted wave eikonal initial state (CDW-EIS) approximation. Both theory and data show an increase of the shifts with projectile charge state and scattering angle. For observation angles larger than 30-degrees, the experimental shifts rise faster than theory.