IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Electrochemistry and Fluid-Solid Interfaces Monday Sessions
       Session EC-MoP

Paper EC-MoP2
Cadmium Underpotential Deposition on Cu(111): A Combined In Situ and Ex Situ Study

Monday, October 29, 2001, 5:30 pm, Room 134/135

Session: Poster Session
Presenter: J. Hommrich, University of Bonn, Germany
Authors: J. Hommrich, University of Bonn, Germany
Z. Park, University of Bonn, Germany
C. Stuhlmann, University of Bonn, Germany
K. Wandelt, University of Bonn, Germany
Correspondent: Click to Email
The underpotential deposition (UPD) of Cd on the Cu(111) surface was studied through ex situ (XPS, LEIS, LEED)@footnote 1@ and in situ (CV, EC-STM) methods. Cd was deposited from an aqueous solution containing 10@super-4@M CdCl@sub 2@/10@super -2@M HCl. After deposition of a complete UPD-layer a hexagonal adlayer with a 3.8 Å lattice spacing was observed by EC-STM. This superstructure shows an additional long-range periodicity (Moiré-pattern). Two rotational domains of this Moiré-pattern can be distinguished which is in agreement with ex situ LEED measurements. XPS and LEIS measurements led to the conclusion that this rather open structure (the Cd-Cd distance in bulk Cadmium is 2.98 Å) is stabilised by an adsorbed Cl overlayer. Furthermore the initial growth of the UPD-film seen by STM is discussed: In the beginning of the UPD the growth of 2D Cd islands can be monitored by STM. The observed height of these islands and the change of the contour of the substrate steps suggest that embedding of Cd into the upper substrate terraces takes place. Polarisation experiments revealed that the current-potential desorption spectra of UPD-films depend on the polarisation time. The potential of the sample was held in the UPD regime at -370 mV vs. RHE between 1 to 90 minutes. Subsequent anodic stripping of these UPD films led to the observation of an increasing charge transfer as a function of polarisation time accompanied by a change in the form of the desorption peak. In addition a roughening of the surface was observed by STM during the anodic stripping. . @FootnoteText@ @footnote 1@ C. Stuhlmann, Z. Park, C. Bach, K. Wandelt Electrochim. Acta 44 (1998) 993.