| Popis: |
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-3- methylcyclohexanone (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-3- MCHO 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-3- MCHO does not seem to be an effective chiral imprinting agent. |
