I was just reading an article in SCIENTIFIC AMERICAN from back in the 80’s about making a little stylus with the end of it an individual atom of various things like tungsten and diamond, and this thing could be put onto a surface and its electron cloud touching the electron cloud of a atom on the surface. Somehow this device, cleverly guided by new technology, could see individual atoms because although light wavelength is too big to do this, this thing could do it because the pinhole could be made small enough. That is, they used a little tiny pinhole. Ok so the question is why do they still say that you can’t see atoms when they had actual pictures of them a long time ago? They were just like the little round spheres that you think of them as and that scientists are always denying and saying well they really don’t look like that?
The technology you’re talking about is the Scanning Tunnelling Microscope (STM), which not only lets you see individual atoms but manipulate them as well. See IBM Nanotechnology for details.
(Incidentally, IBM invented the STM and has lots of other resources on the subject – try a search on “STM” or “Scanning Tunnelling Microscope” at the IBM Home Page.)
don, the probe detected the outline of the atoms and converted that to an image on a computer, but still it’s a valid question of what an atom “looks” like. I think that’s where the discrepancy lies.
Also, sometime before IBM’s STM results, I saw a picture in a technical journal (of a gallium arsenide - aluminum gallium arsenide heterojunction) that was taken with an SEM, which showed what looked like individual atoms in a lattice structure. A friend and I argued about whether these were actually atoms (I took the “no” side), so I e-mailed the author of the article. He confirmed that yes, these were the individual atoms being resolved with an SEM. So imaging atoms occurred before the STM, although the STM had much higher resolution of them.
It depends what you mean by “see”. If you mean to create a larger image based on the original atom then any drawing would fit the bill. If you mean that the actual atom reflected actual light I believe this is not possible due to the size of the atom and of the wavelength.
Not necessarily. The relative size of the target and the wavelength of the light is certainly the important criterion for diffractive scattering. However, if the atom is charged - i.e. it’s been ionised - then the interaction between it and the photons in the beam can be much stronger. There was even the case reported, some years ago now, where someone had pointed a visible laser at a single electron held in an electromagnetic trap and photographed the result. The picture is of a little isolated blue point. (The colour, of course, says more about the laser used than anything about the electron; they aren’t actually blue.) You could no doubt do the same thing with an ion.