A microscope that produces images of atoms in resolution at the atomic scale on a sharp, electrically charged, super-cooled metal tip by means of field ionization. Ions repelled from the tip form a pattern on a detector, providing an image of the sample on the tip.
A microscope that produces an image of a sample of molecules, or even individual atoms, on the surface of a metal tip. Gas atoms absorbed in the tip are positively ionized by an electric field, and the tip is given a strong positive electric charge, causing the ions to be repelled and thus fly away from the tip. The pattern that the ions form on a collecting surface provides an image of the sample on the tip.