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Adsorption / Chemical Kinetics / Interfaces / Seu Assembled Monolayers / Surfaces
Abstract:
STM images of self assembled alkanethiol films on gold surfaces show holes which have been identified as vacancies in the topmost gold layer. We show that this vacancy formation is accompanied by a corrosion process of gold in ethanolic thiol solutions. The amount of dissolved gold from polycrystalline substrates as a function of immersion time, thiol concentration, chain length and solvent has been investigated by Atomic Absorption Spectroscopy (AAS). The results suggest that the thiol molecule itself is the active oxidant. In case of a 1 mmol solution of docosanethiol in ethanol a gold concentration corresponding to 6% of a gold monolayer has been detected after an immersion time of 24 h. By using hexane as a solvent the amount of dissolved gold is reduced to less than 0.2%, indicating a strong solvent (e.g. polarity) dependence for the corrosion process. The kinetics of the corrosion process have been measured and compared to kinetic data related to the formation of an ordered thiol film.
