Material scientists have watched crystals grow atom-by-atom for the first time—which will allow incredibly fine-grained control of how their microscopic structures are grown in the future.
The researchers took a thin film of molecules containing the metal osmium, carbon and other elements, then fired a beam of electrons at it. That caused the molecules to break down, releasing a single osmium atom while the carbon formed a supporting graphene lattice—containing impurities from the the other elements present—below.
Those impurities caused the osmium atoms to travel slowly on the surface of the sample, which meant that a scanning electron microscope could work fast enough to see them gather together and form a crystals structure, one by one, on top of the graphene. In fact, it's the first time scientists have ever observed the atom-by-atom assembly of crystals; you can see some snapshots from the process in the image above.
That may sound neat, but it's going to prove very useful, too. At the nanoscale, it's hard to predict how atoms and molecules will come together to form different shapes—say, rods, spheres or flat dots—but they all have radically different properties. Now, this research should help scientists learn how it may be possible to control the way they come together, consistently producing the nano-sized object that they really want. That's no small achievement. [Nature Communications via New Scientist]