Nitrogen atoms concentration profile

Figure 11. Carbon, oxygen and nitrogen atomic concentration depth profile for C-PA (open symbols) and PAO (solid ones) membranes...

Prompt NO mechanisms In dealing with the presentation of prompt NO mechanisms, much can be learned by considering the historical development of the concept of prompt NO. With the development of the Zeldovich mechanism, many investigators followed the concept that in premixed flame systems, NO would form only in the post-flame or burned gas zone. Thus, it was thought possible to experimentally determine thermal NO formation rates and, from these rates, to find the rate constant of Eq. (8.49) by measurement of the NO concentration profiles in the post-flame zone. Such measurements can be performed readily on flat flame burners. Of course, in order to make these determinations, it is necessary to know the O atom concentrations. Since hydrocarbon-air flames were always considered, the nitrogen concentration was always in large excess. As discussed in the preceding subsection, the O atom concentration was taken as the equilibrium concentration at the flame temperature and all other reactions were assumed very fast compared to the Zeldovich mechanism. 

Figures 25—27 show the temperature and composition profiles calculated for the standard flame by the refined treatment using set 2 of the rate coefficients of Table 30. Figure 25 also includes for comparison a number of points representing the observed temperature profile. Agreement is excellent. The composition profiles for the stable species in the flame were measured by means of a mass spectrometric probe, using the unbumt gas ratios of each species concentration to that of nitrogen as calibration standards. Realistic comparison is then in terms of these ratios, and is shown in Fig. 28. The relative intensities of sodium chemiluminescence in the recombination region of the low temperature flames are proportional to the square of the H atom concentrations. A comparison between theory and experiment on this basis, with intensities normalized with respect to the maximum H atom concentration and the...

One technique that has been able to measure hydrogen concentration in a thin film and do a depth profile, without reliance on standards, uses a resonant nuclear reaction technique.16 In this procedure, the nuclear reaction between a hydrogen atom ( H) and an energetic nitrogen-15 atom (1SN) is used. That is... 

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