The researchers studied fullerenes, which is any molecule totally composed of carbon that is in the shape of a hollow ellipsoid, sphere, or tube.
One shape they worked with was the buckyball, a spherical fullerene that is shaped similar to a soccer ball.
This discovery by IBM was accomplished with a technique called noncontact atomic force microscopy (AFM).
AFM, or what is sometimes also called scanning force microscopy (SFM), is a very high-resolution type of scanning probe microscopy. It is able to resolve images down to fractions of a nanometer, which is one billionth of the length of a meter.
The Spanish and Swiss scientists wrote the paper "Bond-Order Discrimination by Atomic Force Microscopy". It was published on September 14, 2012, in the journal Science.
The paper's abstract states, "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."
The paper adds, "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."
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