ELECTROCHEMICAL OSCILLATORY BEHAVIOR UNDER A SCANNING ELECTROCHEMICALMICROSCOPIC CONFIGURATION

Diffusion coupled oscillatory behavior of the Au\HCl system was invest igated in the presence of substrate ''feedback'' of the scanning elect rochemical microscopic (SECM) system. it is shown that the amplitude o f current oscillation can be increased significantly with a slight dec rease in the oscillation frequency when the Pt substrate is positioned close to the small Au oscillating electrode. Such a ''feedback'' effe ct of the substrate may also become the driving force to induce curren t oscillation at the potential where normally electrodissolution occur s. The use of SECM to distinguish the types of oscillation mechanism o f chosen systems is demonstrated by further fulfillment of a similar e xperiment on the surface process controlled potential oscillation syst em of Pt\HCHO. For this purpose, a special home-made galvanostat-poten tiostat was employed which is generally necessary for studies of surfa ce process controlled oscillation and may also be useful for studies o f diffusion coupled oscillation under current control. It is shown tha t such an investigation under SECM configuration may provide insight i nto the oscillatory behavior from a new point of view.