| Microband arrays have been successfully applied to the study of electrogenerated chemiluminescence (ECL), the production of light from ion-annihilation reactions occurring between electrogenerated species. A theory and simulation based on conformal mapping is presented for the production of steady-state ECL at double-band microelectrodes. The time courses observed for the electrode currents and ECL emission from two experimental systems, ruthenium(tris)bipyridine and 9,10-diphenylanthracene (DPA), agree well with those predicted. Both theory and simulation also predict that all electrogenerated reactants find reaction partners and undergo ion-annihilation. Thus the ECL efficiency for a given system can be readily obtained at these electrodes.;The ECL efficiency of DPA has been examined in a variety of high ionic strength solvents and solvent mixtures and found to increase with decreases in solvent dielectric and increases in the free energy available for reaction as predicted by classical Marcus electron-transfer theory. Increases in ECL efficiency were also observed with decreasing ionic strength. In high dielectric constant acetonitrile-toluene solvent mixtures these increases were found to correlate with changes in the rate constant for dissociation of the reaction encounter complex. In the low dielectric constant solvent dimethoxyethane (DME), however, significant ion-pairing of the supporting electrolyte with the electrogenerated radical ions was found to occur resulting in increases in reaction free energy with decreasing ionic strength. For DPA, these increases resulted in an ECL efficiency approaching the theoretical maximum of 25%. The ECL efficiencies of the mixed systems DPA-naphthyl phenyl ketone and DPA-benzil as well as that of rubrene were also found to increase as a function of ionic strength in DME.;The ECL arising from electropolymerized films of poly(ruthenium tris-4-vinyl-4... |
