Self-assembled monolayers (
SAMs) on Au(111) are able to control the functionality of a
gold surface. We use scanning tunnelling microscopy (STM) in air and contact angle measurements to compare the morphology and the chemistry of three alkylthiol
SAMs differing by their tail groups:
1,9-nonanedithiol (NDT), 1,4-butanedithiol (
BDT) and
11-mercaptoundecanol (MUOH). STM reveals very different morphologies: a hexagonal lattice for MUOH and parallel rows for NDT and
BDT. In the case of NDT, we find that the
thiol tail groups may form
disulfide bridges with long immersion times. The availability of the -SH group for chemical reactions is demonstrated by attaching
gold nanoparticles (AuNPs). When the
thiol tail group is available, AuNPs readily attach as shown with atomic force microscopy (AFM). When
disulfide bridges are formed, the
gold surface is not able to bind nanoparticles.