Self-assembled alkanethiol monolayers on a Zn substrate: Interface studied by XPS

After having presented the organization and self-assembly of alkanethiols on zinc substrates, we focus here on the bond between the thiol sulfur and the metal. The interfacial bond between decanethiol and bulk Zn platelet has been investigated by X-ray photoelectron spectroscopy. In the presence of traces of oxygen, the Zn is oxidized and subsequently the thiolate -Zn(II)-SR is formed whatever the adsorption time tads and ageing conditions. This is attributed to the inability of the thiol to reduce the Zn(II). Results for the Zn substrate are discussed and we put into perspective the behaviour of Zn compared to other metals in the light of its great affinity towards sulfur and its complexing, soft acid and reducing properties.