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IBM Images a Single Molecule
chrb writes "New Scientist is reporting that researchers at IBM Zurich have managed to image a single molecule in detail for the first time. In the images of a pentacene molecule, the bonds between the carbon atoms are visible as five linked rings."
This image isn't from an electron microscope, it uses AFM (atomic force microscopy: http://en.wikipedia.org/wiki/Atomic_force_microscope), which actually touches the molecules with its tip. In this case though, they bonded a single carbon monoxoide molecule to the AFM cantilever so that it would only interact with the oxygen atoms on the pentacene molecule. I imagine it didn't image the substrate at all because of that
It doesn't actually touch the molecules, because weak force cancels out the attraction. That's kind of a key point here because touching it was too destructive to get these images in the first place.
An AFM image will often look like it has a shadow. In that case, the tip was probably scanning from the right, and it "bounced" after being raised by the pentacene. The shadow size is related to the tip speed as much as the molecule height.
A lot of microscopy like this will be done using very carefully prepared atomically smooth surfaces. A good example would be Cu(111). I haven't' dug in, but they might also work with something akin to the "depth of field" in optical work to largely exclude the effect of the background.
I likely would have had this post up about 20 earlier, but I've just managed to pick myself off the floor after taking a look at the photo. As a chemist, I personally find the verification of theory a significant milestone in our understanding. It's one thing to have a theory, and then through somewhat serendipitous means, verify the theory, but to have an actual photo, brings it to a new level.
Greg
Yes, I do have a life outside the lab, but maybe not as much of one as I once thought.