Hydrogen profiling

The use of RBS concurrendy with ERS is necessary for the complete derivation of a hydrogen profile, and it offers some simplifications of analysis. For example, for thin-layer spectra that have been normalized for a common ion fluence Qand solid angle SI, the total yields Y (the areas under the spectral peaks) may be compared in order to derive the layer composition. For... 

Fig. 1. Panel (a) The relative squared sound-speed difference between the Sun and the SSM of Basu et al. (2000). The differences are in the sense (Sun-Model)/Sun. Panel (b) same as Panel (a), but for two solar models, one with mixing below the CZ base and the other without (an SSM). The differences are in the sense (Mixed-SSM)/Mixed. The inset shows the the hydrogen profiles for the two models.

Fig. 5. The hydrogen profile in an Al/Si sample measured with the 15N nuclear reaction, showing hydrogen trapped at the Al/Si interface (Liu et al., 1990).

The reduction of 4 was run in the presence of a series of aryl substituted phosphines. Hydrogenation profiles similar to that shown in Figure 5 were obtained. The rates of hydrogenation of 7 using aliquots... 

A limitation of the above analyses is the absence of hydrogen profiles. Figure 10 shows schematically the importance of hydrogen ions in both the selective dissolution... 

Elastic recoil detection analysis (ERDA) is specifically used for the determination of hydrogen profile in samples. The incident beam is composed of He ions [9],... 

Fig. 2.23. Hydrogen profiles of a-Si H obtained by the nuclear reaction technique, after an anneal at SOO °C. Curves 1 and 2 are calculated assuming different rates of hydrogen desorption from the surface (Reinelt et al. 1983).

Fig. 2.26. Hydrogen profiles of p-type a-Si H comparing hydrogenation of a film exposed to atomic hydrogen at 250 °C, hydrogen-deuterium exchange when the sample is exposed to deuterium, and hydrogen evolution by annealing in vacuum (Street 1987a).

Figure 1 shows the hydrogen and nickel concentration profiles through the reactor as a function of time. Notice the steep hydrogen profile, caused by the infinitely fast reaction between hydrogen and oxygen, which raises the tempera-... 

An industry joint research programme has therefore been conducted at a European scale with the following objectives (i) Numerical simulation of hydrogen profiles in test specimens and reactors (ii) Experimental study of... 

The disbonding tests developed to study the phenomena, which consist of autoclave exposures followed by cooling, are not representative of the actual situation of a reactor. Particularly specimen thicknesses and hydrogen charging conditions are not representative. Numerical calculations are then necessary to estimate the hydrogen profile, both in test specimens and in the wall of the reactor, and to determine if the maximum hydrogen contents obtained in the disbonding test specimens are representative of what can be achieved in the reactor wall. 

For a specimen, the main parameters influencing the hydrogen profile are the cooling rate and the hydrogen pressure. Overlay thickness has only a very slight influence. For a reactor, the main parameter is the base material thickness. The influence of cooling rate is not so important as for test specimens. 

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