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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, the binding energies of the Si 2p and Si KLL Auger lines for SiO x at x > 0.4 indicate that SiO 2 is predominantly produced.
Abstract: Electronic structures of N 2 + and O 2 + ion-implanted Si(100) (SiN x , SiO x ) have been investigated by means of x-ray photoelectron spectroscopy (XPS), x-ray-induced Auger electron spectroscopy (XAES) and x-ray absorption near-edge structures (XANES). For the O 2 + ion irradiation, the binding energies of the Si 2p and Si KLL Auger lines for SiO x at x > 0.4 show that SiO 2 is predominantly produced. The XANES spectra of SiO x (x > 0.2) at the Si 2p edge are similar to those of bulk SiO 2 . However, other oxides such as SiO are scarcely observed in these spectra. These observations indicate that the SiO x layer consists of a mixture of Si and SiO 2 islands. On the other hand, chemical shift of the Si 2p and Si XLL Auger lines for SiN x becomes larger gradually with the implantation. Thus, it is considered that such changes are due to the stepwise replacement of the Si-Si bond with the Si-N bond. It implies that SiN x has several chemical states of nitride.
12 citations
TL;DR: In this paper, the authors used X-ray photo-electron spectroscopy (XPS) to determine the chemical state of P at grain boundaries, XPS had to be measured for a long time to accumulate the signal from P. The prolonged measurement was possible without contamination by the residual gas because of the high vacuum.
Abstract: Knowledge on the chemical state of phosphorus (P) segregated at grain boundaries in iron is important in discussing the mechanism of grain boundary decohesion by P. In order to determine the chemical state of P at grain boundaries, X-ray photo-electron spectroscopy (XPS) and Auger electron spectroscopy (AES) were used.Fe-P alloy specimens with the P concentration between 0.05mass% and 15.6mass% was fractured in the analyzer chamber of which vacuum was better than 5×10-9Pa(4×10-11torr). Since the amount of P segregated at grain boundaries is small, XPS had to be measured for a long time to accumulate the signal from P. The prolonged measurement was possible without contamination by the residual gas because of the high vacuum. XPS of the segregated P was found to be identical to XPS of P in Fe3P. This result supports the Losch model for the grain boundary decohesion by P, in which a segregated P atom forms a strong bond with surrounding Fe atoms and reduces the strength of bond between Fe atoms neighboring to the P atom.The shape of Auger electron spectrum of P in solid solution varies with the P concentration, but that of the segregated P is independent of the P concentration and identical to that of P in Fe3P. The importance of the variation of the shape of Auger electron spectrum with the P concentration in the quantitative analysis of the segregated P is discussed.
12 citations
TL;DR: In this article, a new concept of chemical state vector is proposed to systematize changes in the electronic parameters of the deposited phase, which is defined as the vector that connects the two extreme points of a Wagner plot dot graph where the BE of photoelectron peaks is represented versus the KE of the Auger peaks for a cation M of a given MO/M'O interface.
Abstract: For certain metal oxides deposited as a thin film on the surface of another oxide, changes may occur in the binding energy (BE) of the photoelectron peaks as well as in the kinetic energy (KE) of the Auger peaks of the deposited cation and consequently in its Auger parameter. These changes are illustrated here for the systems formed by SiO 2 deposited onto TiO 2 and Al 2 O 3 . Shifts by -1.3 and -1.0 eV in the Si 2p BE and by 2.3 and 0.7 eV in the KE of the Si KLL Auger peak are found for these two systems when comparing the values obtained for small amounts of SiO 2 directly interacting with the support with those of a thick film of this material. The different values of these electronic parameters obtained for increasing amounts of SiO 2 can be represented in a Wagner plot. The tendency and magnitude of the changes are similar to those found for Si in phyllosilicate or zeolite compounds with different Si/Al ratios. To systematize these changes in the electronic parameters of the deposited phase the new concept of 'chemical state vector' is proposed. It is defined as the vector that connects the two extreme points of a Wagner plot dot graph where the BE of photoelectron peaks is represented versus the KE of the Auger peaks for a cation M of a given MO/M'O interface. The possibilities and limitations of this concept are discussed with regard to the SiO 2 /TiO 2 and SiO 2 /Al 2 O 3 interface systems reported in this paper and the data for other MO/M'O systems taken from previous works.
12 citations
TL;DR: In this article, the chemical structure of polythiophene films has been investigated using x-ray photoelectron spectroscopy (XPS), and two different methods of doping, coevaporation with FeCl3 and exposure to iodine vapor, are contrasted in this study and several chemical states are observed for the "dopants" associated with these complexes.
Abstract: The chemical structure, including changes in charge distribution upon doping, for vapor‐deposited polythiophene films has been investigated using x‐ray photoelectron spectroscopy (XPS). Two different methods of doping, coevaporation with FeCl3 and exposure to iodine vapor, are contrasted in this study and several chemical states are observed for the ‘‘dopants’’ associated with these complexes. In general, the FeCl3 codeposited complexes have considerably higher conductivities than the iodine exposed films (10–25 S/cm as compared to 0.01 S/cm). Furthermore, besides being a more effective doping mechanism, the FeCl3 codeposited complexes are much more stable upon exposure to atmosphere and also in the ultrahigh vacuum environment of the XPS system. Atomic force microscopy images of the same films show clear morphological differences between the as‐deposited, the FeCl3 codeposited, and the iodine doped films. The as‐deposited film shows a fibrillar‐type structure while the FeCl3 codeposited film is observed ...
12 citations
TL;DR: A process whereby chemical modification of carbon structures with electron withdrawing groups can reveal information, providing accurate, highly refined fitting models far more complex than previously possible is reported.
Abstract: X-ray photoelectron spectroscopy (XPS) is a powerful element-specific technique to determine the composition and chemical state of all elements in an involatile sample. However, for elements such as carbon, the wide variety of chemical states produce complex spectra that are difficult to interpret, consequently concealing important information due to the uncertainty in signal identity. Here we report a process whereby chemical modification of carbon structures with electron withdrawing groups can reveal this information, providing accurate, highly refined fitting models far more complex than previously possible. This method is demonstrated with functionalised ionic liquids bearing chlorine or trifluoromethane groups that shift electron density from targeted locations. By comparing the C 1s spectra of non-functional ionic liquids to their functional analogues, a series of difference spectra can be produced to identify exact binding energies of carbon photoemissions, which can be used to improve the C 1s peak fitting of both samples. Importantly, ionic liquids possess ideal chemical and physical properties, which enhance this methodology to enable significant progress in XPS peak fitting and data interpretation.
12 citations