UV VISIBLE REFLECTION ABSORPTION-SPECTROSCOPY IN THE PRESENCE OF CONVECTIVE FLOW

A spectroelectrochemical technique is herein described in which the surface of a rotating disk electrode is used as a mirror to reflect a focused beam of light in the UV-vis range at a near normal incidence angle. This approach makes it possible to probe quantitatively the presence of absorbing species in the diffusion boundary layer under well-defined hydrodynamic conditions. Good agreement between theory and experiments was obtained using the oxidation of Fe(CN)64-as a model system. In particular, the absorbance difference at the diffusion limiting current was found to be proportional to the reactant concentration, c(R), for a fixed rotation rate, omega, and proportional to omega-1/2 for a fixed c(R).