Electrochemical surface plasmon resonance: Basic formalism and experimental validation

A quantitative formalism of electrochemical surface Plasmon resonance (EC-SPR) was developed for studying electrochemical reactions. The EC-SPR signal from the reactions was found to be a convolution function of electrochemical current, and therefore, EC-SPR is a powerful tool that can provide information similar to the conventional current-based electrochemical techniques. As an example, potential-sweep EC-SPR was analyzed in details and was found to provide a new way to measure convolution voltammetry without the need of numerical integration. In addition to the benefits provided by the conventional convolution voltammetry, the EC-SPR has several unique advantages, including (1) spatial resolution that is particularly attractive for studying heterogeneous reactions, (2) optical properties of the reactions species that may assist identification of reaction mechanisms, and (3) high surface sensitivity for studying surface binding of the reaction species. Experiments and numerical simulations were carried out for a model system, hexaammineruthenium(III) chloride. The simultaneously measured electrochemical current and SPR response confirmed the relationship between the two quantities, and the numerical simulations were in excellent agreement with the measurements.