XANES

About: XANES is a research topic. Over the lifetime, 7737 publications have been published within this topic receiving 188032 citations.

Molecular orientation dependent interfacial dipole at the F16CuPc∕CuPc organic heterojunction interface

Abstract: In situ synchrotron-based near-edge x-ray absorption fine structure measurements and photoemission spectroscopy have been used to investigate the effect of molecular orientation on the interfacial dipole and the energy level alignment at the interfaces of organic heterojunctions comprising copper-hexadecafluoro-phthalocyanine (F16CuPc) on both standing-up and lying-down copper(II) phthalocyanine (CuPc) thin films. It is found that F16CuPc thin films adopt the same molecular orientation of the underlying CuPc thin films. An interfacial dipole of 0.45eV forms at the interface of lying-down F16CuPc∕CuPc on highly ordered pyrolytic graphite. In contrast, a much larger interfacial dipole of 1.35eV appears at the interface of standing-up F16CuPc∕CuPc on octane-1-thiol terminated Au(111).

Further Understanding of the Electronic Interactions between N719 Sensitizer and Anatase TiO2 Films: A Combined X-ray Absorption and X-ray Photoelectron Spectroscopic Study

Abstract: In this study, the electronic properties of N719 adsorbed onto anatase were comparably investigated by using X-ray absorption spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS) techniques. Sensitized TiO2 films made from two different nanocrystalline anatase powders were investigated: a commercial one (Solaronix) and our synthetic variety produced through aqueous synthesis. This was done to investigate how our aqueous-produced nanocrystalline anatase substrates compared with commercial products and to observe whether both nanocrystalline anatase anodes behaved in a similar manner in terms of their bonding and electronic interactions. Surface coordination changes to Ti−O groups previously reported via Ti K-edge extended X-ray absorption fine structure (EXAFS) data [using transmission or fluorescence yield (FY)] between the pure TiO2 and the adsorbed state were not observed in our measurements via the Ti L or K X-ray absorption near-edge structure (XANES) (nor EXAFS) data for both substrates via ...

Nickel K-edge x-ray absorption fine structure of lithium nickel oxides

Abstract: Lithium nickel oxides, Li[sub x]Ni[sub 1[minus]x]O, with the lithium content x varying from 0.40 (close to the maximum value of 0.5) to 0 have been studied by using nickel K-edge X-ray absorption fine structure (XAFS) spectroscopy. The XANES (X-ray absorption near-edge structure) shows several distinct features whose energy and intensity evolve smoothly as a function of x. Quantitative analysis of the EXAFS (extended XAFS) data conclusively showed the presence of systematic structural trends with lithium content, x. In particular, we observed two different Ni-O bond lengths (2.07(1) and 1.94(1) A) with proportions changing with x and systematic variations (with x) of the outer-shell Ni-Ni distances. Overall, the structural trends deduced from the XAFS data were found to be more consistent with an increased nickel oxidation state (Ni[sup +] to Ni[sup +]) with increasing x rather than with an increased oxygen oxidation state (O[sup 2[minus]] to O[sup [minus]]), although the true pictures lies between these two extremes. 37 refs., 11 figs., 4 tabs.

Spectroscopy of π bonding in hard graphitic carbon nitride films: Superstructure of basal planes and hardening mechanisms

Abstract: X-ray-absorption near-edge spectroscopy (XANES or NEXAFS) has been used to obtain information on the orientation, corrugation, and cross-linking of graphitic carbon nitride planes, structural parameters that determine the mechanical properties of the material. The contribution of p electrons from carbon and nitrogen atoms to \ensuremath{\pi} bonding in graphitic carbon nitride has been studied with elemental and angular sensitivity by XANES. The density of ${\ensuremath{\pi}}^{*}$ states from nitrogen is composition dependent and presents angular anisotropy, while the density of ${\ensuremath{\pi}}^{*}$ states from carbon is isotropic and independent of composition. Both observations are consistent with a model of the superstructure of basal planes.

Quantitative Analysis of Ti−O−Si and Ti−O−Ti Bonds in Ti−Si Binary Oxides by the Linear Combination of XANES

Abstract: X-ray absorption near edge structure (XANES) of Ti K-edge of Ti−Si mixed oxides and titania supported on silica with various Ti contents was studied to investigate the fractions of Ti−O−Si and Ti−O−Ti bonds quantitatively by fitting the preedge of Ti K-edge with the linear combination of two reference XANES spectra. In mixed oxides, the fraction of Ti−O−Ti was increased up to 0.55 when Ti/Si was varied from 0.04 to 0.5. The greatest change of each fraction occurred around 0.15−0.2 of Ti/Si, which was coincident with the formation of anatase titania as observed by XRD. For titania supported on silica with a surface area of 300 m2 g-1, the preedge fitting results combined with XRD and XPS indicated that monolayer coverage was reached around 7−10 wt % Ti loading where the amount of Ti in Ti−O−Si was saturated to 0.56 mmol-Ti/g-material. This work demonstrated the possibility of the quantification of Ti−O−Si and Ti−O−Ti bonds in Ti−Si binary oxides by using the linear combination of reference XANES spectra. K...