Atom printing

Just went to the sweetest talk about 0.2A (1A lateral) resolution atomic tomography. Basically kick atoms off a (needle) surface with an electrical pulse or laser and then accelerate them into a position sensing detector. The time-of-flight gives you the mass-to-charge ratio so you can tell element and isotope. As the electric field spreads out almost radially away from the needle you get a lot of magnification and can tell the originating position quite accurately.

Of course, this imaging method destroys the sample.. but wouldn't it be cool if you could do it in reverse to place individual atoms into an object? It would be difficult to say the least, but the result would be awesome. Not only that, but it could be a quite automatic process.

You could have different print heads for different elements. Perhaps even the same thing in reverse, a laser that kicks atoms off the "print head" and then the freed ion travels along the electric field line and hits the "needle". Of course, you would have to ensure that the ion got kicked off with a small velocity or you would have quite bad lateral resolution. This low velocity thing would probably result in the ion just reattaching to the material. So this is probably hard to do, because the whole point of using a needle is presumably so as to get strong electric fields (and thus high acceleration) when the ion is first ionised. Perhaps this is why this technique won't work.

But what if you had two needles? Boot the atoms off one, and attach them to the other. Ensure that only certain atoms land by having a (macro scale) aperture between them and detect when atoms land.