Characteristic velocity for inner-shell charge exchange of low energy Ne ions scattered from a polycrystalline Ni surface

The threshold energy of charge exchange processes involving inner-shell electron promotion is investigated in the case of low collision energy Ne ions scattered from a polycrystalline nickel surface. Two distributions of charge fractions are measured from time-of-flight spectra at constant perpendicular velocity in the outgoing path. The energy distribution (energy = 2–12 keV, constant scattering angle = 12°) and the angular distribution (scattering angle = 7–50°, constant energy E = 4 keV) allow the crossing distance RC for electronic transitions during the close-encounter to be determined. Using the value of RC in statistical distributions of close collisions coupled with the Landau–Zener model, we obtain the characteristic velocity VC of the crossing point in the Ne/Ni system.