Metals, properties electron emission

Mass spectrometry, which is the only technique that can be used to characterize met-cars and related metal-carbide clusters, implies that the detected clusters are ionized. This requirement opens a route to a variety of experimental procedures enabling insight to be gained into physical properties such as ionization energies, electron affinities, structure, and collective electronic properties such as thermionic electron emission and delayed atomic ion emission. 

Many experimental methods for studying H and H induced effects on metals are known. Most of them are used for surface and adsorption studies in general, a few of them, however, are specific to H on metals. The direct detection of H on metals by some surface sensitive methods is rather difficult because of the low atomic number of H. Auger electron emission e.g. does not work principally, photoemission has extremely low cross section and X-ray scattering is very weak even at grazing incidence. Thus, in many cases, one does not analyze H directly but the H induced variations of the substrate properties. (See also Malinowski, 1983). 

Amorphous carbon (a-C) films have a uniquely intrinsic stress ( 12 GPa) that is almost one order of magnitude higher than those found in other amorphous materials such as fl-Si, a-Ge, or metals (<1 GPa) [98]. Applying pressiue to a material, one can modify its electronic properties, e.g., band structure, resistivity, work function, due to the stress [99]. Poa et al. [98, 100] found a correlation between the stress and the threshold field for electron emission, as shown in Fig. 16.14. 

Mesons, summary of properties, 11-1 to 55 Metal oxides, secondary electron emission, 12-120... 

Uses. In spite of unique properties, there are few commercial appUcations for monolithic shapes of borides. They are used for resistance-heated boats (with boron nitride), for aluminum evaporation, and for sliding electrical contacts. There are a number of potential uses ia the control and handling of molten metals and slags where corrosion and erosion resistance are important. Titanium diboride and zirconium diboride are potential cathodes for the aluminum Hall cells (see Aluminum and aluminum alloys). Lanthanum hexaboride and cerium hexaboride are particularly useful as cathodes ia electronic devices because of their high thermal emissivities, low work functions, and resistance to poisoning. 

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