scholarly journals Detailed Molecular and Structural Analysis of Dual Emitter IrQ(ppy)2 Complex

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1617
Author(s):  
Iulia Corina Ciobotaru ◽  
Daniel Nicolae Crisan ◽  
Primoz Šket ◽  
Constantin Claudiu Ciobotaru ◽  
Silviu Polosan
Keyword(s):  
Organometallic Compound ◽  
High Performance ◽  
Structural Model ◽  
Chemical Yield ◽  
Interatomic Distances ◽  
X Ray ◽  
Metal Ligands ◽  
Final Compound ◽  
X Ray Absorption ◽  
Detailed Molecular Analysis

The molecular structure of the 8-hydroxyquinoline–bis (2-phenylpyridyl) iridium (IrQ(ppy)2) dual emitter organometallic compound is determined based on detailed 1D and 2D nuclear magnetic resonance (NMR), to identify metal-ligands coordination, isomerization and chemical yield of the desired compound. Meanwhile, the extended X-ray absorption fine structure (EXAFS) was used to determine the interatomic distances around the iridium ion. From the NMR results, this compound IrQ(ppy)2 exhibits a trans isomerization with a distribution of coordinated N-atoms in a similar way to facial Ir(ppy)3. The EXAFS measurements confirm the structural model of the IrQ(ppy)2 compound where the oxygen atoms from the quinoline ligands induce the splitting of the next-nearest neighboring C in the second shell of the Ir3+ ions. The high-performance liquid chromatography (HPLC), as a part of the detailed molecular analysis, confirms the purity of the desired IrQ(ppy)2 organometallic compound as being more than 95%, together with the progress of the chemical reactions towards the final compound. The theoretical model of the IrQ(ppy)2, concerning the expected bond lengths, is compared with the structural model from the EXAFS and XRD measurements.

X-Ray Absorption Spectroscopic Studies of Catalytic Materials

1988 ◽  
Vol 143 ◽  
Author(s):  
G. H. Via ◽  
J. H. Sinfelt ◽  
G. Meitzner ◽  
F. W. Lytle
Keyword(s):  
Fine Structure ◽  
Physical Environment ◽  
Bimetallic Catalysts ◽  
Spectroscopic Studies ◽  
Interatomic Distances ◽  
X Ray ◽  
Coordination Numbers ◽  
Supported Platinum ◽  
High Fraction ◽  
X Ray Absorption

AbstractX-ray absorption spectra (XAS) contain information in the LIII near-edge region on filling of the absorber d-band, and in the extended fine-structure region on the physical environment of the absorber. We report here an evaluation of the effect on platinum LIII edges of preparation in clusters with a high fraction of Pt atoms at the surface. We also report the effects on platinum and rhenium LIII edges from addition of copper. These effects are surprisingly small.We have also re-evaluated extended x-ray absorption fine-structure spectra (EXAFS) of platinum and rhenium in alumina-supported platinum-rhenium bimetallic catalysts. A novel feature of this new analysis was the requirement that interatomic distances, coordination numbers, and Debye-Waller type factors maintain certain physically necessary relationships among themselves. This procedure decreased the number of free variables and increased the amount of information returned by the analysis.

scholarly journals Seleno-l-Methionine Is the Predominant Organic Form of Selenium in Cupriavidus metallidurans CH34 Exposed to Selenite or Selenate

2006 ◽  
Vol 72 (9) ◽  
pp. 6414-6416 ◽  
Author(s):  
Laure Avoscan ◽  
Richard Collins ◽  
Marie Carriere ◽  
Barbara Gouget ◽  
Jacques Cov�s
Keyword(s):  
Inductively Coupled Plasma ◽  
High Performance ◽  
Organic Form ◽  
Edge Structure ◽  
Cupriavidus Metallidurans Ch34 ◽  
X Ray ◽  
Inductively Coupled ◽  
Cupriavidus Metallidurans ◽  
Plasma Mass Spectrometry ◽  
X Ray Absorption

ABSTRACT The accumulated organic form of selenium previously detected by X-ray absorption near-edge structure (XANES) analyses in Cupriavidus metallidurans CH34 exposed to selenite or selenate was identified as seleno-l-methionine by coupling high-performance liquid chromatography to inductively coupled plasma-mass spectrometry.

Nanoscale determination of interatomic distance by ptychography-EXAFS method using advanced Kirkpatrick–Baez mirror focusing optics

2020 ◽  
Vol 27 (2) ◽  
pp. 455-461
Author(s):  
Makoto Hirose ◽  
Kei Shimomura ◽  
Takaya Higashino ◽  
Nozomu Ishiguro ◽  
Yukio Takahashi
Keyword(s):  
Wide Energy Range ◽  
X Rays ◽  
Bulk Materials ◽  
Interatomic Distances ◽  
X Ray ◽  
Combination Technique ◽  
Wide Energy ◽  
Diffraction Patterns ◽  
X Ray Absorption

This work demonstrates a combination technique of X-ray ptychography and the extended X-ray absorption fine structure (ptychography-EXAFS) method, which can determine the interatomic distances of bulk materials at the nanoscale. In the high-resolution ptychography-EXAFS method, it is necessary to use high-intense coherent X-rays with a uniform wavefront in a wide energy range, hence a ptychographic measurement system installed with advanced Kirkpatrick–Baez mirror focusing optics is developed and its performance is evaluated. Ptychographic diffraction patterns of micrometre-size MnO particles are collected by using this system at 139 energies between 6.504 keV and 7.114 keV including the Mn K absorption edge, and then the EXAFS of MnO is derived from the reconstructed images. By analyzing the EXAFS spectra obtained from a 48 nm × 48 nm region, the nanoscale bond lengths of the first and second coordination shells of MnO are determined. The present approach has great potential to elucidate the unclarified relationship among the morphology, electronic state and atomic arrangement of inhomogeneous bulk materials with high spatial resolution.

Synchrotron radiation in situ X-ray absorption fine structure and in situ X-ray diffraction analysis of a high-performance cobalt catalyst towards the oxygen reduction reaction

2017 ◽  
Vol 19 (45) ◽  
pp. 30749-30755
Author(s):  
Haiying Qin ◽  
Longxia Lin ◽  
Junkang Jia ◽  
Huangliang Ni ◽  
Yan He ◽  
...  
Keyword(s):  
Fine Structure ◽  
Synchrotron Radiation ◽  
Diffraction Analysis ◽  
High Performance ◽  
Cobalt Catalyst ◽  
Reduction Reaction ◽  
X Ray Diffraction ◽  
X Ray ◽  
X Ray Absorption

The evolution of metallic Co to Co(OH)2 and then to CoOOH during the ORR was revealed by in situ XRD combined with in situ XAFS tests.

Local structure around In atoms in coherently grownm-plane InGaN film

2017 ◽  
Vol 24 (5) ◽  
pp. 1012-1016
Author(s):  
Takafumi Miyanaga ◽  
Takashi Azuhata ◽  
Kiyofumi Nitta ◽  
Shigefusa F. Chichibu
Keyword(s):  
Quantum Wells ◽  
Local Structure ◽  
Interatomic Distance ◽  
Compressive Strain ◽  
Local Strain ◽  
Interatomic Distances ◽  
X Ray ◽  
Fitting Procedure ◽  
Excitonic Emission ◽  
X Ray Absorption

The local structure around In atoms in anm-plane In0.06Ga0.94N film coherently grown on a freestandingm-plane GaN substrate was investigated by polarization-dependent X-ray absorption fine-structure. A step-by-step fitting procedure was proposed for them-plane wurtzite structure. The interatomic distance for the first nearest neighbour In—N atomic pairs was almost isotropic. For the second nearest In—Ga pairs, the interatomic distances along them- anda-axes were longer and shorter, respectively, than that in strain-free virtual crystals as expected for them-plane compressive strain. In contrast, the In—Ga interatomic distance in thec-direction was elongated in spite of the compressive strain, which was explained in terms of the anisotropic atomic structure on them-plane. The local strain in them-plane film was more relaxed than that in coherently grownc-plane single quantum wells. A few In atoms were atomically localized in all directions, and thus localized excitonic emission is expected as in the case ofc-plane InGaN.

The nanoscale structure and unoccupied valence electronic states in FeSe1−xTex chalcogenides probed by X-ray absorption measurements

2015 ◽  
Vol 17 (27) ◽  
pp. 18131-18137 ◽  
Author(s):  
M. Y. Hacisalihoglu ◽  
E. Paris ◽  
B. Joseph ◽  
E. Yanmaz ◽  
N. L. Saini
Keyword(s):  
Electronic States ◽  
Interatomic Distances ◽  
X Ray ◽  
Nanoscale Structure ◽  
X Ray Absorption ◽  
Absorption Measurements

The Z-plot of random alloying in FeSe1−xTex characterized by coexisting interatomic distances at the nanoscale.

Fluorescence Yield Xanes and Exafs Experiments: Application to Highly Dilute and Surface Samples

1993 ◽  
Vol 37 ◽  
pp. 607-617 ◽  
Author(s):  
Glenn A. Waychunas ◽  
Gordon E. Brown
Keyword(s):  
Bound State ◽  
Fluorescence Yield ◽  
Interatomic Distances ◽  
Edge Structure ◽  
X Ray ◽  
Surface Samples ◽  
Radiation Sources ◽  
To Come ◽  
X Ray Absorption

The development of intense synchrotron radiation sources during the last twenty years has enabled several types of x-ray spectroscopy and scattering techniques to come into practical use. One of the most significant methods for the characterization of extremely dilute samples is high resolution x-ray absorption-edge spectroscopy. The technique is usually divided into two separate methods according to whether the x-ray absorption near edge structure (XANES) or the extended x-ray absorption fine structure (EXAFS) is analyzed. XANES features are due mainly to bound-state electronic transitions just below, and on the low energy side of the edge, and to multiple scattering resonances on the top of the edge and at somewhat higher energies. EXAFS features are oscillations due to ejected photoelectron back scattering interference processes in the close vicinity of the absorber atom. XANES analysis is used to determine atom valence, atom site distortion from regular geometries, and other details of the atom site. EXAFS features can be analyzed to recover interatomic distances between the absorber atom and its first few shells of neighbors, as well as the number and types of these neighbors. Together these techniques can provide an atomspecific probe of die short-range structure within almost any type of condensed matter.

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