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 interactions. 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.