I posted images of real pentacene molecules the other day, but now the single molecule/single-atom imaging field has reached another milestone. There’s a paper coming out in Physical Review B from a team in Kharkov using a field emission electron microscope. At heart, that’s a pretty old type of machine, first invented back in the 1930s, and it’s long provided images of the arrangements of atoms in metal surfaces. (More precisely, you’re getting an image of the work function, the energy needed to remove electrons from the material).
But this latest work is something else entirely. The researchers have improved the resolution and sensitivity, narrowing things down to single-atom tips. So instead of a tungsten surface, we have a single carbon atom at the end of a chain. And instead of the behavior of the electons in a bulk metal, we have the electron density around one nucleus. Behold the s and p orbitals. Generations of students have learned these as abstractions, diagrams on a page. I never thought I’d see them, and I never thought I’d see the day when when it was even possible. As always, I react to these things with interest, excitement, and a tiny bit of terror at seeing something that I assumed would always be hidden.