Reversible displacement of chemisorbed n-alkanethiol molecules on Au(111) surfaces. An atomic force microscopy study

Atomic force microscopy has been used to study the structure and the stability of CH₃(CH₂)₉SH and CH₃(CH₂)₁₇SH molecules self-assembled on a Au(111) surface as a function of the load applied by the tip. Atomic resolution images taken during a loading and unloading cycle have revealed two sudden transitions corresponding to changes of the periodicity from a (√3 × √3) R30° (due to thiol layers) to a (1 × 1) (due to Au(111), and back to the (√3 × √3)R30° of thiol layers. These results represent the first observation that under high load, self-assembled n-alkanethiol molecules on Au(111) can be reversibly displaced on the substrate surface by a sharp tip during the scan.