Showing papers on "Chemical state published in 1977"
TL;DR: In this article, the binding energy of the Zn 2P/sub 3/2/ electron in sludge was found to be 3.5 +- 0.1 on the Pauling scale.
Abstract: Electron Spectroscopy for Chemical Analysis (ESCA) was used to provide information concerning the chemical bonding of zinc and copper present in the sludge obtained from the Dayton, Ohio sewage treatment plant. The binding energy of the Zn 2P/sub 3/2/ electron in sludge when placed under a vacuum of 10/sup -7/ Torr was 1023.8 +- 0.2 eV and the binding energy of the Cu 2p/sub 3/2/ electron in the sludge under similar conditions was 937.2 +- 0.3 eV. These energies are characteristic of both Zn and Cu being in the positive two oxidation state. The electronegativity of the ligand attached to either of these metals was found to be 3.5 +- 0.1 on the Pauling scale. This indicates that Zn and Cu exist in similar compounds, that the ligand binding site is oxygen, and that the possible compounds include carbonate, carboxylate, phosphate, nitrate, silicate, and/or oxide. ESCA, when used in conjunction with other methods, offers excellent potential for more specifically identifying the chemical form of metal in sludge or sludge mixtures.
438 citations
TL;DR: In this article, the electrocatalytic activities of high surface area tungsten carbides for H2 oxidation in acid electrolytes were studied and found to be dependent on the methods of preparation of the carbides.
122 citations
TL;DR: In this article, the experimental situation in connection with theoretical models is discussed, with a special emphasis on the experimental situations of surface magnetization, including dead layers, live layers, surface anisotropy, and magnetic proximity effects.
73 citations
TL;DR: In this paper, the authors illustrate the usefulness of the extended x-ray absorption fine-structure effect for determining the chemical state, structure, and location of adsorbed species.
Abstract: We illustrate the usefulness of the extended x-ray absorption fine-structure effect for determining the chemical state, structure, and location of adsorbed species by a study of 0.2 monolayers of bromine adsorbed on graphite at room temperature. Bromine adsorbs as molecules with one atom fixed above the basal-plane hexagonal site while the molecular axis is free to flop around.
32 citations
25 citations
TL;DR: In this article, it was shown that in the embrittled state these elements are segregated to within the first few monolayers of the high angle boundaries and the segregation is reversible and can be removed by heating at temperatures above the embrittlement range, whilst still within the α field (that is > 600 °C).
Abstract: PREREQUISITES for reversible temper embrittlement of steel1 are the presence of a trace impurity2 (Sb, Sn, As or P) and a major alloying element3,4 (Ni, Cr or Mn). Auger electron spectroscopy (AES) demonstrated that in the embrittled state these elements are segregated to within the first few monolayers of the high angle boundaries5,6. The segregation is reversible and can be removed by heating at temperatures above the embrittlement range, whilst still within the α field (that is > 600 °C). It has been postulated7 that the segregation behaviour can be explained using equilibrium thermodynamics. It is proposed that the trace impurities interact more strongly with the major alloying elements than the Fe matrix and hence the chemical potential of the system is reduced by segregation to the high angle boundaries with the formation of bi-dimensional complexes (such as Ni3Sn2) Mn3P and Cr3P). No experimental evidence is available for the existence of such complexes. AES gives no information regarding the chemical bonding of the segregants but it has been shown8, using X-ray photoelectron spectroscopy (XPS), that the segregated Mn on embrittled fracture surfaces of a 2% Mn steel is in a different chemical state to that on unembrittled surfaces. We report here preliminary results from a specially prepared 3% Ni steel, doped with 119Sn, which were obtained using Mossbauer spectroscopy to monitor changes in the nearest-neighbour atoms of the Sn atoms as a function of heat treatment in the temper embrittlement temperature range.
22 citations
TL;DR: In this paper, the electronic reflectance spectra of palladium-on-alumina catalysts were discussed and information about the chemical state of the palladium in the individual steps of preparation was obtained.
Abstract: The electronic reflectance spectra of palladium-on-alumina catalysts prepared by various procedures from different precursor compounds are discussed. Information is obtained about the chemical state of palladium in the individual steps of preparation.
8 citations
TL;DR: In this paper, it was shown that the 4 1 K(n, a ) 3 · C I reaction in the case of either K 2 S 0 4 or K,SO 0 4 -K 2 BeF 4, lends support to the assumption that decay produced 3 8 CI is sometimes left in sufficient proximity to the oxygen atoms of the original parent sulphate to lead to at least partial recombination.
Abstract: The (β', y) decay of 3 8 S a sa central atom of a sulphate ion leads for the major part to \" C I \" . Depending on the type of sulphate, about 2 1 2 % of the decays lead to the formation of higher oxidation states. The much lower yield of higher oxidation states for 3 CI produced by the 4 1 K(n , a ) 3 · C I reaction in the case of either K 2 S 0 4 or K,SO„ -K 2 BeF 4 , lends support to the assumption that decay produced 3 8 CI (with relatively low recoil energy) is sometimes left in sufficient proximity to the oxygen atoms of the original parent sulphate to lead to at least partial recombination. The probability was calculated that on nuclear recoil f rom the beta-decay of 3 8 S in sulphates the four original bonds with oxygen are preserved to yield 3 8 CIO; This probability was found to be very low in agreement with experimental values.
2 citations