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

A new S-induced adsorption phase on Cu(1 1 1)has been observed by scanning tunnelling microscopy. This phase is formed by dissociation of adsorbed met hanethiolate in an electron beam, and is found to coexist with the known Cu (1 1 1)/S (root7 x root7)R19 degrees and /(4)(-1) (1)(4)/ ('zig-zag') phase s. It has a near-square geometry, which we interpret in terms of a signific antly expanded pseudo-(1 0 0)c(2 x 2)-S model. This conclusion is notable i n that no equivalent Cu(1 0 0)c(2 x 2)-S phase exists, and the expanded lat tice constant of the new phase is argued to be significant for its stabilit y. Associated with this reconstruction is a strong corrugation which may be due to stress-induced buckling. (C) 2001 Elsevier Science B.V. All rights reserved.