Nitrogen diffusion coefficient

Reasonable prediction can be made of the permeabiUties of low molecular weight gases such as oxygen, nitrogen, and carbon dioxide in many polymers. The diffusion coefficients are not compHcated by the shape of the permeant, and the solubiUty coefficients of each of these molecules do not vary much from polymer to polymer. Hence, all that is required is some correlation of the permeant size and the size of holes in the polymer matrix. Reasonable predictions of the permeabiUties of larger molecules such as flavors, aromas, and solvents are not easily made. The diffusion coefficients are complicated by the shape of the permeant, and the solubiUty coefficients for a specific permeant can vary widely from polymer to polymer. 

Fig. 16. The diffusion coefficient D12 for hydrogen-f nitrogen. 4, measurement of Boardman and Wild V, Waldmann O, Schafer, Corte, and Moesta , Schafer and Moesta. The line is calculated from the same parameters as the line in Fig. 15.

The experimental results imply that the main reaction (eq. 1) is an equilibrium reaction and first order in nitrogen monoxide and iron chelate. The equilibrium constants at various temperatures were determined by modeling the experimental NO absorption profile using the penetration theory for mass transfer. Parameter estimation using well established numerical methods (Newton-Raphson) allowed detrxmination of the equilibrium constant (Fig. 1) as well as the ratio of the diffusion coefficients of Fe"(EDTA) andNO[3]. 

Zi(Air, x) and 7)(N2, x) are spin-lattice relaxation times of nitroxides in samples equilibrated with atmospheric air and nitrogen, respectively. Note that W(x) is normalized to the sample equilibrated with the atmospheric air. W(x) is proportional to the product of the local translational diffusion coefficient D(x) and the local concentration C(x) of oxygen at a depth x in the membrane, which is in equilibrium with the atmospheric air ... 

Verhallen P.T.H.M., Oomen L.J.P., v.d.Elsen A.J.J.M., Kruger A.J., and Fortuin J.M.H. (1984) The diffusion coefficients of helium, hydrogen, oxygen and nitrogen in water determined from the permeability of a stagnant liquid layer in the quasi-steady state. Chem. Eng. Sci. 39, 1535-1541. 

Due to the extremely low diffusion coefficients in SiC, doping profiles in SiC DMOS transistors must be defined by successive implantation of aluminum (boron) for the base region and nitrogen (phosphorus) for the source. This resulted in a new name for a SiC DMOS transistor double-implanted MOSFET (DIMOSFET). 

We will conserve both nitrogen and oxygen gas. Often, argon is considered to be similar to nitrogen because both are nonreactive and have close to the same diffusion coefficient. Because both gases are volatile, there is no significant resistance on the gas side of the interface, and... 

From this point of view, all the dependencies are explained naturally in a series of mixtures containing helium, oxygen or nitrogen, and bromine, the diffusion coefficient of the hydrogen falls from the first to the last, but the thermal diffusivity falls even more sharply, 0/n grows and, therefore, the... 

Fuller binary diffusion coefficients [9] r. 0.143.10 6r1 75 uij —, 1/2, 1/3. 1/3, pMij (Vj +Vj ) Oxygen Fuller diffusion volume Nitrogen Fuller diffusion volume Hydrogen Fuller diffusion volume Water Fuller diffusion volume 16.3 18.5 6.12 13.1... 

To use this formula, the assumption has been made that the fuel consists of a binary mixture of hydrogen and water, while the cathodic gas is a binary mixture of oxygen and nitrogen. The diffusion coefficient for binary mixtures D y eff is estimated by the equation proposed by Hirschfelder, Bird and Spotz [12], and the Knudsen diffusion coefficient for species i is given by free molecule flow theory [11], Finally, combining Equations (6.15-6.18) the anodic and the cathodic concentration overvoltages are given by (see also Equations (A3.20) and (A3.21)) ... 

This requirement is fulfilled in gas chromatography (GC), where nitrogen or helium is used as the carrier gas. The low density of gases correlates with their high diffusion coefficients, and therefore in GC fast separations at high flow rates can be achieved when compared with LC. In Figure 7.2.1, the diffusion coefficient versus density diagram shows the areas occupied by the mobile phases in HPLC and GC. 

The j -Si3N4 structure exhibits channels parallel to the c-axis which are about 0.5 nm in diameter causing the relative high diffusion coefficient compared to a which do not show such channels (Table 1). These channels are changed into voids with seven nearest nitrogen neighbours in the a structure. 

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