[feeld-ahy-uh
n, -ahy-on] 
| a device in which the atomic structure of the surface of a conductor is made visible by introducing helium gas into the device and applying a high voltage to ionize and accelerate the gas toward a fluorescent screen. |
| field ion microscope
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. |