Neutralization of energetic light ions at a solid surface

Abstract

We test the theoretical model that the electron capture of proton takes place at a solid surface by Coulomb interaction between electrons in solid and the proton in vacuum. If a thin target is tilted relative to the incident beam, the charge state distribution of the transmitted ions is expected to change mainly due to the change in the time of interaction. This change is not observed for 200 keV H-atoms and 700 keV He⁺-ions transmitted through carbon and gold foils for tilt angles up to 60° relative to the incident beam direction. Furthermore, a numerical calculation shows that the electron capture probability based on the model is small compared with the observed value. These results suggest that the model is inadequate for proton neutralization.