Experimental indications of the ion channeling effect above the solid surface

The work have reviewed concerned with the processes of scattering, sputtering, ion-electron and ion-photon emission at grazing incidence of medium-energy ions at the surface of monocrystalline, polycrystalline and amorphous targets. The singularities of these processes are revealed that can be attributed to transition to conditions of ion beam total reflection at the solid boundary, i.e. to the effect of channeling above the surface (GAS). The possibility is discussed of the experimental determination of critical angle of GAS, related to penetration of ions through the surface potential barrier. The differences of GAS from the effects accomplished under the surface, in the bulk of crystalline targets, termed as surface channeling are pointed out