ESCA studies

Kolb D M, Rath D L, Wille R and Flansen W N 1983 An ESCA study on the electrochemical double layer of emersed electrodes Ber. Bunsenges. Phys. Chem. 87 1108-11 131... 

The catalysts described above had been calcined at 500°C prior to the ESCA studies. Since Mieville (15) reported that it was much easier to reduce catalysts that had been calcined at lower temperatures another series of experiments was performed. 

The effects of tin/palladium ratio, temperatnre, pressnre, and recycling were studied and correlated with catalyst characterization. The catalysts were characterized by chemisorption titrations, in situ X-Ray Diffraction (XRD), and Electron Spectroscopy for Chemical Analysis (ESCA). Chemisorption studies with hydrogen sulfide show lack of adsorption at higher Sn/Pd ratios. Carbon monoxide chemisorption indicates an increase in adsorption with increasing palladium concentration. One form of palladium is transformed to a new phase at 140°C by measurement of in situ variable temperature XRD. ESCA studies of the catalysts show that the presence of tin concentration increases the surface palladium concentration. ESCA data also indicates that recycled catalysts show no palladium sulfide formation at the surface but palladium cyanide is present. 

ESCA studies were also performed on the partially deactivated recycled carbon supported 5%Pd-0.3%Sn catalyst presented in Table 15.3. The sulfur detection limit for this study was -0.5%. Therefore these data implied that there was no obvious Pd-S formation on the used catalyst, but a large amount of nitrogen was present as shown in Table 15.5. We assign this as a possible Pd-CN species. These data suggested that the presence of HCN rather than H2S might be the predominant factor for the deactivation of the catalyst. 

Table VI. ESCA Study of Styrenic-Siloxane Block and Graft Copolymers (Copolymer Composition 10 wt.% PSX)...

The complex azide is highly explosive and must be handled with extreme care. The analogous potassium and caesium derivatives of zinc azide and nickel azide deflagrate strongly in a flame and some are shock-sensitive [1], The potassium salt alone out of 8 azido-complexes exploded during X-irradiation in an ESCA study [2],... 

However, when the reductions were carried out with lithium and a catalytic amount of naphthalene as an electron carrier, far different results were obtained(36-39, 43-48). Using this approach a highly reactive form of finely divided nickel resulted. It should be pointed out that with the electron carrier approach the reductions can be conveniently monitored, for when the reductions are complete the solutions turn green from the buildup of lithium naphthalide. It was determined that 2.2 to 2.3 equivalents of lithium were required to reach complete reduction of Ni(+2) salts. It is also significant to point out that ESCA studies on the nickel powders produced from reductions using 2.0 equivalents of potassium showed considerable amounts of Ni(+2) on the metal surface. In contrast, little Ni(+2) was observed on the surface of the nickel powders generated by reductions using 2.3 equivalents of lithium. While it is only speculation, our interpretation of these results is that the absorption of the Ni(+2) ions on the nickel surface in effect raised the work function of the nickel and rendered it ineffective towards oxidative addition reactions. An alternative explanation is that the Ni(+2) ions were simply adsorbed on the active sites of the nickel surface. 

Lehn, J.-M., Sauvage, J.-R, Ziessel, R., and Hilaire, L., Water photolysis by UV irradiation of rhodium loaded strontium titanate catalysts. Relation between catalytic activity and nature of the deposit from combined photolysis and ESCA studies, Isreal ]. Chem., 22,168,1982. 

ESCA study, 24 134-135 in hydrogenation catalysis, 24 153 infrared spectra, 24 127, 130-131 0 bonding, 24 138-139 S bonding, 24 121 synthesis, 24 144-145 trinuclear clusters... 

The specific surface area of the filler is an important factor which must be taken into consideration during surface treatment. The proportionally bonded surfactant depends linearly on it [74]. ESCA studies carried out on the surface of a CaC03 filler covered with stearic acid have shown that ionic bonds form between the surfactant molecules and the filler surface and that the stearic acid molecules are oriented vertically to the surface [74]. These experiments have demonstrated the importance of both the type of the interaction and the alignment of sur-... 

UV and ESCA studies support the notion that the HOMO of the ylides is primarily a C p orbital, i.e. a nearly pure carbanion. 

Other anionic complexes of beryllium that have been detected are (NH4)2Be(N03)4,141 (NH4)2Be(NCS)4-MeCN and (NH4)2Be(NCS)3-MeCN.142 ESCA studies on beryllium and magnesium complexes of the type [M(NCS)4]2 and [M(CNS)3L] (L = DMF, py, MeCN) are consistent with N-bonding thiocyanate anions being present.142 The structure of K[Be(NH2)3] shows the beryllium to be in a trigonal planar unit.143... 

The nature of the bonding in organogold compounds has been investigated by X-ray diffraction, as well as by a variety of spectroscopic techniques. Mossbauer and ESCA studies have proved particularly informative in determining the oxidation state of the gold center, and vibrational and NMR spectra have been utilized in assigning molecular geometries. 

ESCA studies.72,858 Saunders and Vogel58 have introduced deuteriums into a methyl group of 495 (cation 497) and thereby perturbed the statistical distribution of the otherwise degenerate methyl groups and split the singlet into a doublet. The CD3 group prefers to be attached to the tertiary carbon (498) [Eq. (3.130)]. 

The unsymmetrically bridged ions 506 would be undistinguishable from the symmetrically bridged system 504 in solution NMR experiments. (However, see subsequent discussion of solid-state low-temperature 13C NMR as well as ESCA studies.) It is important to recognize that equilibrating open classical cations 505 cannot explain the NMR data and thus cannot be involved as populated species. 

We have used the ESCA results to provide empirical information about the apparent stoichiometry of sulfate, ammonium, and nitrate ions and other elements and species. Wet chemical analyses performed at several laboratories seemed to contradict some of the conclusions reached from ESCA studies. For example, total reduced nitrogen as determined by ESCA often agrees with the determination of ammonium by wet chemical methods. A consequence of this discrepancy is that in analyses where wet analysis would indicate ammonium sulfate, ESCA would suggest ammonium bisulfate, based on the assumption that particulate Nx species are not associated with sulfate. This assumption may not be valid, because it has been demonstrated QJ that a large fraction of Nx present... 

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