I have read many questions on this site and elsewhere about STM's but none of them specifically talk about how they actually "grab" and move the single atoms.
The best I found, is saying that the tip comes a few nm close to the atom and turns on an electric current, thus causing electrons and photon to tunnel between the tip and the surface.
However, nowhere does it specifically state how exactly they "grab" and move the single atoms.
The image above is from the MacMillan/McGraw-Hill California Science Grade 5 book.
There are two main ideas that come to mind:
Even if the tip is only a few atoms wide, it is still not obvious how "grabbing" the single atom is possible, that is, what sticks the atom to the tip, and does it so, that later the atom can still be separated and "put" somewhere else (moving it)
single atoms are not just "hanging" around, floating there, they are attached to surfaces by the EM force, which is, pretty strong. How can the tip individually "tear" off a specific atom and make sure it does not get destroyed/altered?
I have not found any reputable source that would specifically talk about the way they "grab" the single atoms and move them.
- How exactly can you "grab" a single atom with a scanning tunneling microscope?