Characterization of the chemical architecture of carbon-fiber microelectrodes. 2. Correlation of carboxylate distribution with electron-transfer properties.

Correlation of the chemical architecture of the surface of 10-microns-diameter carbon-fiber microelectrodes (illustrated by the fluorescence intensity of FITC-labeled carboxylates) and the rate of electron transfer of the surface (illustrated by the intensity of the electrogenerated chemiluminescence of luminol) allows the development of quantitative relationships between the chemical structure of an electrode surface and its electron-transfer properties. A fluorescence microscope equipped with a Peltier-cooled charge-coupled device was used to image these electrode surfaces with submicron spatial resolution. The total fluorescence emission observed at electrochemically treated electrodes was higher than that of controls while the voltammetric behavior and integrated ECL intensity of luminol were very similar. Imaging spectroscopy with submicron spatial resolution was able to demonstrate the microscopic heterogeneity of these surfaces and to assess the effect of the production of carboxylates on the rate of electron transfer of luminol.