A unified treatment of Penning ionization and excitation transfer

It is shown how Penning ionization (A+B→A+B++e−) and excitation transfer (A+B→A+B,B=Rydberg state) can be described by essentially the same theoretical model. The physical basis of this is that in both cases the final state of species B consists of an ion core B+ with a highly excited electron, and whether the electron is slightly bound (B) or slightly unbound (B++e−) matters little to the collision dynamics. The system He(2 3S)+F is analyzed as an example of this theory.