OBSERVATION OF A MISSING-ROW STRUCTURE ON AN FCC(111) SURFACE - THE (5-ROOT-3X2)S PHASE ON NI(111) STUDIED BY SCANNING-TUNNELING-MICROSCOPY

A missing-row reconstruction of an fcc (111) metal surface has been observed for the first time. Direct observation of many small islands formed at the surface during S adsorption on Ni(111) indicates that a long-range mass transport takes place and that the surface undergoes a reconstruction. We present evidence that this reconstruction corresponds to a model in which every fifth Ni [110] surface row is missing, with a total of 0.4 monolayer of S atoms adsorbed in threefold hollow positions on the surface and in the created troughs. The driving force for this novel missing-row reconstruction is proposed to be adsorption-induced surface stress.