Richardson’s constant

Here, (p is the work function of the filament material, and A is Richardson s constant, given by A = AnmJ elh, where /Wg is the electron mass and h = 6.62 10 Js is Planck s constant. The field-induced term is A

vacuum permittivity. Because of the exponential variation above, materials such as tungsten that can survive operation at very high temperatures are required. Difficulties in fabrication and thermal management have hindered the development of integrated hot filament sources. 

The phenomenon of compensation is not unique to heterogeneous catalysis it is also seen in homogeneous catalysts, in organic reactions where the solvent is varied and in numerous physical processes such as solid-state diffusion, semiconduction (where it is known as the Meyer-Neldel Rule), and thermionic emission (governed by Richardson s equation ). Indeed it appears that kinetic parameters of any activated process, physical or chemical, are quite liable to exhibit compensation it even applies to the mortality rates of bacteria, as these also obey the Arrhenius equation. It connects with parallel effects in thermodynamics, where entropy and enthalpy terms describing the temperature dependence of equilibrium constants also show compensation. This brings us the area of linear free-energy relationships (LFER), discussion of which is fully covered in the literature, but which need not detain us now. 

Many modifications of the basic Ostwald geometry are employed in different situations. One example is the Cannon-Fenske routine viscometer (Fig. 6.37b) which is used in the oil industry for measuring kinematic viscosities of 0.02 m2/s and less(4<). As viscosity is sensitive to variations in temperature, these types of viscometer are always immersed in a constant temperature bath. They are not normally suitable for non-Newtonian fluids although FAROOQI and Richardson(47) have employed a capillary viscometer to characterise a power-law fluid. 

Constantin Tambo s model [kgdm ] constants in the model of Richardson and Zaki [... 

Action ak-shon n. Action is measured by the product of work by time. Cgs units of action are the erg-second and the joule-second. Dimensions (ML T ). Plank s quantum or constant of action is 6.62006876x 10 J.s. Giambattista A, Richardson R, Richardson RC, Richardson B (2003) College physics. McGrawHill Sci-ence/Engineering/Math, New York. 

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