Re:IBM takes first 3D image of atomic bonds
by graphene on Thursday August 27, 2009 @08:47PM
(#790486)
about the brightness at the ends - I'm pretty sure that is due to the fact that this is a pi-conjugated system; that is, the pi-bonded electrons can jump around the whole molecule. This, together with the fact that the molecule is finite in size, means that the pi electrons are confined to a rectangle of lower potential energy, and when you solve the quantum mechanics (similarly to the quantum harmonic oscillator) you'll find higher electron density at the edges of the confining potential.
It should be noted that this sort of resolution has been attainable for some time using scanning tunneling microscopy, but I'm pretty sure this is a first for atomic force microscopy. STM doesn't give you a very good image of bonds -- in fact bonds are generally the thing you _don't_ see, since STM works by pulling electrons in/out and bonds are stable places where electrons really don't want to come out of or go into. AFM, on the other hand, shows bonds very nicely.
You can sorta make out where the aromatic rings are. I'm not sure why it's so bright at the ends -- any organic chemists out there who can explain that?