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https://www.ias.ac.in/article/fulltext/jcsc/121/05/0745-0756

Electrochemical and time-resolved STM; Cu UPD; co-adsorption; two-dimensional phase transitions.

Structure transitions between copper UPD adlayers on Au(111)-($1 \times 1$) in sulfuric acid and chloride containing electrolyte were investigated by in situ scanning tunnelling microscopy. We demonstrate that co-adsorbed sulphate ions in the ($\sqrt{3} \times \sqrt{3}$)R30° UPD adlayer are replaced by chloride ions and, depending on the halide coverage, a commensurate ($2 \times 2$) or a slightly distorted ($5 \times 5$)-like Cu-Cl UPD adlayer are formed. The stability ranges of these phases are controlled both by the electrode potential and the Cl^- concentration. Phase transitions between the three UPD phases were monitored by time-resolved in situ STM. The observed structure details were attributed to mechanisms based on two-dimensional nucleation and growth processes.

Ilya V Pobelov^{1 2} Gábor Nagy^{2 3} Thomas Wandlowski^{1 2}

1. Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
2. Institute of Bio- and Nanosystems IBN 3 and Center of Nanoelectronic Systems for Informational Technology, Research Center Jülich, D-52425 Jülich, Germany
3. European Commission, Place Madou 1, 1050 Bruxelles, Belgium

Published

September 2009