Search results for "emission spectroscopy"
showing 10 items of 180 documents
Cathodic electrodeposition of ZnCoO thin films
2008
We report on the characterization of ternary Zn1–xCoxO alloy crystalline films grown by electrodeposition onto FTO-coated substrates. The Zn1–xCoxO films have hexagonal wurtzite structure as shown by X-ray diffraction measurements. The Co incorporation into the ZnO lattice is confirmed by the presence of absorption peaks assigned to Co in trigonal crystal field. X-ray photoemission spectroscopy indicates that as-grown films have a considerable concentration of not-fully oxidized metallic Co in the surface that correlates with the O concentration in the surface. Finally, Raman measurements of as-grown films indicate that they are polycrystalline with grains of nanometric size showing short-r…
X-ray photoemission studies of the electronic structure of single-crystalline CdO(100)
2007
The electronic structure of single-crystalline CdO is investigated using X-ray photoemission spectroscopy. The surface is prepared by in situ Ar+ ion bombardment and annealing (IBA). The core level spectra before and after the IBA are presented, and reveal a dramatic reduction in the surface contamination. The semi-core Cd 4d level and valence band region following the IBA are also shown. The surface Fermi level is pinned 1.3 +/- 0.10 eV above the valence band maximum. (c) 2007 Elsevier Ltd. All rights reserved.
Refractory metal reactivity towards oxide surface : W/TiO2(1 1 0) case.
2006
International audience; Reactivity of deposited tungsten towards TiO2(1 1 0) surface was studied using synchrotron radiation photoemission spectroscopy (both core levels, valence band and resonant photoemission) on Materials Science Beamline at ELETTRA. W depositions carried out at room temperature on TiO2(1 1 0) surface give rise to an interfacial reaction which leads to a metastable situation due to kinetic limitations. Annealing induces chemical changes which are function of the initial coverage; for fractional coverage, annealing induces completion of oxidation of deposit whereas reduction to metallic tungsten occurs for highest coverage. These results demonstrate that interaction of W …
Inhibition of Cor-Ten steel corrosion by “green” extracts of Brassica campestris
2018
Abstract Extract of Brassica campestris was tested as potential corrosion inhibitor for Cor-Ten steel in NaCl and acidic solutions, simulating a marine and an urban-industrial environment, respectively. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) were performed both in absence and in presence of the extract at room temperature. The surface chemical analysis was investigated by X-ray Photoemission Spectroscopy (XPS), before and after corrosion. Electrochemical results demonstrated that a very small concentration of Brassica campestris extracts can inhibit Cor-Ten corrosion in NaCl solution (inhibition efficiency of 80–84%) better than in acidic solutions. Su…
Direct observation of half-metallicity in the Heusler compound $Co_{2}MnSi$
2014
Ferromagnetic thin films of Heusler compounds are highly relevant for spintronic applications owing to their predicted half-metallicity, that is, 100% spin polarization at the Fermi energy. However, experimental evidence for this property is scarce. Here we investigate epitaxial thin films of the compound Co2MnSi in situ by ultraviolet-photoemission spectroscopy, taking advantage of a novel multi-channel spin filter. By this surface sensitive method, an exceptionally large spin polarization of () % at room temperature is observed directly. As a more bulk sensitive method, additional ex situ spin-integrated high energy X-ray photoemission spectroscopy experiments are performed. All experimen…
Aging of the surface of an Al-Cr-Fe approximant phase in ambient conditions: Chemical composition and physical properties
2003
ABSTRACTWe have investigated the surface properties of quasicrystalline and approximant phases in the Al-(Cu)-Cr-Fe system upon aging in ambient conditions. We found that some of these properties (like the electrochemical behavior, wetting or friction) slowly evolves with the length of exposure to normal atmospheric conditions, reaching a stable state only after several days. This report essentially focuses on one of these alloys, an Al65Cr27Fe8 approximant phase with g-brass structure. In a first part, we describe the effect of aging on the electrochemical behavior of this alloy and we propose an interpretation based on a simple electrical model of the oxidized surface. In a second part, w…
Structure and chemical bonds in reactively sputtered black Ti–C–N–O thin films
2011
The evolution of the nanoscale structure and the chemical bonds formed in Ti–C–N–O films grown by reactive sputtering were studied as a function of the composition of the reactive atmosphere by increasing the partial pressure of an O2+N2 gas mixture from 0 up to 0.4 Pa, while that of acetylene (carbon source) was constant. The amorphisation of the films observed by transmission electron microscopy was confirmed by micro- Raman spectroscopy, but it was not the only effect associated to the increase of the O2+N2 partial pressure. The chemical environment of titanium and carbon, analysed by X-ray photoemission spectroscopy, also changes due to the higher affinity of Ti towards oxygen and nitro…
Non-linear optical study of hierarchical 3D Al doped ZnO nanosheet arrays deposited by successive ionic adsorption and reaction method
2020
Abstract Successive ionic layer adsorption and reaction (SILAR) method is based on the adsorption and reaction of the ions in the cationic solution and the ionic solution, respectively. This method is simple, inexpensive, large-scale deposition, effective way for deposition on 3D substrates, low-temperature process and represents an easy way for the preparation of doped, composite and heterojunction materials. To take advantage of this method and the ZnO nanostructures, various parameters have been optimized. Undoped and Aluminum (Al) doped ZnO nanostructures were prepared by the SILAR technique. The characterization of the nanostructures prepared was carried out using X-ray diffraction (XR…
Direct determination by portable ED-XRF of mineral profile in cocoa powder samples
2019
Abstract The present study has exploited the rapidity of the analysis and the multi-elemental capability of the energy dispersive X- ray fluorescence (ED-XRF) technique for the mineral profile determination in cocoa powder. A fast, cheap and environmental sustainable method without reagent consumption or toxic waste generation has been proposed. The samples can be prepared in the form of pellets of 13 mm in diameter and 2–3 mm thickness. The different internal calibrations used by ED-XRF equipment did not provide accurate results when comparing the mineral profile with the concentration obtained by Inductively Couple Plasma Optical Emission Spectroscopy (ICP-OES) after microwave assisted di…
Influence of the Chemical Dissolution of MnS Inclusions on the Electrochemical Behavior of Stainless Steels
2005
Immersion of stainless steel containing a well-controlled density of MnS inclusions in 1 M NaCI, pH 3 leads to the chemical dissolution of these heterogeneities. This process was studied using in situ atomic force microscopy and the dissolution rate of MnS inclusions was estimated between 0.01 and 0.19 μm 3 /min. The effects of MnS dissolution on the chemical composition and the local electrochemical behavior of the specimen surface were investigated using secondary ion mass spectroscopy, X-ray photoemission spectroscopy, and the electrochemical microcell technique. It was shown that stable CrS and unstable FeSO 4 were formed. The size of the areas around MnS inclusions affected by the pres…