title: Coupling Electrochemistry with Fluorescence Confocal Microscopy To Investigate Electrochemical Reactivity: A Case Study with the Resazurin-Resorufin Fluorogenic Couple.
abstract: The redox couple resazurin-resorufin exhibits electrofluorochromic properties which are investigated herein by absorption and fluorescence spectroelectrochemistry and by electrochemically coupled-fluorescence confocal laser scanning microscopy (EC-CLSM). At pH 10, the highly fluorescent resorufin dye is generated at the electrode surface by the electrochemical reduction of the poorly fluorescent resazurin. Performing EC-CLSM at electrode surfaces allows to monitor spatially resolved electrochemical processes in situ and in real time. Using a small (315 μm diameter) cylindrical electrode, a steady-state diffusion layer builds up under potentiostatic conditions at -0.45 V vs Ag|AgCl. Mapping the fluorescence intensity in 3D by CLSM enables us to reconstruct the relative concentration profile of resorufin around the electrode. The comparison of the experimental diffusion-profile with theoretical predictions demonstrates that spontaneous convection has a direct influence on the actual thickness of the diffusion layer, which is smaller than the value predicted for a purely diffusional transport. This study shows that combining fluorescence CLSM with electrochemistry is a powerful tool to study electrochemical reactivity at a spatially resolved level.
authors.affiliation: Chimie Analytique et Chimie des Interfaces, Faculté des Sciences, Université libre de Bruxelles (ULB) , Boulevard du Triomphe, 2, CP 255, B-1050 Bruxelles, Belgium.
authors.forename: Thomas
authors.initials: T
authors.lastname: Doneux
authors.affiliation: Univ. Bordeaux , ISM, UMR 5255, F-33400 Talence, France.|CNRS, ISM, UMR 5255, F-33400 Talence, France.
authors.forename: Laurent
authors.initials: L
authors.lastname: Bouffier
authors.affiliation: Univ. Bordeaux , ISM, UMR 5255, F-33400 Talence, France.|CNRS, ISM, UMR 5255, F-33400 Talence, France.
authors.forename: Bertrand
authors.initials: B
authors.lastname: Goudeau
authors.affiliation: Univ. Bordeaux , ISM, UMR 5255, F-33400 Talence, France.|CNRS, ISM, UMR 5255, F-33400 Talence, France.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Arbault