Impact-parameter dependence of resonant-coherent excitation of channeled ions

The resonant-coherent excitation of channeled hydrogenic ions is theoretically investigated. The crystal potential averaged over the ion trajectory, together with the induced wake potential, produces mixing of its electronic states and shifting of its energy levels. This effect introduces a dependence of the resonance on the position of the ion. The periodic components of the crystal potential are responsible for the excitation. Schrodinger's equation is numerically solved to illustrate the way in which the excitation takes place. An electron promoted to an excited state is shown to evolve non-adiabatically, retaining most of its initial character while the ion travels across long distances in the channel.