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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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Journal ArticleDOI
TL;DR: In this article, an analytical strategy for simultaneous chemical state identification and quantification of copper and zinc chemical states in complex layered systems is presented based on the curve fitting of the multicomponent X-ray excited Auger spectra.
Abstract: Chemical state identification and quantification based on photoelectron spectra is challenging in the case of copper and zinc and their alloys. In this work an analytical strategy for simultaneous chemical state identification and quantification of copper and zinc chemical states in complex layered systems is presented. This approach is based on the curve fitting of the multicomponent X-ray excited Auger spectra, CuL3M4.5M4.5 and ZnL3M4.5M4.5, that clearly distinguish metallic and oxide components and result in separated ILMM,met and ILMM,ox peak areas. On reference copper and zinc compounds, showing only a single chemical state, the intensity ratio R between photoelectron I2p and Auger intensity ILMM was determined. Rmet was obtained using pure metals and a sputtered brass alloy Cu37Zn. Rox was calculated using the pure oxides. Based on these experimental intensity ratios, R, a quantification factor, k = Rox/Rmet, is calculated for both copper and zinc. This quantification factor k is independent of the instrument employed for the analysis, as proved here by using different spectrometers. The factor k is then used to transfer the experimental Auger intensity ratio (ILMM,met/ILMM,ox) into the I2p,met/I2p,ox intensity ratio, which is required for the quantitative analysis by XPS. The potential of this approach based on XPS and XAES for the patina studies on copper alloys, relevant in various fields including corrosion and cultural heritage, is presented for Cu37Zn model brass alloy after different surface pre-treatments. This approach has proven to be successful.

42 citations

Journal ArticleDOI
B. Angleraud1, N. Mubumbila1, P. Y. Tessier1, V. Fernandez1, Guy Turban1 
TL;DR: In this article, the authors studied the variations of the bonding structure induced by modifying the main deposition parameters, and a systematic characterization of the films by X-ray photoelectron spectroscopy (XPS) was performed.

42 citations

Journal ArticleDOI
TL;DR: In this paper, the compositions of thin Ni-Si films and the chemical states of elements are analyzed by means of X-ray photoelectron spectroscopy (XPS), in view of Pretorius' effective heat of formation (EHF) model.
Abstract: Binary component Ni-Si films of different compositions are fabricated on AISI 304L stainless steels by means of ion-beam sputter (IBS) deposition. The compositions of the thin films and the chemical states of elements are analysed by means of X-ray photoelectron spectroscopy (XPS). The phase formation is studied and discussed in view of Pretorius' effective heat of formation (EHF) model. The proportions of the resulting phases can then be deduced. The electronic structure for the various compositions is also qualitatively investigated from the XPS valence band spectra, suggesting the bonding changes from predominating metallic to covalent bonding in Ni-Si systems when Si content increases.

42 citations

Journal ArticleDOI
TL;DR: In this paper, an alumina-supported CuCr catalyst was examined with the extended x-ray absorption fine-structure (EXAFS) technique, which can determine the chemical states and near-neighbor environments of the separate Cu and Cr atomic species.
Abstract: An alumina‐supported CuCr catalyst was examined with the extended x‐ray absorption fine‐structure (EXAFS) technique. This is a new technique which can determine the chemical states and near‐neighbor environments of the separate Cu and Cr atomic species. Cu was found to occupy both tetrahedral and octahedral sites in the supporting alumina lattice while Cr was found only in octahedral sites. The valence state was Cr+5 in the fresh catalyst which changed to Cr+6 in the exhaust‐cycled material. Confirmation of the valence state assignment was obtained by EPR. Fourier analysis of the EXAFS produced separate radial structure functions for the Cu and Cr atoms since the experiment measures the properties of the individual atomic species rather than those of the structure as a whole. Significant differences were observed by both techniques between fresh and exhaust‐cycled material.

42 citations

Journal ArticleDOI
TL;DR: In situ near edge X-ray absorption fine structure (NEXAFS) spectroscopy was performed to monitor the oxidation state and structure of 4-nm CoPt nanoparticles during the reaction of CO with O2 as mentioned in this paper.

41 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202326
202249
202184
202089
201987
201894