Thermalized-positron induced ion-desorption from surfaces

A system of slow-positron-induced desorption spectroscopy has been constructed and applied to proton desorption from polycrystalline Ni surfaces. The cross section for the ion desorption at a positron incident energy of 1.9 keV is more than two orders of magnitude larger than that by electron-stimulated desorption with the similar incident energies. The results suggest that ion-desorption is caused by the thermalized positrons coming back from the bulk to the surface.