EXPERIMENTAL-EVIDENCE FOR ANTICORRUGATING EFFECTS IN HE-METAL INTERACTIONS AT SURFACES

We show that systematic differences occur in the corrugations of the systems Ni(110)c(2 x 4)H, and Rh(110)(1 X 3)H and (1 X 2)H, when determined from He and Ne diffraction: Whereas the hills along the H-free close-packed metal rows correspond to underlying metal atoms in all corrugations deduced from Ne diffraction, they are shifted to short bridge sites in all He-derived corrugations. This assignment is possible, as the H adatoms mark threefold hollow sites on both (110) substrates. These observations provide strong experimental support for anticorrugating effects in He-metal surface interactions as proposed by Annett and Haydock [Phys. Rev. Lett. 53, 838 (1984)].