AVS 46th International Symposium
    Surface Science Division Tuesday Sessions
       Session SS-TuP

Paper SS-TuP7
Ethene Adsorption on Cu(111), Cu@sub 3@Pt(111), CuPt@sub 3@(111), and Pt(111)

Tuesday, October 26, 1999, 5:30 pm, Room 4C

Session: Poster Session
Presenter: T. Pelster, Universität Bonn, Germany
Authors: T. Pelster, Universität Bonn, Germany
R. Linke, Eindhoven University of Technology, The Netherlands
J. Breitbach, Universität Bonn, Germany
A. Frey, Universität Bonn, Germany
M. Tanemura, Nagoya Institute of Technology, Japan
M. Grüne, Universität Bonn, Germany
R.-J. Linden, Universität Bonn, Germany
C. Becker, Universität Bonn, Germany
K. Wandelt, Universität Bonn, Germany
Correspondent: Click to Email
The adsorption of ethene on Cu(111), Cu@sub 3@Pt(111), CuPt@sub 3@(111), and Pt(111) at 100K has been investigated using high resolution energy electron loss spectroscopy (HREELS), temperature programmed desorption (TPD), ultraviolet photoelectron spectroscopy (UPS), and work function change measurements. On Pt(111) ethene forms at 100K a well known di-@sigma@-complex, whereas on Cu(111) ethene adsorbs in a weakly bonded @pi@-complex which shows typical vibration spectra very similar to gaseous ethene. On Cu@sub 3@Pt(111) and CuPt@sub 3@(111) both species can be found, with higher intensity of the @pi@-complex on the Cu@sub 3@Pt(111) and the di-@sigma@-complex on the CuPt@sub 3@(111) surface, respectively. A full peak assignment in HREELS spectra gives a strong indication for a reduction of the C-C bond order of the di-@sigma@-species going from Cu@sub 3@Pt(111) to Pt(111). This can be attributed to an electronic effect due to the dilution of Pt by Cu. Both TPD and UPS support these results. Surprisingly, ethene does not dehydrogenate on the alloys when the surface is heated in contrast to ethene on Pt(111). This can be explained by the lack of appropriate sites on Cu@sub 3@Pt(111). On CuPt@sub 3@(111) the issue is more complex since on this surface such sites are available. On this surface the process might therefore be kinetically hindered.