Design and Characterization of an Electrically Powered Single Molecule on Gold

The
surface diffusion of individual molecules is of paramount importance
in self-assembly processes and catalytic processes. However, the fundamental
understanding of molecule diffusion peculiarities considering conformations
and adsorption sites remain poorly known at the atomic scale. Here,
we probe the 4′-(4-tolyl)-2,2′:6′,2″-terpyridine
adsorbed on the Au(111) herringbone structure combining scanning tunneling
microscopy and atomic force microscopy. Molecules are controllably
translated by electrons excitations over the reconstruction, except
at elbows acting as pinning centers. Experimental data supported by
theoretical calculations show the formation of coordination bonds
between the molecule and Au atoms of the surface. Using force spectroscopy,
we quantify local variation of the surface potential and the lateral
force required to move the molecule. We found an elevation of the
diffusion barrier at elbows of the reconstruction of ∼100 meV
compared to the rest of the surface.