Transfer ionization and total electron emission for 100 keV amu-1 He2+ colliding on He and H2

We have measured electron emission for transfer ionization (TI) and total electron emission (TEE, all emission processes) for 100 keV amu-1 He2+ on He and H2 targets. Double differential cross sections have been obtained for emission angles θ = 0 deg., 20 deg. and 45 deg., and electron energies ranging from 2 to 300 eV. Pure ionization, mainly due to single ionization, dominates the low-energy electron emission. The main observed structure in the electron spectra, a cusp centred at θ = 0 deg. and at a speed equal to that of the incident projectile, presents an asymmetric shape. This is in contrast to the symmetric shape observed by us at 25 keV amu-1 for the same collision systems, suggesting a change in the cusp formation mechanism for TI within this energy range