The aim of this work is to show that the thermal stability of alkanethiol monolayers on gold can be studied out of UHV conditions in a N2 atmosphere and that the sulfur-containing thermal desorption products can be monitored with high sensitivity by means of electrochemical reductive desorption experiments. We show that the thermal behavior of the monolayer in this inert atmosphere is in very good agreement with that observed under UHV conditions. To the best of our knowledge, this is the first work that determines desorption temperatures and activation energies by electrochemical methods.
The self assembled monolayer was formed on Au(111) by the immersion method and it was then transferred to a N2 atmosphere where it was heated at different temperatures. After a given heating time, the sample was transferred to the electrochemical cell and it was examined at 298 K by means of AC impedance spectroscopy and reductive desorption experiments. The latter technique allowed to accurately monitor the sulfur content of the surface either as alkanethiolate or as atomic sulfur. The desorption temperature and the activation energy barrier for desorption could be obtained with this methodology without the need for ultra high vacuum conditions.
As a prototype alkanethiol, we used 1-hexadecanethiol (C16T). The C16T monolayer was stable and defect free up to