Cadmium underpotential deposition on Cu(111) in situ scanning tunneling microscopy.

Atomically resolved in situ STM images are presented for an underpotentially deposited (upd) cadmium layer on a Cu(111) electrode from a 10(-4) M CdCl2/10(-2) M HCl solution. The observed moiré-like structure seen in the images is analysed by means of an algebraic model for this long-range superstructure. A structure model for the upd layer is developed which reflects all features of the observed moiré pattern. Furthermore the height modulation was simulated by a hard-sphere model for the Cd overlayer and shows remarkable agreement with the detailed tunneling current density distribution of the measured STM images. The existence of translational and rotational domains is demonstrated. The results are also compared and shown to be fully consistent with previous (ex situ) low-energy electron diffraction (LEED) observations of this system. The mechanism of Cd upd involves a dynamic site exchange between preadsorbed Cl- anions and adsorbing Cd2+ cations as previously concluded from ex situ X-ray photoelectron (XPS) and low-energy ion scattering (LEIS) measurements.

[1]  K. Wandelt,et al.  A new and sophisticated electrochemical scanning tunneling microscope design for the investigation of potentiodynamic processes , 1999 .

[2]  K. Wandelt,et al.  An ex-situ study of Cd underpotential deposition on Cu(111) , 1998 .

[3]  K. Wandelt,et al.  An in-situ and ex-situ study of chloride adsorption on Cu(111) electrodes in dilute HCl solutions , 1998 .

[4]  K. Wandelt,et al.  Chloride adsorption on Cu(111) electrodes in dilute HCl solutions , 1997 .

[5]  E. Budevski,et al.  Electrochemical Phase Formation and Growth , 1996 .

[6]  P. Oden,et al.  In-situ STM investigation of Tl and Pb underpotential deposition on chemically polished Ag(111) electrodes , 1995 .

[7]  H. Gasteiger,et al.  Underpotential Deposition of Lead on Copper(111): A Study Using a Single-Crystal Rotating Ring Disk Electrode and ex Situ Low-Energy Electron Diffraction and Scanning tunneling Microscopy , 1995 .

[8]  A. Gewirth,et al.  In situ atomic force microscopy of under- and overpotentially deposited cadmium on Cu(111) , 1995 .

[9]  Yee,et al.  Comment on "Superstructures of Pb monolayers electrochemically deposited on Ag(111)" , 1994, Physical review. B, Condensed matter.

[10]  Schmidt,et al.  Superstructures of Pb monolayers electrochemically deposited on Ag(111). , 1992, Physical review. B, Condensed matter.

[11]  D. Kolb,et al.  The effect of halides on the structure of copper underpotential-deposited onto Pt(111) : a low-energy electron diffraction and X-ray photoelectron spectroscopy study , 1992 .

[12]  Samant,et al.  Underpotentially deposited thallium on silver (111) by in situ surface x-ray scattering. , 1992, Physical review. B, Condensed matter.

[13]  K. Itaya,et al.  In situ scanning tunneling microscopy of underpotential deposition of copper on platinum(111) in sulfuric acid solutions , 1991 .

[14]  G. Beitel,et al.  Atomic structure of ordered copper adlayers on single‐crystalline gold electrodes , 1991 .

[15]  M. Toney,et al.  An in-situ grazing incidence X-ray scattering study of the initial stages of electrochemical growth of lead on silver (111) , 1989 .

[16]  D. Kolb.  Structural Investigations of Electrode Surfaces , 1988 .

[17]  V. Jović,et al.  Underpotential deposition of cadmium onto Cu(111) and Cu(110) from chloride containing solutions , 2001 .

[18]  N. Washburn,et al.  In situ atomic force microscope study of lead underpotential deposition on gold (111): structural properties of the catalytically active phase , 1993 .

[19]  D. Lide.  Handbook of Chemistry and Physics , 1992 .