INFLUENCE OF THE TIP ON ELECTRODE PROCESSES AND ON MORPHOLOGIES STUDIED BY IN-SITU STM - CU AU/

A smooth surface that may be amorphous was formed on a working electro de of polycrystalline gold by sweeping the potential. In an electrolyt e of 0.01 M copper sulphate and 0.01 M sulphuric acid the morphology o f the gold surface and of copper deposits were followed by in situ STM . Gold surfaces which had previously been subjected to many cycles of potentiostatic bulk copper electrodeposition exhibited a characteristi c granular structure. On top of the granular structure the smooth gold surface was built up by surface diffusion, except underneath the tip, which shows that in situ STM only probes the surface locally. The act ion of the tip creates a cavity in the surface. From simultaneous reco rdings of current-voltage diagrams and of in situ STM images it is sug gested that both surfaces' structural transformations and gas evolutio n contribute to the total charge passed. The potential of the electrod e process depends linearly on the tip potential and it was found that the electrode process observed by in situ STM can be related to featur es of the current-voltage diagrams and of cyclic voltammograms only wh en the tip potential is zero.