Potential-induced structure transitions in self-assembled monolayers: II. Propanethiol on Au(1 0 0)

The structure of propanethiol self-assembled monolayers (SAMs) on Au(1 0 0) in 0.1 M H₂SO₄ has been investigated as a function of electrode potential by in situ scanning tunnelling microscopy (STM). These studies reveal a potential-induced, reversible transition between an in essence quadratic and a distorted hexagonal structure. We suggest that a thiolate-driven surface reconstruction, similar to Au(1 0 0)-(hex), is responsible for the hexagonal SAM structure, whereas the quadratic one refers to the unreconstructed substrate.