Spectroscopic studies of electrochemical reactions of adsorbed dye layers

Dye reactions at transparent electrodes were studied by spectroscopic investigations using the attenuated total reflection technique. All experiments were performed by modulating the concentration and consequently the absorption itself (potential modulation). The applicability of this method has been demonstrated by studying the distribution of monomers and dimers in adsorbed dye layers (viologene) or in the vicinity of the electrode. Measurements at higher modulation frequencies have shown that unstable semiquinones in adsorbed dye layers (methylene blue, thionine) involved in the oxidation-reduction cycle could be detected.