Thermoelectron emission

For the metal/metal boundary, these potential differences (Aj i/ ) can be defined by the difference of work functions [22]. The latter can be obtained from the photoelectron emission (or thermoelectron emission) and also directly by using a circuit... 

When heated, some surfaces emit copious amounts of electrons (thermoelectron emission). Tungsten and thoriated tungsten are common examples but lanthanum hexaboride (LaB ) is an interesting material in that, at a temperature of 1700 C, it has an electron emission of >20 A/cm, which is much higher than that of tungsten at the same temperature. Hot surfaces of these materials are used as electron sources in some ion and plasma sources. 

The secondary electron emission by ion bombardment is low, whereas high rates from thermoelectron emission would be expected if high temperatures were present. 

Hard arc High current, sustained arc usually caused by shorting (by a flake) or thermoelectron emission from a heated oxide particle on a high voltage electrode. 

Hollow cathode (plasma) A cathode with a deep cylindrical cavity or tube such that the electrons are trapped in the cavity and are effective in ionizing gases in it. The cathode can be heated to the point that there is thermoelectron emission (hot hollow cathode). The hollow cathode can be used as an electron source. 

Thermionic emission Electron emission from a heated surface. This term is a misnomer since generally few ions are emitted from a heated surface for most materials. Exceptions are fluorine, cesium, potassium, and rubidium, which can be ionized by evaporation from a heated surface. See also Thermoelectronic emission. 

Thermoelectronic emission Electron emission from a heated surface. Sometimes called thermionic emission, which is poor terminology. 

Adsorption capacities were studied -by Atomic Emission Spectroscopy (Vista-Pro ICP-OES from VARIAN) for lead analysis and -by UV Spectrometry (Nicolet Evolution 300 from ThermoElectron Corporation) for p-nitrophenol determination. 

Cold cathode A non-thermoelectron-emitting cathode that emits electrons, usually by secondary electron emission, under ion bombardment or by radioactive decay. See also Field emission. 

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