Towards atomic resolution in sodium titanate nanotubes using near-edge X-ray-absorption fine-structure spectromicroscopy combined with multichannel multiple-scattering calculations

Recent advances in near-edge X-ray-absorption fine-structure spectroscopy coupled with transmission X-ray microscopy (NEXAFS–TXM) allow large-area mapping investigations of individual nano-objects with spectral resolution up to E/ΔE = 104 and spatial resolution approaching 10 nm. While the state-of-the-art spatial resolution of X-ray microscopy is limited by nanostructuring process constrains of the objective zone plate, we show here that it is possible to overcome this through close coupling with high-level theoretical modelling. Taking the example of isolated bundles of hydrothermally prepared sodium titanate nanotubes ((Na,H)TiNTs) we are able to unravel the complex nanoscale structure from the NEXAFS–TXM data using multichannel multiple-scattering calculations, to the extent of being able to associate specific spectral features in the O K-edge and Ti L-edge with oxygen atoms in distinct sites within the lattice. These can even be distinguished from the contribution of different hydroxyl groups to the electronic structure of the (Na,H)TiNTs.

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On the influence of multiple scattering contributions to the extended X-ray absorption fine structure (EXAFS) spectra of the photosystem II manganese complex

Berichte der Bunsengesellschaft für physikalische Chemie ◽

10.1002/bbpc.19961001211 ◽

1996 ◽

Vol 100 (12) ◽

pp. 1993-1998 ◽

Cited By ~ 4

Author(s):

Jens Dittmer ◽

Holger Dan

Keyword(s):

Fine Structure ◽

Photosystem Ii ◽

Multiple Scattering ◽

Manganese Complex ◽

X Ray ◽

Absorption Fine ◽

X Ray Absorption ◽

Exafs Spectra

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Extended X-ray absorption fine structure and multiple-scattering simulation of nickel dithiolene complexes Ni[S2C2(CF3)2]2n(n= −2, −1, 0) and an olefin adduct Ni[S2C2(CF3)2]2(1-hexene)

Journal of Synchrotron Radiation ◽

10.1107/s1600577514025041 ◽

2015 ◽

Vol 22 (1) ◽

pp. 124-129 ◽

Cited By ~ 4

Author(s):

Weiwei Gu ◽

Hongxin Wang ◽

Kun Wang

Keyword(s):

Fine Structure ◽

Multiple Scattering ◽

Edge Structure ◽

X Ray ◽

Absorption Fine ◽

Square Planar ◽

Square Planar Complexes ◽

Uv Visible ◽

Edge Features ◽

X Ray Absorption

A series of Ni dithiolene complexes Ni[S2C2(CF3)]2n(n= −2, −1, 0) (1,2,3) and a 1-hexene adduct Ni[S2C2(CF3)2]2(C6H12) (4) have been examined by NiK-edge X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine-structure (EXAFS) spectroscopies. Ni XANES for1–3reveals clear pre-edge features and approximately +0.7 eV shift in the NiK-edge position for `one-electron' oxidation. EXAFS simulation shows that the Ni—S bond distances for1,2and3(2.11–2.16 Å) are within the typical values for square planar complexes and decrease by ∼0.022 Å for each `one-electron' oxidation. The changes in NiK-edge energy positions and Ni—S distances are consistent with the `non-innocent' character of the dithiolene ligand. The Ni—C interactions at ∼3.0 Å are analyzed and the multiple-scattering parameters are also determined, leading to a better simulation for the overall EXAFS spectra. The 1-hexene adduct4presents no pre-edge feature, and its NiK-edge position shifts by −0.8 eV in comparison with its starting dithiolene complex3. Consistently, EXAFS also showed that the Ni—S distances in4elongate by ∼0.046 Å in comparison with3. The evidence confirms that the neutral complex is `reduced' upon addition of olefin, presumably by olefin donating the π-electron density to the LUMO of3as suggested by UV/visible spectroscopy in the literature.

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