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Chemical state
About: Chemical state is a research topic. Over the lifetime, 2378 publications have been published within this topic receiving 78183 citations.
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TL;DR: In this article, a temperature-programmed photoelectron emission (TPPE) was used to characterize the state of real metal surfaces in ambient environments, and the number of emitted electrons in a PE spectrum (PE total count) was investigated for 17 kinds of rolled metal sheets that were cleaned in acetone.
Abstract: To easily characterize the state of real metal surfaces in ambient environments, we have developed an extremely sensitive technique for the surface analysis using photoelectron emission phenomena depending on temperature. We call this method temperature programmed photoelectron emission (TPPE). The emitted electrons were detected by a gas-flow Geiger counter with Q gas. A PE spectrum representing the curve of the PE intensity vs. wavelength was obtained at different temperatures in the temperature-increase and subsequent temperature-decrease process between 25 and 350°C. The number of emitted electrons in a PE spectrum (PE total count) as a function of the measurement temperature was investigated for 17 kinds of rolled metal sheets that were cleaned in acetone. The metals were distinctly classified into five groups A-I (Al, Pt, Pb), A-II (Ag, Cu, Au, Ni), B-III (Ta), B-IV (Pd, W, Ti, Mo), and B-V (Nb, Fe, Zn, Co, Sn). The A groups indicated a temperature dependent PE total count, while the B groups indicated a virtually temperature independent PE total count. With the A groups a greater amount of the adsorbed oxygen that was present on the initial surface was found by XPS to change to oxide oxygen after TPPE measurement, with the exception of Al. This chemical change is suggested to play a substantial role in the temperature dependence of the PE total count. With the B groups oxide oxygen existed predominantly on the initial surface, resulting in little change in the chemical state of the oxygen. It is suggested that the ability of the metals in gas chemisorption is closely related to the TPPE behavior.
5 citations
TL;DR: In this article, a commercial Ce-W cathode was selected as research object and the cathode working environment was simulated by heating in an ultra-high vacuum (UHV) chamber.
5 citations
TL;DR: In this paper, highly oriented CuSbS2 thin films have been prepared by annealing layered structures of chemical bath deposited Sb2S3 and thermal evaporated Cu, followed by rapid thermal processing (RTP).
5 citations
TL;DR: In this article, a quantitative approach to AES is illustrated for various metal-sulfur compounds involving: (a) intensity measurements via integral areas of background subtracted N(E) spectra (including sample probe potential biasing to improve background subtraction); (b) low primary electron dose, pulse-count spectrum acquisition to minimize primary electron beam damage and charging artifacts; (c) corrections to spectral intensity for variations in electron backscattering and inelastic Auger electron mean free path for each metal sulfate compound matrix; XPS quantitative analysis to correct for differences in surface
Abstract: A quantitative approach to AES is illustrated for various metal–sulfur compounds involving: (a) intensity measurements via integral areas of background subtracted N(E) spectra (including sample probe potential biasing to improve background subtraction); (b) low primary electron dose, pulse-count spectrum acquisition to minimize primary electron beam damage and charging artifacts; (c) corrections to spectral intensity for variations in electron backscattering and inelastic Auger electron mean free path for each metal–sulfur compound matrix; (d) XPS quantitative analysis to correct for differences in surface vs. bulk stoichiometries. Although the above approach results in improved analytical precisions, a residual difference of greater than a factor of 2 remains in the Auger elemental sensitivity factor for sulfur (LMM) in corresponding metal sulfate vs. sulfide compounds. This suggests a chemical state dependent Auger electron yield (core level ionization cross section times the Auger transition probability). Accurate AES quantification, therefore, may require chemical state specific sensitivity factors, particularly for valence shell transitions.
5 citations
TL;DR: In this article, the evolution of a 2 ML Au rectangular patch deposited on a surface containing three-dimensional Ag islands was studied by scanning photoemission microscopy, the surface composition and electronic structure of the Au patch and of the transition region between the patch and the Au-free Ag/Si area were characterized on a submicron scale at room temperature and after annealing at various temperatures up to 993 K.
Abstract: The evolution of a 2 ML Au rectangular patch deposited on a surface containing three-dimensional Ag islands was studied by scanning photoemission microscopy. The surface composition and electronic structure of the Au patch and of the transition region between the patch and the Au-free Ag/Si area were characterized on a submicron scale at room temperature and after annealing at various temperatures up to 993 K. The spatial expansion of the Au patch due to Au surface diffusion and the chemical state of Ag and Au in the different interface zones were examined by chemical mapping and by analysis of the Ag 3d and Au 4f core level and valence band spectra, taken at selected spots of the surface, From the analysis of the Au 4f core level line shape, we identified a chemical state for Au at the forefront of the Au migration on the surface and assigned it to an adsorption site on top of Si trimers. This was the dominating Au species for low (< 0.2 ML) Au coverages, Following the evolution of the Au patch upon annealing we discovered substantial differences in its composition and structural changes compared to a continuous 2 ML Au film deposited on a surface. The important role of the Ag and Au surface diffusion in the evolution of an interface containing compositional discontinuities was discussed.
5 citations