Evidence for the Formation of a Local Pre-Existing Surface Band-Gap Electronic State by F– Projectile Grazing Scattering from a LiF(001) Surface

The experimental measurement of slow F– ions (v < 0.1 a.u.) scattered from a clean and flat LiF(001) surface at a grazing angle of incidence shows that there is a large fraction of F– projectile destruction. Here, from detailed energy defect and transition probability calculations, we find that the large F– destruction observed was due to the formation of a local pre-existing surface band-gap electronic state, Li2 +(12Σu +,R = a LiF/√2) (a LiF = lattice constant of the LiF crystal), via a nearly resonant charge transfer between the F– projectile and two nearest-neighbor Li+ lattice ions along the ⟨110⟩ or ⟨1̅10⟩ channel at the LiF(001) surface. In combination with the related energy loss, the physical pictures of the producing mechanism of various products for 1 keV F+ incidence based on this state are also presented. An internuclear distance of R = 2.84 Å makes the efficient and controllable preparation of this state on a LiF surface possible, paving the way for atomic-scale microdevice fabrication.