This thesis describes work carried out to observe the dynamics of diffusion layer
growth near electrode surfaces. For the first time, these processes are observed within
1 µm of an electrode. This is accomplished by positioning an ultramicroelectrode near an electrode surface with a scanning tunneling microscope. A bipotentiostat is integrated with the scanning tunneling microscope to allow potential control of the sample cell, permitting independent control of both the electrode substrate and the ultramicroelectrode tip potentials.
The response of the diffusion layer to potentiostatic and galvanostatic stimulus of
the substrate is described. The responses to the stimulus in the absence of coupled
chemical reactions are shown to agree well with theory. The observed effects of a coupled
chemical reaction are also reported and compared to the responses generated from a
simulation program. Good agreement of the experimental data to the simulated data is
shown, which demonstrates the ability of the instrument to study homogeneous kinetics.</p