Surface vibrations in alkanethiol self-assembled monolayers of varying chain length

The effects of chain length on the surface vibrations of alkanethiol monolayers on Au(III) was investigated. The alkanethiols on Au(III) exhibit a distinct single phonon inelastic scattering event with a largely invariant energy. The molecular dynamics simulation suggest that the frequencies of the lower energy vibrations are relatively constant with respect to the chain length. The results show that the forces between the absorbate and the substrate can be described using simple van der Waals forces between the hydrocarbon chains and the Au substrate with the sulfur chemisorbed in the threefold hollow site.