A New Microscope Reveals the Shape of Atoms

While Chemistry textbooks typically include illustrations of atoms, they are careful to warn that these images represent the probability of finding and electron at a certain palace around the nucleus. These diagrams of fuzzy spheres, barbells and clovers do not represent and actual "shape." However, researchers have imaged the electron orbitals and have shown for the first time that atoms really do look like those common text book images. Igor Mikhailovskij at the Kharkov Institute of Physics and and Technology in the Ukraine have imaged the orbitals in carbon atoms by improving field-emission microscopy. They created a chain of carbon atoms which were then dangled from a graphite tip. This chain was placed in front of a detection screen. An electric field of thousands of volts was applied between the graphite and the screen. Electrons then flowed one at a time through the graphite and along the carbon chain until the electric field pulled them off the last carbon atom. Depending on where the electrons landed on the screen, the researchers could trace the points where they left their orbital on the last atom. Denser parts of the probability clouds had a higher chance of emitting an electron, and the combined information made an image of the clouds. By changing the strength of the current, the researchers could switch the energy of the last atom's outermost electron to a higher level. These changes corresponded with the shape of the orbital as predicted. While it is possible to image single atoms using transmission electron microscopes, field-emission microscopy is much more accurate. Not only does this new technique confirm textbook diagrams, it also may lead to new discoveries about the properties of chains of carbon atoms. Looking towards the future, these chains may be useful in atomic-scale computers.

Posted by Justine Hoch