Dushman

The analytic theory outlined above provides valuable insight into the factors that determine the efficiency of OI.EDs. However, there is no completely analytical solution that includes diffusive transport of carriers, field-dependent mobilities, and specific injection mechanisms. Therefore, numerical simulations have been undertaken in order to provide quantitative solutions to the general case of the bipolar current problem for typical parameters of OLED materials [144—1481. Emphasis was given to the influence of charge injection and transport on OLED performance. 1. Campbell et at. [I47 found that, for Richardson-Dushman thermionic emission from a barrier height lower than 0.4 eV, the contact is able to supply... 

The pressure of gas in the source chamber was determined from the pressure in the gas reservoir (measured with a McLeod gage) by using Dushman s (11) relations for viscous and molecular flow in the higher and lower ranges of pressure, respectively. 

From Fig. 6.14 it becomes clear why one must heat filaments to very high temperatures to see electron emission in electron guns. Only the part of the electron distribution that has obtained energies above 0 can be utilized. The occupation number at the vacuum level can be approximated by e hT leading to the well known Richardson-Dushman formula, which describes the fluxj of electrons evaporating from a surface with work function 0 at temperature T ... 

Redox Reaction lodide/lodate - Dushman Reaction... 

The Dushman reaction was chosen for its changes in UV-visible properties to demonstrate the capability of such in-line monitoring in a micro reactor [22],... 

Dushman Reaction Investigated in Micro Reactors Organic synthesis 91 [OS 91] Redox reaction of iodate and iodide... 

Figure 4.98 With decreasing of residence time a lower Dushman reaction product is observable, indicated by in-line spectrometry [22].

The arsenous acid-iodate reaction is a combination of the Dushman and Roebuck reactions [145]. These reactions compete for iodine and iodide as intermediate products. A complete mathematical description has to include 14 species in the electrolyte, seven partial differential equations, six algebraic equations for acid-base equilibriums and one linear equation for the local electroneutrality. 

S Dushman, JM Lafferty. Scientific Foundations of Vacuum Technique. 2nd ed. New York Wiley, 1962. 

Evaporation from an alloy source largely avoids the problems of source geometry which may be encountered in simultaneous evaporation from separate pure metal sources. The success of the method depends on the relative vapor pressures of the component metals in the alloy source because one component metal with a substantially higher vapor pressure will evaporate preferentially. The alloy film will then be rich in the more volatile component compared with the composition of the source and may also be stratified into layers of different composition. Evaporation from alloy sources is discussed in detail by Dushman (43) and Holland (44) on the basis of Raoult s law, and it is possible to predict which metal pairs... 

S. Dushman Scientific foundations of vacuum techniques, Wiley, New York (1962)... 

Dushman (Jour. Phys. Ghem. xiv. 885,1910) found 8 = -040 mm. under similar conditions, whilst Brunner (loo. cit), found that was approximately constant. 

Figures 4 to 7 are the direct result of experiments. These results can be generalized by deducing the work functions for the three evaporation processes. For electron emission the relation between current density and <( e is given by the well-established Richard-Dushman equation...

In this section we shall discuss the relationship between the work described in this chapter and that which preceded it. The chief objective will be to compare the techniques, the experimental results, the interpretation of these results, and the theoretical concepts. We shall attempt to point out which results have stood the test of time and which results need to be discarded or modified. This discussion will be limited to the work of the following people and their associates Langmuir, Frankenburg, Roberts and Rideal, and Beeck. In making this selection, we unfortunately exclude many important contributions and for this we apologize in advance. To compensate partially we refer the reader to the excellent and comprehensive books by Adam (20) and Dushman (21). 

Dushman put forward the equation k = ve hvlkT for the velocity constant of a unimolecular reaction. The values of E, which in this equation are equal to Nhv, vary by a factor of less than 3 from reaction to reaction. Thus it is not easy to differentiate in practice between Dush- J. Amer. Chem. Soc., 1921, 43, 397. 

Thermal transpiration is discussed in many books on vacuum technology. See, for example S. Dushman, Scientific Foundations oj Vacuum Technique, 2nd ed.t rev. by J. M. Laffcrty et al. (New York Wiley, 1962). 

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