A technique for identifying individual atoms on surfaces. In the atom-probe field-ionization microscope (FIM) there is a hole in the fluorescent screen, with which the FIM image of an adsorbed atom is brought into coincidence. The gas causing the imaging is removed. The adsorbed atom is removed as an ion by a pulse of potential difference. The atom then passes in the same direction as the gas ions, through the hole in the screen. This enables the atom to be identified by a mass spectrometer behind the screen. Atom-probe FIM identifies both the type and the position of the atom and can be used to observe atomic processes, such as evaporation, with the pulse used for analysis lasting about 2 nanoseconds.