AVS 45th International Symposium
    Surface Science Division Wednesday Sessions
       Session SS2-WeM

Paper SS2-WeM1
Monte-Carlo Simulation of the Adsorption and Desoption of CF@sub 4@ on Cu/CuO(110)

Wednesday, November 4, 1998, 8:20 am, Room 309

Session: Gas-Surface Dynamics
Presenter: M. Hohage, University of Wisconsin, Madison
Authors: M. Hohage, University of Wisconsin, Madison
V. Diercks, Forschungszentrum Jülich, Germany
P. Zeppenfeld, Universität Linz, Austria
M.G. Lagally, University of Wisconsin, Madison
Correspondent: Click to Email
The unique adsorption and desorption dynamics of CF@sub 4@ on the Cu/CuO(110) stripe phase is reproduced by a Monte-Carlo simulation to reveal the underlying processes on the molecular scale. As observed by means of thermal energy atom scattering (TEAS), at temperatures above 20K CF@sub 4@ adsorbs preferentially on the CuO stripes.@footnote 1,2@ A comparison of these adsorption measurements with a Monte-Carlo simulation is used to determine the parameters of the CF@sub 4@ diffusion on Cu and on CuO. With the knowledge of these diffusion parameters the more complicated desorption of CF@sub 4@ is analyzed. TEAS and TDS measurements show that annealing the sample with a rate of 1K/s leads to desorption between 55K and 70K@sub 2@. Two well-separated peaks occur. The peak at lower temperature is related to the desorption from the Cu stripes, whereas the peak at higher temperatures is related to the desorption from the CuO stripes. This desorption behavior as well as shifts of the desorption peaks in dependence of the composition of the surface (amount of O on the surface) is reproduced by a Monte-Carlo simulation including the previously determined diffusion parameters as a fixed input. The different features of the desorption spectra, i.e. peak positions, peak shifts, and peak shapes, are assigned to binding energies and diffusion barriers on the molecular scale. This allows the development of a consistent model of the CF@sub 4@ adsorption and desorption dynamics. *Supported by NSF and by the Alexander von Humboldt-Stiftung @FootnoteText@ @Footnote 1@P. Zeppenfeld, V. Diercks, Ch. Tölkes, R. David, and M. A. Krzykowski, Appl. Surf. Sci. (1998) in print. @Footnote 2@V. Diercks, Ph.D. thesis, Bonn 98