Paper SS2-WeM1
Adsorption of Xenon on Vicinal Copper Surfaces

Wednesday, November 11, 2009, 8:00 am, Room N

The adsorption of xenon was studied on Cu(111), Cu(221), Cu(643), and Cu(653) using temperature programmed desorption (TPD) of xenon and ultraviolet photoemission of adsorbed xenon (PAX). These experiments were performed to study the atomic and electronic structure of step-kinked, chiral copper surfaces. Xenon TPD and PAX were performed in an attempt to distinguish terrace, step-edge, and kink adsorption sites by adsorption energy (TPD) and local work function differences (PAX). The different adsorption sites could not be clearly differentiated using xenon TPD due to the complex behavior of xenon on these surfaces. Comparison of TPD spectra of R-3-methylcyclohexanone (R-3-MCHO) previously performed¹ on stepped and kinked copper surfaces suggests clear differences between Cu(643) and Cu(653) that are not apparent using xenon TPD. However, unique features of xenon adsorption on different copper surfaces were visually and numerically distinguishable using the PAX method. The PAX experiments on the copper surfaces demonstrate local work function differences between kink and step surface sites as well as step and terrace sites. A data fitting model was developed to analyze the PAX data for all four copper surfaces simultaneously. Kink sites were found to have a lower local work function than step sites, and steps, in turn, had a lower local work function than terrace sites. Step/kink adsorption of xenon is favored (for all surfaces studied at 50-70 K) at low coverages of xenon, but these sites do not saturate until monolayer coverage is reached. The results of this research provide several observations regarding the adsorptive behavior of xenon on vicinal copper surfaces.

¹Horvath, J. D.; Koritnik, A.; Kamakoti, P.; Sholl, D. S.; Gellman, A. J., Enantioselective separation on a naturally chiral surface. Journal of the American Chemical Society 2004, 126, (45), 14988-14994.