Yesterday, I showed you a picture of 100,000 nearby galaxies, which made me feel small, even when we just look at our (relatively) local Universe. Today, let’s go down to the other end of the spectrum.
Electron microscopes have been around for a long time, and they’ve let us see some very advanced structures at amazingly high resolutions. For example, here are some individual pollen grains:
But what if you want to go deeper? What if you wanted, say, to see an individual protein and how it’s folded? Well, we have the technology (such as at the Advanced Photon Source) to image and infer the structure of very large molecules. (See below.)
But — and I’ve gotten this from BBC news — scientists have, for the first time, directly imaged an individual, simple molecule. The molecule they went to work on is known as pentacene, which looks like five benzene rings all bonded together.
Well, if you want to see things this tiny, the earlier technologies — electron microscopes and high-energy photons — won’t give you high enough resolution without also destroying the molecule you’re trying to see. What can we do?
There’s a special type of microscope known as an Atomic Force Microscope (AFM). Basically, you make a tiny, sharp, atomic needle that you move over the top of a molecule. When you approach different atoms in a molecule, the electric forces either attract or repel the needle. As the needle moves up and down, the handle that it’s attached to feels forces and torque. So, all you have to do is measure these tiny changes in force and torque, and you can image the molecule beneath it.
Well, a team from IBM Research Zurich managed to do something brilliant to an AFM tip. They used it to pick up a carbon monoxide molecule, which is just a carbon atom and an oxygen atom bonded together. This meant that the new tip — the carbon monoxide molecule attached to the original AFM tip — was just two atoms across, the highest resolution tip ever invented. They then ran this over the top of the pentacene molecule. Take a look at what they saw:
Wow. You can even see that the electrons like to live on the outside edges of the carbon rings, and that there are fourteen tiny hydrogen atoms bonded to the carbon atoms at various points. What an amazing picture; the entire molecule is only 1.4 nanometers across! Thanks to Greg Laden for this find. I’ve got nothing more about molecules, but if you want to see Conan O’Brien’s “Moleculo” skit from 2001, I’ve found that for you. And have a great weekend!