Next-near-neighbour interactions with Al in Li+- and Rb+-exchanged Na+β-aluminas, detected by synchrotron X-ray absorption spectroscopy

2000 ◽  
Vol 33 (2) ◽  
pp. 234-242 ◽  
Author(s):  
Augusto Marcelli ◽  
Annibale Mottana ◽  
Giannantonio Cibin
Keyword(s):  
Xanes Spectrum ◽  
Near Neighbour ◽  
Edge Structure ◽  
X Ray ◽  
Local Environments ◽  
Composition And Structure ◽  
Conduction Plane ◽  
Spectroscopy Studies ◽  
X Ray Absorption ◽  
Small Interactions

Synchrotron X-ray absorption near-edge structure (XANES) spectroscopy studies have been carried out on the electronic and crystal structure environments around the Al atom in Na+β-alumina and in two β-aluminas with Na+exchanged by Li+and Rb+. The aim is to define the type of interaction, if any, existing between the Al located in the `spinel block' and the fast-conducting cations in the `conduction plane'. Na+β′′-alumina has also been studied for comparison. All β-alumina spectra differ from that of α-alumina (corundum) by showing additional features due to the presence of tetrahedral Al. Moreover, they all show a much greater degree of local disorder. There are definite, but small, interactions between tetrahedral Al (and, possibly, also octahedral Al) in the `spinel block' and the Na+and Rb+cations in the `conduction plane'; Na+and Rb+β-aluminas have similar AlK-edge XANES features, but with intensities that change in relation to the weight of the `conduction plane' atom. Despite differences in composition and structure, Na+β′′-alumina shows the same behaviour, thus confirming the substantial similarity of the Al local environments. Li+-exchanged β-alumina has an AlK-edge XANES spectrum that apparently differs from all others, but actually conveys the same basic information. Indeed, interaction between Al and Li is much greater than in any other β-alumina because Li+moves laterally off the `conduction plane' to become close to a facing tetrahedral Al, and strongly interacts with it. Thus, this study also draws attention to the fact that β-aluminas react differently to alkali exchange.

scholarly journals Solving local structure around dopants in metal nanoparticles with ab initio modeling of X-ray absorption near edge structure

2016 ◽  
Vol 18 (29) ◽  
pp. 19621-19630 ◽  
Author(s):  
Janis Timoshenko ◽  
Atal Shivhare ◽  
Robert W. J. Scott ◽  
Deyu Lu ◽  
Anatoly I. Frenkel
Keyword(s):  
Ab Initio ◽  
Metal Nanoparticles ◽  
Local Structure ◽  
Heterogeneous Catalysts ◽  
Edge Structure ◽  
X Ray ◽  
Metal Impurities ◽  
Local Environments ◽  
X Ray Absorption ◽  
Xanes Analysis

XANES analysis guided by ab initio modeling is proposed for refinement of local environments around metal impurities in heterogeneous catalysts.

X-ray absorption near the edge structure and X-ray photoelectron spectroscopy studies on pyrite prepared by thermally sulfurizing iron films

2009 ◽  
Vol 18 (7) ◽  
pp. 2734-2738 ◽  
Author(s):  
Zhang Hui ◽  
Liu Ying-Shu ◽  
Wang Bao-Yi ◽  
Wei Long ◽  
Kui Re-Xi ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Iron Films ◽  
Edge Structure ◽  
X Ray ◽  
Spectroscopy Studies ◽  
X Ray Absorption

X-ray absorption spectroscopy studies for the determination of adsorption binding modes of selenium oxoanions onto iron and manganese based nanomaterials

2012 ◽  
Vol 1480 ◽  
Author(s):  
Christina M. Gonzalez ◽  
Jason G. Parsons ◽  
Jeffrey Hernandez ◽  
Jorge L. Gardea-Torresdey
Keyword(s):  
Absorption Spectroscopy ◽  
Binding Modes ◽  
Edge Structure ◽  
X Ray ◽  
Microwave Assisted ◽  
Spectroscopy Studies ◽  
X Ray Absorption ◽  
Binding Mechanisms ◽  
Iron And Manganese

ABSTRACTIncreasing concentrations of selenium oxoanions in the environment are placing many animals at risk for reproduction failure and deformities. The understanding of binding mechanisms of selenium oxoanions to iron and manganese based oxide minerals could lead to enhanced understanding of selenium mobility in the environment. In this study, the binding mechanisms of selenium oxoanions, selenite and selenate, to non microwave-assisted and microwave-assisted synthetic Fe3O4, Mn3O4, and MnFe2O4 nanomaterials were investigated through the use of X-ray absorption spectroscopy. The X-ray absorption near-edge structure (XANES) spectroscopy studies revealed the oxidation state of selenite and selenate remains the same after binding occurs to all nanomaterials in pH 2, 4, or 6 environments. The binding modes of selenite and selenate were determined to be bidentate binuclear through use of Extended x-ray absorption fine structure (EXAFS) and were independent of nanomaterials, synthetic technique, and pH.

Electronic Structure of P-Doped ZnO Films with p-Type Conductivity

2006 ◽  
Vol 6 (11) ◽  
pp. 3422-3425
Author(s):  
Veeramuthu Vaithianathan ◽  
Jong Ha Moon ◽  
Chang-Hwan Chang ◽  
Kandasami Asokan ◽  
Sang Sub Kim
Keyword(s):  
Electronic Structure ◽  
Xanes Spectrum ◽  
Sharp Decrease ◽  
Zno Films ◽  
Charge Neutrality ◽  
Edge Structure ◽  
X Ray ◽  
Doped Zno ◽  
P Type ◽  
X Ray Absorption

The electronic structure of laser-deposited P-doped ZnO films was investigated by X-ray absorption near-edge structure spectroscopy (XANES) at the O K-, Zn K-, and Zn L3-edges. While the O K-edge XANES spectrum of the n-type P-doped ZnO demonstrates that the density of unoccupied states, primarily O 2p–P 3sp hybridized states, is significantly high, the O K-edge XANES spectrum of the p-type P-doped ZnO shows a sharp decrease in intensity of the corresponding feature indicating that P replaces O sites in the ZnO lattice, and thereby generating PO. This produces holes to maintain charge neutrality that are responsible for the p-type behavior of P-doped ZnO. Both the Zn K-, and Zn L3-edge XANES spectra of the P-doped ZnO reveal that Zn plays no significant role in the p-type behavior of ZnO:P.

X-ray absorption near-edge structure (XANES) spectroscopy of fullerenes: inner-shell excitonic effects in fullerenes and the XANES spectrum of a higher fullerene C76

1994 ◽  
Vol 64 (2-3) ◽  
pp. 353-357 ◽  
Author(s):  
Kazuhiko Seki ◽  
Ryuichi Mitsumoto ◽  
Tohru Araki ◽  
Eisuke Ito ◽  
Yukio Ouchi ◽  
...  
Keyword(s):  
Xanes Spectrum ◽  
Xanes Spectroscopy ◽  
Edge Structure ◽  
X Ray ◽  
Excitonic Effects ◽  
X Ray Absorption

scholarly journals Tracking the Metal-Centered Triplet in Photoinduced Spin Crossover of Fe(phen)32+ with Tabletop Femtosecond M-edge XANES

2019 ◽  
Author(s):  
Kaili Zhang ◽  
Ryan Ash ◽  
Gregory S Girolami ◽  
Josh Vura-Weis
Keyword(s):  
Transient Absorption ◽  
Extreme Ultraviolet ◽  
Xanes Spectrum ◽  
Transient Absorption Spectroscopy ◽  
Fast Time ◽  
Edge Structure ◽  
X Ray ◽  
Ligand Charge Transfer ◽  
X Ray Absorption ◽  
Mlct State

<p>Fe(II) coordination complexes are promising alternatives to Ru(II) and Ir(III) chromophores for photoredox chemistry and solar energy conversion, but rapid deactivation of the initial metal-to-ligand charge transfer (MLCT) state to low-lying (d,d) states limits their performance. Relaxation to a <sup>5</sup>T<sub>2g</sub> state is postulated to occur via a metal-centered triplet state, but this mechanism remains controversial. We use femtosecond extreme ultraviolet (XUV) transient absorption spectroscopy to measure the excited-state relaxation of Fe(phen)<sub>3</sub><sup>2+</sup> and conclusively identify a <sup>3</sup>T intermediate that forms in 170 fs and decays to a vibrationally hot <sup>5</sup>T<sub>2g</sub> state in 40 fs. The shape of this M<sub>2,3</sub>-edge X-ray absorption near edge structure (XANES) spectrum is sensitive to the electronic structure of the metal center, and the high spin sensitivity, fast time resolution, and tabletop convenience of XUV transient absorption make it a powerful new tool for measuring the complex photophysics of transition metal complexes.</p>

scholarly journals Opportunities and challenges of applying advanced X-ray spectroscopy to actinide and lanthanide N-donor ligand systems

2022 ◽  
Vol 29 (1) ◽  
Author(s):  
Tim Pruessmann ◽  
Peter Nagel ◽  
Laura Simonelli ◽  
David Batchelor ◽  
Robert Gordon ◽  
...  
Keyword(s):  
Donor Ligands ◽  
Physical Processes ◽  
Edge Structure ◽  
Donor Ligand ◽  
X Ray ◽  
Trivalent Lanthanides ◽  
Novel Technique ◽  
Trivalent Actinides ◽  
Spectroscopy Studies ◽  
X Ray Absorption

N-donor ligands such as n-Pr-BTP [2,6-bis(5,6-dipropyl-1,2,4-triazin-3-yl)pyridine] preferentially bind trivalent actinides (An3+) over trivalent lanthanides (Ln3+) in liquid–liquid separation. However, the chemical and physical processes responsible for this selectivity are not yet well understood. Here, an explorative comparative X-ray spectroscopy and computational (L 3-edge) study for the An/Ln L 3-edge and the N K-edge of [An/Ln(n-Pr-BTP)3](NO3)3, [Ln(n-Pr-BTP)3](CF3SO3)3 and [Ln(n-Pr-BTP)3](ClO4)3 complexes is presented. High-resolution X-ray absorption near-edge structure (HR-XANES) L 3-edge data reveal additional features in the pre- and post-edge range of the spectra that are investigated using the quantum chemical codes FEFF and FDMNES. X-ray Raman spectroscopy studies demonstrate the applicability of this novel technique for investigations of liquid samples of partitioning systems at the N K-edge.

scholarly journals Tracking the Metal-Centered Triplet in Photoinduced Spin Crossover of Fe(phen)32+ with Tabletop Femtosecond M-edge XANES

2019 ◽  
Author(s):  
Kaili Zhang ◽  
Ryan Ash ◽  
Gregory S Girolami ◽  
Josh Vura-Weis
Keyword(s):  
Transient Absorption ◽  
Extreme Ultraviolet ◽  
Xanes Spectrum ◽  
Transient Absorption Spectroscopy ◽  
Fast Time ◽  
Edge Structure ◽  
X Ray ◽  
Ligand Charge Transfer ◽  
X Ray Absorption ◽  
Mlct State

<p>Fe(II) coordination complexes are promising alternatives to Ru(II) and Ir(III) chromophores for photoredox chemistry and solar energy conversion, but rapid deactivation of the initial metal-to-ligand charge transfer (MLCT) state to low-lying (d,d) states limits their performance. Relaxation to a <sup>5</sup>T<sub>2g</sub> state is postulated to occur via a metal-centered triplet state, but this mechanism remains controversial. We use femtosecond extreme ultraviolet (XUV) transient absorption spectroscopy to measure the excited-state relaxation of Fe(phen)<sub>3</sub><sup>2+</sup> and conclusively identify a <sup>3</sup>T intermediate that forms in 170 fs and decays to a vibrationally hot <sup>5</sup>T<sub>2g</sub> state in 40 fs. A coherent vibrational wavepacket with a period of 250 fs and damping time of 0.66 ps is observed on the <sup>5</sup>T<sub>2g</sub> surface, and the spectrum of this oscillation serves as a fingerprint for the Fe-N symmetric stretch. The results show that the shape of the M<sub>2,3</sub>-edge X-ray absorption near edge structure (XANES) spectrum is sensitive to the electronic structure of the metal center, and the high spin sensitivity, fast time resolution, and tabletop convenience of XUV transient absorption make it a powerful tool for studying the complex photophysics of transition metal complexes.<br></p>

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