Adsorbate induced kink formation in straight step edges on Cu(533) and Cu(221)

Abstract

Scanning tunneling microscopy (STM) and temperature programmed desorption (TPD) measurements have revealed that the straight step edges of Cu(5 3 3) surfaces are reconstructed by the room temperature adsorption of R-3methylcyclohexanone (R-3-MCHO). STM and low energy electron diffraction (LEED) investigations have shown that the clean Cu(5 3 3) surface is composed of arrays of narrow (1 1 1) terraces separated by straight (1 0 0) steps. During room temperature adsorption of R-3-MCHO, the (1 0 0) step edges on the Cu(5 3 3) surface reconstruct, adopting a zigzag structure that exposes kinked, high Miller index step edges. The density of step edge and kink adsorption sites on Cu surfaces can be titrated by TPD of R-3-MCHO. TPD experiments also reveal the formation of kinks on the Cu(5 3 3) surface during room temperature adsorption of R-3-MCHO. Furthermore, TPD experiments on the Cu(2 2 1) surface having straight (1 1 0) step edges indicate that these also reconstruct to expose kinked step edges during R-3MCHO adsorption at room temperature. Although the kinks on such surfaces are chiral, the R- and S-forms appear to be produced in a roughly racemic (equimolar) ratio. Thus, although the reconstruction of the initially achiral Cu surfaces in the presence of a chiral adsorbate could, in principle, lead to a surface with a net chiral structure, R-3MCHO does not seem to be an effective chiral imprinting agent. � 2004 Elsevier B.V. All rights reserved.