8 Words That Are Older Than You Think
|field emission |
The emission of electrons from the surface of a conductor, caused by a strong electric field. Field emission is used to create electron beams in certain electron microscopes, as well as in flat-panel computer and television displays, in which the electron beams produce light by striking a phosphor-coated screen.
discharge of electrons from the surface of a material subjected to a strong electric field. In the absence of a strong electric field, an electron must acquire a certain minimum energy, called the work function, to escape through the surface of a given material, which acts as a barrier to electron passage. If the material is placed in an electric circuit that renders it strongly negative with respect to a nearby positive electrode (i.e., when it is subjected to a strong electric field), the work function is so lowered that some electrons will have sufficient energy to leak through the surface barrier. The resulting current of electrons through the surface of a material under the influence of a strong electric field is called field emission. This effect is utilized in the field-emission electron microscope, which in some instances achieves resolution of atomic dimensions. Field emission is sometimes called high-field emission to distinguish it from the Schottky effect (q.v.), which influences electron emission at lower values of the applied field