posted on 2017-10-16, 00:00authored byKatharina Scheil, Nicolás Lorente, Marie-Laure Bocquet, Pascal Christian Hess, Marcel Mayor, Richard Berndt
The structure of
molecular adlayers is of great interest for surface
functionalization. As molecular complexity increases, the subtle interplay
of the relevant interactions becomes more difficult to unravel. Here,
we present a scanning tunneling microscope (STM) and atomic force
microscope study along with free-energy calculations using density
functional theory on two closely related NDI-cyclophane molecules.
These three-dimensional double-decker molecules are designed to attach
to the substrate with one subunit while the other functional moiety
is exposed to the environment. The molecular arrangements obtained
on Ag(111) are rationalized by the inclusion of adatoms from the substrate
into the structure. The presence of adatoms is identified by a drastic
change in corrugation of the STM images that takes place at moderate
bias voltages. Our calculations using density functional theory of
the system’s free-energy yield that two adatoms favorably coadsorb
with the molecules.