Electron irradiation effect on CaF2(111) studied with He atom scattering

Abstract Elastic He atom scattering was used to investigate nonintrusively the effect of electron irradiation on a high-symmetry cleaved CaF 2 (111) surface. Diffraction was observed in the [101] and [211] directions for this surface using a He supersonic beam of 64 meV. The diffraction patterns for the cleavage plane correspond to transitional symmetry of an ideal, unreconstructed CaF 2 (111) surface with a lattice vector length of 3.86 A. Layer-by-layer modification of the CaF 2 surface by the 1–12 keV e − beam was investigated by monitoring the intensity of the specular He reflection. Formation of surface F-centers is proposed to account for an increase in the specular intensity.