The effect of sulfur–metal bonding on the structure of self-assembled monolayers

The equilibrium structure of alkanethiol monolayers self-assembled on metal substrates is determined by a delicate interplay of the intermolecular chain–chain and chemisorptive substrate–head group inter actions. To understand the role of the individual constituents of this interplay, we studied the structure of biphenyl and perfluoroalkyl terminated alkanethiol monolayers self-assembled on Au and Ag. The structural characteristics of the monolayers derived from NEXAFS, FTIRRAS and XPS measurements point to a decisive role of the directional substrate–head group interactions.