THE ENERGY SHIFT OF THE BINARY ENCOUNTER ELECTRON PEAK IN ION-ATOM COLLISIONS

The energy shift of the binary encounter electron peak as a function o f projectile charge state and impact energy has been investigated. For (nearly) fully stripped ions at an impact energy of 1.1 MeV amu-1, we found that the shift shows a weak linear increase as a function of ch arge from approximately 93 eV for C4+ to approximately 151 eV for Cl14 + when H-2 is used as a target, whereas these values are 163 eV and 29 5 eV respectively with a He target. Further we found that the shift fo r C6+ + H-2 decreases as a function of impact energy from approximatel y 115 eV at 0.6 MeV amu-1 to approximately 80 eV at 1.8 MeV amu-1. Our findings are well reproduced by the recently developed channel-distor ted Brinkman-Kramers approximation for ionization to the projectile co ntinuum.