Fine structure in the voltammetric desorption curves of alkanethiolate monolayers chemisorbed at gold

This paper presents the preliminary results from a study of the chain length dependence of the reductive desorption and oxidative re-deposition processes of alkanethiolate monolayers on Au(111) electrodes. In contrast to the more extensively studied short chain length monolayers, we report a previously undetected fine structure in the voltammetric waves for monolayers composed of alkyl chains of more than 10 carbons. The short chain systems in general exhibit a single voltammetric wave for the desorption and re-deposition processes. In contrast, multiple voltammetric waves separated by 20 to 100 mV are found for both the desorption and the re-deposition of the long chain systems. The origin of these results is examined in terms of possible differences in the adlayer domain structures and in the binding modes between sulfur and gold.