Scientists have long been able to pelt lots of electrons at atoms to "see" them, but this process did too much damage to be used on molecules. Now, scientists have found a new, less destructive way to visualize whole molecules.
The research team, working at IBM, have modified an older microscopy technique know as atomic force microscopy. The stunning image above of a pentacene molecule is the result of their modified process. It might look familiar to students of organic chemistry: you can clearly see the multiple benzene rings, and even the hydrogen atoms hanging off of the carbon intersection points.
The modification to the atomic force microscopy process is what made measuring this delicate molecule possible. Atomic force microscopy detects very small attractive forces between a detector atom and the molecule being imaged. But this comes with an obvious problem: using attractive forces to measure a molecule also yanks on parts of the molecule itself.
It's similar to using a big magnet to examine a table covered in metal ball bearings. Paying close attention to how the magnet interacts with the ball bearings will tell you where the ball bearings are, but you're also likely to get some ball bearings stuck to the magnet, messing up their arrangement. When this happens on a molecular scale, it means jostling or even ripping apart delicate molecules when imaging them.
The solution that the team came up with involves using a relatively unreactive molecule as a tip to their scanner. The scientists affixed a carbon monoxide molecule to the probe, with the mostly unreactive oxygen as the only contact point with the subject molecule.
The carbon monoxide capper also takes advantage of a quantum effect called the Pauli exclusion principle. This principle says that electrons of the same quantum state can't occupy the same space. The electrons associated with the oxygen on the carbon monoxide are in the same state as those in the pentacene, providing an additional repulsive cushion between the tip of their scanner and the molecule being measured.
For their hard work, the IBM team has these really impressive images to show. These are the highest resolution pictures yet taken of a molecule like this one. You can even see the bonds between the individual atoms. It's nice to get further proof that our organic chemistry professors weren't lying to us, that things actually look like that when you get really close to them.
Microscopes zoom in on molecules at last [via NewScientist]