Total hydrogen, determination

As with RBS, the simplest and most precise measurement that ERS can provide is the absolute measure of total hydrogen content ( H and/or H) within a surface layer or film of thickness less than a few thousand angstroms. When the layer is thin, this is determined from the total number of events, or yield Ysummed over the elastic recoil spectral peak. The yield may be expressed as... 

Hydrogenation was carried out with the assistance of an n-butyl lithium/cobalt octoate catalyst (6). It was necessary to determine the proper conditions for efficTent hydrogenation with minimal degradation (7). For the BIB polymer the Li/Co ratio used was 5/1 to obtain selective hydrogenation of the polybutadiene, while for the total hydrogenation of the BBB polymer, a ratio of 2.2/1 was satisfactory. NMR analysis showed better than 99% hydrogenation. 

The total hydrogen content in an a-Si H film is determined by the details of the deposition process. The step in the deuterium concentration at the interface between two different boron doped a-Si H films (10 2 B2H6 in SiH4) grown at 270°C and 150°C respectively persists, even after annealing at 225°C for several hours... 

For each coal, at the maximum in hydrogen content, or H/C atomic ratio, the aliphatic hydrogen content (determined by H NMR analysis) accounted for over 90% of the total hydrogen. The aliphatic hydrogen contents were 10.5% for the subbituminous coal,PSOC-1403, and 6.9% for the bituminous coal, PSOC-1266. The high aliphatic hydrogen content was associated with the presence of polymethylene chains. The early release of paraffinic material, as n-alkanes and as long chain substituents to aromatic structures, under conditions of mild pyrolysis has been observed in other research (13-15. ... 

Total hydrogen also is determined by catalytic burning of a sample in oxygen It) form water. The water is absorbed in a desiccant and weighed directly. Hydrogen results as determined include the hydrogen present in both the sample moisture and water of hydration. 

Nuclear magnetic resonance spectroscopy has proved to be of great value in fossil fuel research because it allows rapid and nondestructive determination of the total hydrogen content and distribution of hydrogen among the chemical functional groups present (Bartle and Jones, 1978 Retcofsky and Link, 1978 Petrakis and Edelheit, 1979 Snape et al., 1979 Davidson, 1980, 1986 Miknis, 1982, 1988 Calkins and Spackman, 1986 Cookson and Smith, 1987 Bartle,... 

Muraca, R. F., Willis, E., Martin, C. H., Chrutchfield, C. A. Determination of water in nitrogen tetroxide Gas chromatographic method for total hydrogen content. 

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