A new pseudo-(100) sulphur-induced reconstruction of Cu(111) observed by scanning tunnelling microscopy

A new S-induced adsorption phase on Cu(111) has been observed by scanning tunnelling microscopy. This phase is formed by dissociation of adsorbed methanethiolate in an electron beam, and is found to coexist with the known Cu(111)/S (√7×√7)R19° and 41−14 (`zig-zag') phases. It has a near-square geometry, which we interpret in terms of a significantly expanded pseudo-(100)c(2×2)-S model. This conclusion is notable in that no equivalent Cu(100)c(2×2)-S phase exists, and the expanded lattice constant of the new phase is argued to be significant for its stability. Associated with this reconstruction is a strong corrugation which may be due to stress-induced buckling.