Interaction of vapor-deposited Ti and Au with molecular wires

摘要

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.