Differential cross sections for charge transfer and excitation in low-energy Be⁺-He, Ne collisions

Differential cross sections for charge transfer and excitation in low-energy (2-5 keV)Be + -He, Ne collision systems have been measured. For both collision systems, excitation of the Be + ion to the 2p state is found to be the dominant inelastic process in soft collisions (reduced angle below 10 keV deg), whereas charge transfer and target excitation are the main processes in violent collisions. In the Be + -Ne case, the Be + 2p excitation probability shows an oscillatory structure which is interpreted within a simple two-state model of the collision. The charge-transfer and target-excitation processes are discussed in terms of the electron-promotion model.