Interaction of vapor-deposited Ti and Au with molecular wires

Abstract

We have investigated the interaction of vapor-deposited titanium and gold with a self-assembled monolayer (SAM) of 4-[4′-(phenylethynyl)-phenylethynyl]-benzenthiol, an unsubstituted oligo(phenylene-ethynylene), chemisorbed on a gold substrate, a typical SAM of interest for molecular electronics. Deposited titanium atoms are observed to react in a top-down fashion with the SAM molecules to form Ti–C bonds, destroying the monolayer structure. In contrast, deposited Au atoms undergo continuous penetration through the monolayer, even at high coverages, leaving the SAM “floating” on the Au substrate surface.