Bond-Order Discrimination by Atomic Force Microscopy

IBM has done it again. This is the first time in the history of science that bonds have been discover using Atomic Force Microscope.

Leo Gross,1* Fabian Mohn,1 Nikolaj Moll,1 Bruno Schuler,1 Alejandro Criado,2
Enrique Guitián,2 Diego Peña,2 André Gourdon,3 Gerhard Meyer1

We show that the different bond orders of individual carbon-carbon bonds in polycyclic aromatic
hydrocarbons and fullerenes can be distinguished by noncontact atomic force microscopy (AFM)
with a carbon monoxide (CO)–functionalized tip. We found two different contrast mechanisms,
which were corroborated by density functional theory calculations: The greater electron density in
bonds of higher bond order led to a stronger Pauli repulsion, which enhanced the brightness of
these bonds in high-resolution AFM images. The apparent bond length in the AFM images
decreased with increasing bond order because of tilting of the CO molecule at the tip apex.