Photoelectric cathode, secondary electron emitting cathode, electron multiplier tubes, and photomultiplier tubes

摘要

A cathode for photoelectric emission or a cathode for secondary electron emission comprises a thin film made of a material which emits photoelectrons (4) by an incident light (3) or emits secondary electrons by an electron input on a base substrate and of which an average particle size is 200 nm to 2000 nm. It is preferred that the average particle size is nearly equal to an average diffusion length of the particle of excited electron. Further, the average particle size is preferably larger than the mean value of penetration lengths of inputted electrons or incident lights in the particles. Moreover, preferably convexities and/or concavities formed of particles each having the average particle size are formed on all over the surface of a plane of input for the light or electron. Further, it is preferred that the thin film is activated by an alkali metal and is made of compounds of at least one kind of an alkali metals and an antimony metal. Moreover, it is preferred that a layer having high reflectance against lights is inserted between the base substrate and the thin film. Thus, according to the cathode for photoelectric emission or the cathode for secondary electron emission, photoelectrons or secondary electrons are generated effectively and emitted from the cathode for photoelectric emission or the cathode for secondary electron emission. IMAGE