Regensburg 2010 – scientific programme

Parts | Days | Selection | Search | Downloads | Help

O: Fachverband Oberflächenphysik

O 73: Solid/liquid interfaces II (focussed session)

O 73.8: Talk

Thursday, March 25, 2010, 17:30–17:45, H33

Step bunching instability of Au(11n) vicinal surfaces in electrolyte — •Mohammad Al-Shakran¹, Guillermo Beltramo¹, Harald Ibach², and Margret Giesen¹ — ¹Institute of Bio-and Nanosystems ,IBN4, Jülich Forschungszentrum GmbH — ²Institute of Bio-and Nanosystems ,IBN3, Jülich Forschungszentrum GmbH

Flame annealed vicinal Au(11n) electrodes, n=5, 7, 9 11, 17, were studied by means of electrochemical scanning tunneling microscopy (STM), cyclic voltametry (CV) and capacitance curves in sulfuric and perchloric acid solution. STM results show that Au(11n) is unstable against step bunching. The surfaces arrange into alternating stripes of reconstructed surface (almost free of steps) and steep, unreconstructed step bunches. Though very stable, the step bunches still show a high mobility of individual steps within the bunch, indicating that the step bunches formed after flame annealing represent an equilibrium structure even at higher electrode potentials. Analyzing the step-step distance distribution shows that the relative amount of reconstructed area shifts with potential. As a consequence, the CVs of Au(11n) show a distinct change in the peak structure as well as in the minimum of the capacitance curves representing the potential of zero charge (pzc) which surprisingly is still well defined. We could show that a well-defined minimum in the capacitance curves exists below a maximum structure size of reconstructed and unreconstructed areas. Our results offers for the first time a comprehensive interpretation of the complex structure of CVs and capacitance curves on vicinal Au(11n) surfaces.