We speculate that the applied negative potentials used during scanning suppress the oxidation of neighboring passivating alkylthiolates to disulfide dimers and therefore can reduce desorption of the monolayer by keeping surface-bonded passivation molecules in their reduced thiolate form. The dimerization of thiols has previously been observed in thermal desorption spectroscopy experiments with self-assembled monolayers on gold, where disulfide homodimers of alkylthiolate molecules were detected as the primary species desorbing from tested gold substrates (TDS and solution phase SAM desorption papers). Furthermore, gold has been shown to serve as a catalyst for the oxidation of thiols to disulfides in the presence of oxygen. At elevated temperatures, this dimerization process is accelerated and leads to a more rapid loss of passivating molecules. This results in the formation of unoccupied sites on the gold surface available for accessory redox processes, such as oxygen reduction, leading to excessive background currents.