Cobalt, Auger

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. 

Carbon deposition from CO on a cobalt catalyst at low pressures is known to be a structure-sensitive process. CO is adsorbed molecularly on the low index surfaces (Co (0001)), but its dissociation occurs on the Co (1012), Co (1120), and polycrystalline surfaces.5762 Deposition of carbon on Co (1012) and the probable formation of Co3C have been established by Auger emission spectroscopy (AES) and low-energy electron diffraction (LEED) techniques.66... 

Agrawal et al.33 performed studies of Co/A1203 catalysts using sulfur-free feed synthesis gas and reported a slow continual deactivation of Co/A1203 methanation catalysts at 300°C due to carbon deposition. They postulate that the deactivation could occur by carburization of bulk cobalt and formation of graphite deposits on the Co surface, which they observed by Auger spectroscopy. 

Taking the same approach as that described above, Chianelli et al. [72] doped a single crystal of MoS2 with cobalt and equilibrated it at high temperature. Chemical maps made with scanning Auger electron spectroscopy at a spatial... 

Figure 9.21 Auger spectra of cobalt-doped MoS2 crystals taken at a) the basal plane and b) the edge regions (from Chianelli el ul. [72]).

The influence of benzylidene acetone on the electrodeposition mechanism of Zn-Co alloy was investigated [436]. A relationship between corrosion resistance, microstructure, and cobalt content in Zn-Co alloys was investigated [437] using X-ray photoelectron spectroscopy (XPS) and Auger spectroscopy [438]. The role of vitreous carbon, copper, and nickel substrates in Zn-Co deposition from chloride bath was analyzed [439]. 

This study focused on carbon deposits on alununa- and zeolite-supported cobalt catalysts and their effects on CO hydrogenadon. A thermogravimetiic flow system and Auger electron spectrometer were employed to characterize the carbon deposits. 

Figure 5. Auger electron spectroscopy of cobalt exposed to various atmospheres ...

Before discussing these aspects we have to clarify the state of BP on the surface of the positive electrode material. We measured the depth profile of thecobalt positive electrode after 200 cycles by Auger electron spectroscopy (AES), as shown in Fig. 19.18. Thickness of the electroconductive membrane (ECM) film is estimated by the AES depth profiles atomic concentration of cobalt and oxygen. It reaches 90% with and without BP addition as shown in Fig. 19.18. The observed ECM film thicknesses are as follow in the basic electrolyte, the ECM film thickness was 45 A in the functional electrolyte containing 1% of BP, the ECM film thickness was 68 A in the functional electrolyte having 2% of BP, the ECM film thickness was 214 A. These results clearly show that the ECM film thickness on the positive electrode increased with the amount of BP. Based on these results, the cycle life of the basic electrolyte cell should be better, but the cells with the functional electrolyte containing the small amount of BP (the film thickness of 68 A) afford the best results. 

Several authors have investigated the Mossbauer effect for Co-doped cobalt halides and sulphides.Charge states are usually attributed to Auger after-effects, which may or may not be extinguished in a time shorter than the nuclear lifetime. 

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