Sulfur depth profiles

The Auger depth profile obtained from a plasma polymerized acetylene film that was reacted with the same model rubber compound referred to earlier for 65 min is shown in Fig. 39 [45]. The sulfur profile is especially interesting, demonstrating a peak very near the surface, another peak just below the surface, and a third peak near the interface between the primer film and the substrate. Interestingly, the peak at the surface seems to be related to a peak in the zinc concentration while the peak just below the surface seems to be related to a peak in the cobalt concentration. These observations probably indicate the formation of zinc and cobalt complexes that are responsible for the insertion of polysulfidic pendant groups into the model rubber compound and the plasma polymer. Since zinc is located on the surface while cobalt is somewhat below the surface, it is likely that the cobalt complexes were formed first and zinc complexes were mostly formed in the later stages of the reaction, after the cobalt had been consumed. 

Fig. 42. AES depth profiles of copper and sulfur (top) and zinc and oxygen (bottom) for the brass-on-glass adhesion specimens as a function of curing temperature. Reproduced by permission of Gordon and Breach Science Publishers from Ref. [46].

An ESCA angular depth profile study of similarly treated t-PB showed that sulfur and nitrogen are surface species. 

Fig. 4.49 Composition depth profiles of the (001) plane of two Pt-44.8 at.% Rh alloys, one containing sulfur impurity and one not. Note the reversal of the enriched species, in both the top and the second layers.

Figure 9.21 Depth profiling of phosphorus and sulfur in protein spots of a 2D gel measured by LA-ICP-MS. Transient signals show decreasing ion intensity with increasing replication number (proportional to measurement time).

FIGURE 3 Depth profiles for 14C age and sulfur-to-carbon (S/C) ratios for fulvic acid samples isolated from Lake Fryxell, a permanently ice-covered lake in the McMurdo Dry Valleys, Antarctica (from Aiken et al., 1996). In the upper water column, the fulvic acids have a modern signal. This young fulvic acid derives from perennial algal mats in glacial meltwater streams. At depth, the fulvic acids are quite old (about 3000 years) and are possibly derived from organic material in sediments. The ratio of S/C increases with depth as conditions in the water column become anoxic. 

The concentrations of the total alkylthiophenes (except thiophene hopanoids) in the bitumens show a depth profile somewhat similar to that of the total sulfur content (cf. Figures 6a and Id). The high concentrations of alkylthiophenes in Facies B compared to A and C are consistent with the proposed incorporation of inorganic sulfur species into specific funtionalised lipids in anoxic marine environments (6-12). 

Figure 9. (a) Depth profiles of C37 and C38 mid-chain 2,5-dialkylthiophenes XI for the Jurf ed Darawish oil shale, (b) Formation of C37 and C38 mid-chain 2,5-dialkylthiophens XI by sulfur (H2S) incorporation into triunsaturated C37 and C38 methylketones IX or hydrocarbons X. 

Auger electron spectroscopy (AES) is particularly suited for surface analysis (depth 0.5-1 nm). AES depth profile analysis was employed to determine the thickness and composition of surface reaction layers formed under test conditions in the Reichert wear apparatus in the presence of four different ZDDPs additives at different applied loads (Schumacher et al., 1980). Using elemental sensitivity factors the concentration of the four elements (S, P, O, C) was determined at three locations corresponding to a depth of 1.8, 4.3, and 17 nm. No significant correlation between wear behavior and carbon or oxygen content of the reaction layer was observed. A steady state sulfur concentration is reached after a very short friction path. Contrary to the behavior of sulfur, phosphorus concentration in the presence of ZDDPs increases steadily with friction path, and no plateau value is reached. 

Figure 9 (a) Depth profiles for total Mo/Al ratios and wt.% pyrite sulfur (Spy) for both oxic and euxinic sediments spanning the most recent glacial-interglacial transition in the... 

Sulfur speciation In the porewaters of two salt marshes (Great Marsh, Delaware and Great Slppewlssett, Cape Cod, Massachusetts) are presented. A major finding Is that the porewaters from Great Slppewlssett salt marsh are dominated by Inorganic sulfur species throughout the depth profile. 

In the Massachusetts marsh, only inorganic sulfide and thiosulfate occur as the major reduced forms of sulfur over the depth profile. Although this could be related to a lack of sulfide oxidation, sulfate depletion is not very high in this core. Therefore, neither process is the more dominant biogeochemical process. Previous studies(ip, ) have not found evidence for thiols in this marsh even when sulfide oxidation was prevalent, addition, cores were prepared from this marsh for controlled microcosm experiments. In cores in which oxidation was Induced, thiols were not detected in the porewaters. 

Fig. 21 Depth profiles of a an unheated P3OT/C60 bilayer device and b a PSOT/Cao bilayer device heated at 130 °C. The concentrations of sulfur (solid lines), indium (dotted lines), and oxygen (dashed lines) were monitored. The arrow indicates the position of the P3OT/C60 interface as determined from absorption measurements. The unheated bilayer shows a rather sharp interface between P30T and 50 For the interdiffused film, the P30T concentration rises slowly throughout more than 100 nm (from 35 to 150 nm) of the bulk of the film. (Reprinted with permission from [133], 2005, American Institute of Physics)...

Fig. 8.13 Concentration versus depth profiles of organic carbon total sulfur and Fe/Al ratio (mol/g Fe...

A special case in the modern ocean sulfur isotope distribution is the isotopic composition of hydrogen sulfide in anoxic basins. Fry et al. (1991) compared depth profiles of the Black Sea and the... 

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