  Direct imaging of single molecules at nanostructured interfaces is a grand
challenge, with potential to enable new, precise material architectures and
technologies. Of particular interest are the structural morphology and
spectroscopic signatures of the adsorbed molecule, where modern probes are only
now being developed with the necessary spatial and energetic resolution to
provide detailed information at molecule-surface interface. Here, we directly
visualize the binding of individual m-terphenyl isocyanide ligands to a
reconstructed Au(111) surface through scanning tunneling microscopy (STM) and
inelastic electron tunneling spectroscopy (IETS). The site-dependent steric
pressure of the various surface features alters the vibrational fingerprints of
the m-terphenyl isocyanides, which is characterized with single-molecule
precision through joint experimental and theoretical approaches. This study for
the first time provides molecular-level insights into the
steric-pressure-enabled surface binding selectivity, as well as its effect on
the chemical properties of individual surface-binding ligands.
