Scanning tunnelling microscopy, low-energy electron diffraction, Auger-electron spectroscopy, and temperature-programmed desorption were used to examine a metastable ‖05 52S structure which formed after the interface reaction of H2S with a Cu(100)-(2√2 x √2)R45°-O surface. This pre-oxidized copper surface displayed an enhanced reactivity towards H2S compared to the clean and annealed Cu(100) surface. Exposing 15L of H2S onto a Cu(100)-(2√2 x √2)R45°-O surface causes all the adsorbed oxygen to desorb as H2O at 164K, while leaving approximately 0.5ML of adsorbed sulfur on the surface. When this sulfur overlayer was annealed between 525 and 600K, a metastable ‖0552S reconstruction forms that was not observed after annealing similar coverages of sulfur adsorbed on an initially clean Cu(100) surface. Heating the ‖0552S surface to temperatures above 600K converted this structure to the thermally stable Cu(100)-(√17 x √17)R14°-S (i.e., ‖1¯441S overlayer. A model for the metastable ‖0552S reconstruction was proposed.

H2S Interaction with Cu(100)-(2√2 x √2)R45°-O: Formation of a Metastable ‖0552 Sulfur Surface Reconstruction. M.L.Colaianni, P.Syhler, I.Chorkendorff: Physical Review B, 1995, 52, 2076-82