Titration of Chiral Kink Sites on Cu(6 4 3) Using Iodine Adsorption

Density functional theory (DFT) and temperature programmed desorption (TPD) experiments have been used to probe the site preferences of adsorbed iodine atoms on Cu surfaces. DFT calculations are presented for iodine adsorption on Cu(1 1 1), Cu(1 0 0), Cu(2 2 1), Cu(5 3 3), Cu(5 3 1), and Cu(6 4 3). Additional DFT calculations are presented for I adsorption on a stepped Cu surface that mimics a thermally roughened Cu(6 4 3) surface. The molecular desorption of R-3-methylcyclohexanone from clean and iodine precovered Cu(6 4 3) has been used to experimentally examine the location of iodine on this surface. Our results show that there is a strong energetic preference for iodine to adsorb at step edges on Cu surfaces vicinal to Cu(1 1 1) and that when kinks are present in surface steps, iodine prefers to adsorb in the vicinity of these kinks over adsorbing along straight step edges. Thus, the adsorption of atomic iodine can be used to selectively titrate the kink sites on intrinsically chiral Cu surfaces vicinal to Cu(1 1 1).