| AVS 54th International Symposium | |
| Surface Science | Tuesday Sessions |
| Session SS1-TuM |
| Session: | Catalytic Chemistry of Hydrocarbons |
| Presenter: | A.J. Gellman, Carnegie Mellon University |
| Authors: | A.J. Gellman, Carnegie Mellon University Y. Huang, Carnegie Mellon University L. Baker, Carnegie Mellon University |
| Correspondent: | Click to Email |
The high Miller index surfaces of single crystal metals have chiral structures and have been shown to interact enantiospecifically with chiral adsorbates. There are many demonstrations of this phenomenon originating from several laboratories around the world. One specific example is the adsorption of R-3-methylcyclohexanone on Cu(hkl)R&S surfaces. Several years ago we demonstrated that the adsorption of R-3-methylcyclohexanone on the Cu(643)R&S surfaces was enantiospecific. The desorption energies of R-3-methylcyclohexanone adsorbed at R and S kinks differed and the orientation of the molecule at the R and S kinks differed. Over the past two years we have completed a study of the adsorption of R-3-methylcyclohexanone on a set of 16 single crystal surfaces spanning the entire stereographic projection. In spite of the complex variety of surface structures, we find that the adsorption sites on all surfaces can be classified as terraces, step and kink type sites and have adsorption energies for R-3-methylcyclohexanone that are quite distinct from one another. One of the important observations is that some of the nominally straight step edges such as those found on the Cu(410) surface exhibit behavior similar to that of the kinks on the Cu(643) surface. This arises because these (410) step edges are in fact quite rough and are not formed by close packed rows of atoms. Recent work has focused on the structure of chiral Cu surfaces. Molecular simulation by various other groups has demonstrated that the kinked step edges of these surfaces are roughened by annealing to high temperatures and that such step edges expose a variety of different kinks sites that are not found on the ideally terminated high Miller index surfaces. Scanning tunneling micrographs of these surfaces that have been reported by other groups bear out this description of the structure of the high Miller index surfaces. Over the past year we have developed the use of Xe TPD and Xe UV photoemission as a means of obtaining spectroscopic characterization of the kink step and terrace site densities on these surfaces.