cathodoluminescence

cathodoluminescence [¦kath·ə‚dō‚lüm·ə′nes·əns]

(electronics)

Luminescence produced when high-velocity electrons bombard a metal in vacuum, thus vaporizing small amounts of the metal in an excited state, which amounts emit radiation characteristic of the metal. Also known as electronoluminescence.

---

Cathodoluminescence

A luminescence resulting from the bombardment of a substance with an electron (cathode-ray) beam. The principal applications of cathodoluminescence are in television, computer, radar, and oscilloscope displays. In these a thin layer of luminescent powder (phosphor) is evenly deposited on the transparent glass faceplate of a cathode-ray tube. After undergoing acceleration, focusing, and deflection by various electrodes in the tube, the electron beam originating in the cathode impinges on the phosphor. The resulting emission of light is observed through the glass faceplate, that is, from the unbombarded side of the phosphor coating.

The luminescence of most phosphors comes from a few sites (activator centers) occupied by selected chemical impurities which have been incorporated into the matrix or host solid. Because of the complex mode of interaction of cathode rays with phosphors, the energy efficiency of light production by cathodoluminescence is lower than the best efficiencies obtainable with photoluminescence. Conversion efficiencies of currently used display phosphors are between 2 and 23%. See Luminescence