Topic
XANES
About: XANES is a research topic. Over the lifetime, 7737 publications have been published within this topic receiving 188032 citations.
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TL;DR: In this article, the formation of sp 2 -bonded Boron carbonitride (BCN) phase was confirmed by Fourier transform infrared spectroscopy, which showed that B atoms were bonded to C and N atoms to form the BCN atomic hybrid configurations.
56 citations
TL;DR: In this paper, the changes in the XANES ranging 10-15 eV above the absorption edge are interpreted based on the known band-structure calculations, which are related to the multiple-scattering processes (EXAFS) at the nearest atoms.
56 citations
TL;DR: Results of an X-ray absorption spectroscopy investigation into the mechanism of the carbon-supported Pt-Ru nanoparticles (NPs) formation process support the Pt-rich core and Ru-rich shell structure with a considerable amount of segregation in the Pt region and with lessgregation in the Ru region for the obtained Pt- Ru/C NPs.
Abstract: The understanding of the formation mechanism of nanoparticles is essential for the successful particle design and scaling-up process This paper reports findings of an X-ray absorption spectroscopy (XAS) investigation, comprised of X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) regions, to understand the mechanism of the carbon-supported Pt-Ru nanoparticles (NPs) formation process We have utilized Watanabe's colloidal reduction method to synthesize Pt-Ru/C NPs We slightly modified the Watanabe method by introducing a mixing and heat treatment step of Pt and Ru oxidic species at 100 °C for 8 h with a view to enhance the mixing efficiency of the precursor species, thereby one can achieve improved homogeneity and atomic distribution in the resultant Pt-Ru/C NPs During the reduction process, in situ XAS measurements allowed us to follow the evolution of Pt and Ru environments and their chemical states The Pt L III -edge XAS indicates that when H 2 PtCl 6 is treated with NaHSO 3 , the platinum compound is found to be reduced to a Pt(II) form corresponding to the anionic complex [Pt(SO 3 ) 4 ] 6- Further oxidation of this anionic complex with hydrogen peroxide forms dispersed [Pt(OH) 6 ] 2- species Analysis of Ru K-edge XAS results confirms the reduction of Ru III Cl 3 to [Ru II (OH) 4 ] 2- species upon addition of NaHSO 3 Addition of hydrogen peroxide to [Ru II (OH) 4 ] 2- causes dehydrogenation and forms RuO x species Mixing of [Pt(OH) 6 ] 2- and RuO x species and heat treatment at 100 °C for 8 h produced a colloidal sol containing both Pt and Ru metallic as well as ionic contributions The reduction of this colloidal mixture at 300 °C in hydrogen atmosphere for 2 h forms Pt-Ru nanoparticles as indicated by the presence of Pt and Ru atoms in the first coordination shell Determination of the alloying extent or atomic distribution of Pt and Ru atoms in the resulting Pt-Ru/C NPs reveals that the alloying extent of Ru (J Ru ) is greater than that of the alloying extent of Pt (J Pt ) The XAS results support the Pt-rich core and Ru-rich shell structure with a considerable amount of segregation in the Pt region and with less segregation in the Ru region for the obtained Pt-Ru/C NPs
56 citations
TL;DR: In this article, a solution based synthesis of epitaxial thin films of neptunium oxide and plutonium oxide is reported. But the performance of these films is limited due to the high melting point of actinide oxides and their inherent radioactivity.
Abstract: We report a solution based synthesis of epitaxial thin films of neptunium oxide and plutonium oxide. Actinides represent a challenge to first principle calculations due to features that arise from f orbital interactions. Conventional semi-local density functional theory predicts NpO2 and PuO2 to be metallic, when they are well known insulators. Improvements in theory are dependent on comparison with accurate measurements of material properties, which in turn demand high-quality samples. The high melting point of actinide oxides and their inherent radioactivity makes single crystal and epitaxial film formation challenging. We report on the preparation of high quality epitaxial actinide films. The films have been characterized through a combination of X-ray diffraction and X-ray absorption fine structure (XANES and EXAFS) measurements. We report band gaps of 2.80 ± 0.1 eV and 2.85 ± 0.1 eV at room temperature for PuO2 and NpO2, respectively, and compare our measurements with state-of-the-art calculations.
56 citations
TL;DR: The XANES spectrum of a DNA sample with a known ratio of the polyn nucleotides is equivalent to the weighted sum of the spectra of individual polynucleotides, indicating that the difference in base stacking interactions produces negligible spectral effects.
56 citations