Bulk plasmon induced ion neutralization near metal surfaces

A novel mechanism is proposed for ion neutralization near metal surfaces, whereby a bulk plasmon is emitted during the electron capture, induced by the presence of the external ion which does not penetrate the metal. In a semiclassical picture of this mechanism the electrons increase their velocity in the field of the ion until they surpass the threshold velocity for collective excitation, emitting the plasmon and getting bound to the ion.Primary evaluations of bulk plasmon transition rates for He⁺ interacting with Al surfaces indicate that very close to the image plane the bulk collective channel might become more efficient than the surface plasmon mode to neutralize the ion.