Science Questions

Can we see atoms?

Mon, 9th May 2011

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Question

Joanna, Norwich asked:

Can we see atoms? If so, how?

Answer

Chris -   Yes, you can.  In fact, it was the 30th anniversary recently of a fairly iconic image that was published by IBM.  They actually wrote the letters IBM using atoms of xenon which they manipulated around on a surface using a scanning tunnelling electron microscope.

So you can see atoms, but you’re not really seeing the atoms, what you’re seeing is the electron field created by the electrons around the atom and how they produce a current when they interact with a very fine tip on an electron microscope.

One more recent study imaged atoms in a slightly different way.  What this study did was to take a sheet of graphene, a single layer of carbon atoms, rather like a honeycomb which stack up make graphite. If you peel away single layers of graphite you get graphene.  And what this particular group in America did was to sprinkle some molecules onto this graphene sheet and then run a scanning tunnelling electron microscope across the surface.  And because the graphene is so regular in structure, it’s easy to mathematically subtract the effect of the graphene being there from any other signals that you get.  This enables them to actually see the structure and shapes of molecules.

If you wind your mind back to the days of chemistry lessons, when your teacher would draw a chain of, say, butane – four carbon atoms all linked together – and draw the kinky line of these atoms (that’s the atoms being bent and kinked, not the atoms being kinky!) how do they actually know it looks like that?  Well, if you look at these pictures they’ve published recently, they really do look like that – it’s absolutely fantastic.

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