Construction of a Scanning Tunneling Microscope for Electrochemical Studies

We have constructed a scanning tunneling microscope (STM) for electrochemical studies. Using the STM, we investigated an electrochemically treated surface of a polycrystalline silver electrode in a 0.1 M KCl solution. The STM images of the Ag electrode in the solution exhibited large asymmetric peaks resulting from the large asymmetric current spikes. We found that a plot of the current vs t -1/2, where t is time, for a single current spike satisfies a linear relation, i.e., the Cottrell equation. Thus, a diffusion-controlled electrochemical reaction was observed at a specific region by the STM.