Influence of Metal Adsorption on the Specific Surface Energy

This dissertation is a description of the time-dependence of surface energy for the potentiostatic adsorption of thallium, bismuth, lead, cadmium, zinc and copper on gold with (111)-main orientation in perchlorate- and sulphateelectrolyte in the underpotential region, that means above the potential of equilibrium of the metals.
The method of Koesters-Laserinterferometry has been improved. The adsorption was characterized by cyclovoltammograms, impedance-spectra and mass-coverage too.
In all cases the specific surface energy still changes a lot when the mass-coverage already assumes its equilibrium value. This deviation from the thermodynamic Lippmann-equation is due to irreversible mechanical tensions because of changes of the surface owing to changes of the structure. Such changes of the structure will be kept even desorption will take place.
After the adsorption of zinc and copper, alloys were originated. The ESCA-profile was the base for the calculation of the interdiffusion-coefficient of zinc in gold. The originate of alloys produce mechanical tensions. These tensions are growing with the square root of time.
Effective charge coefficients have been calculated out of the comparison of charge and mass-coverage. These coefficients are the ratio of charge to mass-coverage. Big effective charge coefficients are due to a desorption of water at the same time as metal adsorption happens.

The whole text is available at "Verlag Papierflieger, 1997" with the identification-number "ISBN 3-89720-002-3".

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