Helium diffraction from MgO(100)

Helium diffraction from the cleavage plane of MgO was studied with different He energies and different angles of incidence. Hard-wall intensity analyses of in-plane and out-of-plane spectra obtained with 63 and 86 meV yielded the corrugation function, which is simply sinusoidal in both unit-cell directions with an amplitude of 0.18 ± 0.02Å. A discussion of the total corrugation amplitudes of MgO and NiO on the one side and of LiF and NaCl on the other, in connection with the ionic radii of the respective constituents, provides evidence that the ionic bonding is largely maintained at the surface of the alkali halides, but that an appreciable charge redistribution takes place at the surface of the oxides. © 1982.