Scientists visualize and differentiate types of atomic bonds
Scientists have been able to measure and visualize individual atoms for some time now. Then, upping the ante, they’ve increased the resolution and have measured individual covalent bonds. But Leo Gross and a team of scientists at IBM Research in Zurich were not content with simply seeing bonds, so they used atomic force microscopy to actually discriminate between types of covalent bonds.
Atomic force microscopy uses a very small probe to "feel" the repulsive force of electrons at a surface or in a molecule. To get the sub-atomic resolution they needed, the IBMers attached a single carbon monoxide molecule on their probe to make the tip atomically sharp. They probed molecules, made of mostly of carbon, in order to compare the different bonds. One of the molecules examined is essentially a small network of carbon rings in a honeycomb pattern (hexabenzocoronene for you chemistry wizards). They found that the bonds in the center carbon ring have a larger electron density than the neighboring bonds, as evidenced by a larger repulsive force on the atomic probe. This increased electron density appears as brighter bonds in the image above . With this type of molecular imaging, these researchers say they can measure differences in bond lengths as small as 3 picometers which can serve to enhance the study of atomic-scale phenomena.
Via: New Scientist