1 research outputs found
Characteristic Contrast in Δ<i>f</i><sub>min</sub> Maps of Organic Molecules Using Atomic Force Microscopy
Scanning
tunneling microscopy and atomic force microscopy can provide detailed
information about the geometric and electronic structure of molecules
with submolecular spatial resolution. However, an essential capability
to realize the full potential of these techniques for chemical applications
is missing from the scanning probe toolbox: chemical recognition of
organic molecules. Here, we show that maps of the minima of frequency
shift–distance curves extracted from 3D data cubes contain
characteristic contrast. A detailed theoretical analysis based on
density functional theory and molecular mechanics shows that these
features are characteristic for the investigated species. Structurally
similar but chemically distinct molecules yield significantly different
features. We find that the van der Waals and Pauli interaction, together
with the specific adsorption geometry of a given molecule on the surface,
accounts for the observed contrast