It was found that protons and deuterons could be efficiently removed from monocrystals during electron irradiation in vacuum at temperatures which were close to ambient. On the other hand, irradiation in air produced no appreciable change in the concentration of hydrogenic species. It was concluded that these results unambiguously demonstrated the difference between irradiations in vacuum and air. However, it was unclear how the presence of air retarded the out-diffusion of protons and deuterons.

R.Gonzalez, E.R.Hodgson, C.Ballesteros, Y.Chen: Physical Review Letters, 1991, 67[15], 2057-9