Scanning tunneling microscopy study of S adsorption on Ni(111)

Abstract

The chemisorption of sulfur on Ni(111) has been studied by scanning tunneling microscopy. At initial adsorption individual S atoms appear as protrusions 0.3–0.4 Å high, forming a local p(2×2) structure near step edges. The p(2×2) structure is found to be a simple S overlayer structure. After further H₂S exposure the surface undergoes a reconstruction to a (5√3×2) structure, accompanied by a homogeneous nucleation of small islands resulting from an ejection of Ni atoms from terraces. The Ni density of 0.80±0.03 ML in the (5√3×2) structure has been determined by measuring the amount of Ni atoms used to build the islands.