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-mum-diam eter carbon-fiber microelectrodes (illustrated by the fluorescence int ensity 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 r elationships between the chemical structure of an electrode surface an d its electron-transfer properties. A fluorescence microscope equipped with a Peltier-cooled charge-coupled device was used to image these e lectrode surfaces with submicron spatial resolution. The total fluores cence emission observed at electrochemically treated electrodes was hi gher than that of controls while the voltammetric behavior and integra ted ECL intensity of luminol were very similar. Imaging spectroscopy w ith submicron spatial resolution was able to demonstrate the microscop ic heterogeneity of these surfaces and to assess the effect of the pro duction of carboxylates on the rate of electron transfer of luminol.