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, a near-edge X-ray absorption fine structure (NEXAFS) was used to establish the CO bond length (1.25±0.05 A ) and the OCO angle (124±15°) and the azimuthal orientation (along [1 1 0]) of the molecular plane of the formate catalytic intermediate adsorbed on Cu(110), and the adsorption site (atop copper atoms in the top (ridge) rows, with oxygen atoms
92 citations
TL;DR: A combined density functional theory and experimental study of the O1s binding energies and X-ray Absorption Near Edge Structure of a variety of oxygen species on Ag(111) and Ag(110) surfaces yields unique spectroscopic fingerprints, allowing us to show that unreconstructed atomic oxygen is likely not present on either surface under equilibrium conditions at oxygen chemical potentials typical for ethylene epoxidation.
Abstract: We report on a combined density functional theory and the experimental study of the O1s binding energies and X-ray Absorption Near Edge Structure (XANES) of a variety of oxygen species on Ag(111) and Ag(110) surfaces. Our theoretical spectra agree with our measured results for known structures, including the p(N × 1) reconstruction of the Ag(110) surface and the p(4 × 4) reconstruction of the Ag(111) surface. Combining the O1s binding energy and XANES spectra yields unique spectroscopic fingerprints, allowing us to show that unreconstructed atomic oxygen is likely not present on either surface under equilibrium conditions at oxygen chemical potentials typical for ethylene epoxidation. Furthermore, we find no adsorbed or dissolved atomic species whose calculated spectroscopic features agree with those measured for the oxygen species believed to catalyze the partial oxidation of ethylene.
91 citations
TL;DR: In this paper, soft X-ray (200 to 1000 eV) absorption spectroscopy at the O K-edge and the metal L II,III -edges, in both the fluorescence yield (FY) and the partial electron yield (PEY) mode, has been used to probe the electronic structure of electrochemically deintercalated Li 1-x Ni 05 Mn 05 O 2
Abstract: Soft X-ray (200 to 1000 eV) absorption spectroscopy at the O K-edge and the metal L II,III -edges, in both the fluorescence yield (FY) and the partial electron yield (PEY) mode, has been used to probe the electronic structure of electrochemically deintercalated Li 1-x Ni 05 Mn 05 O 2 FY and PEY spectra of the transition metal L II,III -edges, indicated that Mn ions remain mostly unchanged in the Mn 4+ state at all levels of charge However, the Ni FY L-edge spectra show a continuous shift to higher energy during charge, but remain mostly unchanged in the PEY data The results of the FY data show that the Ni ions in the bulk are oxidized form Ni 2+ to Ni 4+ during charge The difference between the surface-sensitive PEY data and the bulk-sensitive FY data indicates that the surface of Li 1-x Ni 05 Mn 05 O 2 has a different electronic structure than the bulk The shift in the O K-edge to lower energies and the development of a shoulder on the low energy side of the first pre-edge peak indicates that the holes compensating the lithium ion deintercalation are located in O 2p states as well as Ni 3d states These results show that soft X-ray absorption is a powerful technique for studying the electronic structure of new battery materials and it provides unique complementary information to that obtained from hard X-ray (above 1000 eV) absorption studies at the transition metal K-edges
91 citations
TL;DR: In this paper, the adsorption of alanine on Cu{1/1/0} was studied by a combination of near edge X-ray absorption fine structure (NEXAFS) spectroscopy, Xray photoelectron spectroscopic (XPS) and density functional theory (DFT).
91 citations
TL;DR: In this paper, the first systematic study of the hydrothermal synthesis of the manganites La0.5M 0.5Ba 0.9160, La 0.4S 0.7353, and La 1.5N 0.443 was presented.
Abstract: We present results of the first systematic study of the hydrothermal synthesis of the manganites La0.5M0.5MnO3
(M = Ca, Sr, Ba), and a detailed characterisation of the products using a number of experimental methods. All three materials can be produced as phase-pure, polycrystalline powders in one step from solutions of metal salts in aqueous potassium hydroxide solution at temperatures of 240 °C for M = Sr or Ba and 270 °C for M = Ca. Iodometric titration and Mn K-edge X-ray absorption near edge spectroscopy (XANES) combined with elemental analysis for metals confirms the average manganese oxidation state as 3.5 in each of the materials. Scanning electron microscopy shows that the materials are made up of cube-shaped particles 1 µm in dimension for La0.5Ba0.5MnO3, 10 µm on average for La0.5Sr0.5MnO3 and 20 µm for La0.5Ca0.5MnO3. La0.5Ba0.5MnO3 is shown to adopt an A-site ordered perovskite structure (tetragonal, P4/mmm, a
= 3.9160(1)
A, c
= 7.8054(2)
A); this is determined using powder neutron diffraction, thermogravimetric analysis and magnetisation measurements. High-resolution powder neutron diffraction data from La0.5Sr0.5MnO3 show that the material adopts a distorted perovskite structure (tetragonal, I4/mcm, a
= 5.44778(40)
A, c
= 7.7353(10)
A) similar to that previously reported for materials of the same composition prepared by a solid-state route. Hydrothermal La0.5Ca0.5MnO3 adopts an orthorhombic perovskite structure (Pnma, a
= 5.410(1)
A, b
= 7.604(1)
A, c
= 5.443(2)
A). Finally, we examine poorly ordered precursors of La0.5Ba0.5MnO3, formed prior to the crystallisation of the perovskite, using Mn K-edge X-ray absorption fine structure spectroscopy. This shows that at the earliest stage of the reaction the manganese is found in an oxidation state of 3.5 in edge-shared octahedral sites, consistent with the formation of a K0.5MnO2·nH2O, birnessite-like phase before the formation of the perovskite.
91 citations