X-Ray Photoelectron Spectra of Aluminum Oxides: Structural Effects on the “Chemical Shift”

1973 ◽  
Vol 27 (1) ◽  
pp. 1-5 ◽  
Author(s):  
James R. Lindsay ◽  
Harry J. Rose ◽  
William E. Swartz ◽  
Plato H. Watts ◽  
Kenneth A. Rayburn
Keyword(s):  
Hydrogen Bonding ◽  
Binding Energy ◽  
Binding Energies ◽  
Photoelectron Spectra ◽  
Electrostatic Model ◽  
Structural Effects ◽  
Aluminum Oxides ◽  
X Ray ◽  
Structural Differences ◽  
Core Electrons

The aluminum (2p) electron spectra of several anhydrous and “hydrous” aluminum oxides have been recorded, and the binding energies have been measured. A simple electrostatic model is employed to explain the observed shift in binding energy and relate it to differences in structure and hydrogen bonding. Two conclusions can be drawn: structural differences must be considered when interpreting photoelectron spectra for inorganic crystalline substances; and hydrogen bonding with anions may have a measurable effect on the binding energy of core electrons of the cations.

scholarly journals X-ray photoelectron spectra structure and chemical bonding in AmO2

2015 ◽  
Vol 30 (2) ◽  
pp. 83-98 ◽  
Author(s):  
Yury Teterin ◽  
Konstantin Maslakov ◽  
Mikhail Ryzhkov ◽  
Anton Teterin ◽  
Kirill Ivanov ◽  
...  
Keyword(s):  
Binding Energy ◽  
Energy Range ◽  
Chemical Bond ◽  
Theoretical Data ◽  
Molecular Orbitals ◽  
Binding Energies ◽  
Photoelectron Spectra ◽  
Spectral Structure ◽  
Discrete Variation ◽  
X Ray

Quantitative analysis was done of the X-ray photoelectron spectra structure in the binding energy range of 0 eV to ~35 eV for americium dioxide (AmO2) valence electrons. The binding energies and structure of the core electronic shells (~35 eV-1250 eV), as well as the relativistic discrete variation calculation results for the Am63O216 and AmO8 (D4h) cluster reflecting Am close environment in AmO2 were taken into account. The experimental data show that the many-body effects and the multiplet splitting contribute to the spectral structure much less than the effects of formation of the outer (0-~15 eV binding energy) and the inner (~15 eV-~35 eV binding energy) valence molecular orbitals. The filled Am 5f electronic states were shown to form in the AmO2 valence band. The Am 6p electrons participate in formation of both the inner and the outer valence molecular orbitals (bands). The filled Am 6p3/2 and the O 2s electronic shells were found to make the largest contributions to the formation of the inner valence molecular orbitals. Contributions of electrons from different molecular orbitals to the chemical bond in the AmO8 cluster were evaluated. Composition and sequence order of molecular orbitals in the binding energy range 0-~35 eV in AmO2 were established. The experimental and theoretical data allowed a quantitative scheme of molecular orbitals for AmO2, which is fundamental for both understanding the chemical bond nature in americium dioxide and the interpretation of other X-ray spectra of AmO2.

X-ray photoelectron spectroscopic study of hydrated aluminas and aluminas

1994 ◽  
Vol 9 (11) ◽  
pp. 2919-2924 ◽  
Author(s):  
Takeshi Tsuchida ◽  
Hideaki Takahashi
Keyword(s):  
Binding Energy ◽  
Photoelectron Spectra ◽  
Molar Ratio ◽  
Oxygen Species ◽  
X Ray ◽  
Atomic Nuclei ◽  
Valence Electrons ◽  
Core Electrons ◽  
Equal Contribution

X-ray photoelectron spectra of hydrated aluminas (boehmite, diaspore, bayerite, and gibbsite), transition aluminas (y, δ, η, θ, X, and k –Al2O3) and corundum (α-Al2O3) have been studied for spectral characterization of each compound. The O1s spectra are shifted 0.2–1.2 eV to higher binding energy (Eb) in the order of α-Al2O3 < boehmite, diaspore < bayerite, gibbsite, and this agrees with the order of bulk OH/Al molar ratio in samples. The Eb and FWHM values of O1s spectra of transition aluminas depend on the ratio OH/O, i.e., the amount of OH− ions chemisorbed on them, and tend to decrease toward those of α-Al2O3 with increasing calcination temperature. Therefore, it is considered that an attracting effect of the proton on valence electrons in the hydroxyl oxygen causes the increased binding energy between core electrons and oxygen atomic nuclei. The broad O1s spectra of boehmite and diaspore can be deconvoluted into equal contribution from the two oxygen species in O2− and OH− ions in their structures.

A DFT study of spherands containing five anisyl groups — Highly preorganized to bind the alkali metal

2006 ◽  
Vol 84 (8) ◽  
pp. 1045-1049 ◽  
Author(s):  
Shabaan AK Elroby ◽  
Kyu Hwan Lee ◽  
Seung Joo Cho ◽  
Alan Hinchliffe
Keyword(s):  
Density Functional Theory ◽  
Binding Energy ◽  
Density Functional ◽  
Ionic Radius ◽  
Binding Energies ◽  
Cavity Size ◽  
X Ray Diffraction ◽  
Functional Theory ◽  
X Ray ◽  
Good Agreement

Although anisyl units are basically poor ligands for metal ions, the rigid placements of their oxygens during synthesis rather than during complexation are undoubtedly responsible for the enhanced binding and selectivity of the spherand. We used standard B3LYP/6-31G** (5d) density functional theory (DFT) to investigate the complexation between spherands containing five anisyl groups, with CH2–O–CH2 (2) and CH2–S–CH2 (3) units in an 18-membered macrocyclic ring, and the cationic guests (Li+, Na+, and K+). Our geometric structure results for spherands 1, 2, and 3 are in good agreement with the previously reported X-ray diffraction data. The absolute values of the binding energy of all the spherands are inversely proportional to the ionic radius of the guests. The results, taken as a whole, show that replacement of one anisyl group by CH2–O–CH2 (2) and CH2–S–CH2 (3) makes the cavity bigger and less preorganized. In addition, both the binding and specificity decrease for small ions. The spherands 2 and 3 appear beautifully preorganized to bind all guests, so it is not surprising that their binding energies are close to the parent spherand 1. Interestingly, there is a clear linear relation between the radius of the cavity and the binding energy (R2 = 0.999).Key words: spherands, preorganization, density functional theory, binding energy, cavity size.

O 1s Core-Level Positions of Bi2Sr2CaCu2O8-x by OKα-Ray Emission

1989 ◽  
Vol 44 (9) ◽  
pp. 780-784
Author(s):  
F. Burgäzy ◽  
C. Politis ◽  
P. Lamparter ◽  
S. Steeb
Keyword(s):  
Binding Energy ◽  
Energy Level ◽  
Photoelectron Spectrum ◽  
Local Density ◽  
Binding Energies ◽  
Core Level ◽  
X Ray ◽  
Band Structure Calculations ◽  
Density Band ◽  
Structure Calculations

Abstract The measured O Kα X-ray emission spectrum of the high-Tc superconductor Bi2Sr2CaCu2O8-x is compared with a spectrum based on local density band structure calculations. By taking also into account the shape of the measured O 1s X-ray photoelectron spectrum an energy level diagram for the O 1s core-level binding energies of the three different oxygen sites is constructed. The O 1s binding energy in the Bi2O2-layers is found to be about the same as that one in the SrO-layers, whereas the binding energy in the CuO2-layers is lower by about 0.5 eV.

X-Ray photoelectron spectroscopy of monosubstituted perfluorobenzenes

1977 ◽  
Vol 55 (8) ◽  
pp. 1279-1284 ◽  
Author(s):  
Barry C. Trudell ◽  
S. James W. Price
Keyword(s):  
Gas Phase ◽  
Photoelectron Spectroscopy ◽  
Binding Energies ◽  
Photoelectron Spectra ◽  
Atomic Charges ◽  
X Ray ◽  
Sophisticated Analysis ◽  
Charge Calculations

The gas phase X-ray photoelectron spectra, XPS, were observed for the series C6F5X (X = F, Cl, I, Br, H). Binding energies were determined from the spectra using the ESCAPLOT Program. Charge calculations were carried out using Equalization of Electronegativity, CNDO/2, and ACHARGE approaches on each molecule. The more sophisticated analysis leads to the following equation correlating the (C 1s) binding energies and the atomic charges qi[Formula: see text]

Probing Intramolecular Interaction of Stereoisomers Using Computational Spectroscopy

2020 ◽  
Vol 73 (8) ◽  
pp. 813
Author(s):  
Feng Wang ◽  
Shawkat Islam ◽  
Frederick Backler
Keyword(s):  
Hydrogen Bonding ◽  
Binding Energy ◽  
Gas Phase ◽  
Intramolecular Interaction ◽  
Dipole Moments ◽  
Energy Difference ◽  
Binding Energies ◽  
Intramolecular Interactions ◽  
Computational Spectroscopy ◽  
Ionic States

Several model stereoisomers such as ferrocene (Fc), methoxyphenol, and furfural conformers are discussed. It was discovered that the Fc IR spectroscopic band(s) below 500cm−1 serve as fingerprints for eclipsed (splitting 17 (471–488)cm−1) and staggered Fc (splitting is ~2 (459–461)cm−1) in the gas phase. It is revealed that in the gas phase the dominance of the eclipsed Fc (D5h) at very low temperatures changes to a mixture of both eclipsed and staggered Fc when the temperature increases. However, in solvents such as CCl4, eclipsed Fc dominates at room temperature (300K) due to the additional solvation energy. Intramolecular interactions of organic model compounds such as methoxyphenols (guaiacol (GUA) and mequinol (MEQ)) and furfural, ionization energies such as the carbon 1s (core C1s), as well as valence binding energy spectra serve this purpose well. Hydrogen bonding alters the C1s binding energies of the methoxy carbon (C(7)) of anti-syn and anti-gauche conformers of GUA to 292.65 and 291.91eV, respectively. The trans and cis MEQ conformers, on the other hand, are nearly energy degenerate, whereas their dipole moments are significantly different: 2.66 Debye for cis and 0.63 Debye for trans-MEQ. Moreover, it is found that rotation around the Cring–OH and the Cring–OCH3 bonds differ in energy barrier height by ~0.50 kcal⋅mol−1. The Dyson orbital momentum profiles of the most different ionic states, 25a′ (0.35eV) and 3a′ (−0.33eV), between cis and trans-MEQ in outer valence space (which is measurable using electron momentum spectroscopy (EMS)), exhibit quantitative differences. Finally, the molecular switch from trans and cis-furfural engages with a small energy difference of 0.74 kcal mol−1, however, at the calculated C(3)(–H⋅⋅⋅O=C) site the C1s binding energy difference is 0.105eV (2.42 kcal mol−1) and the NMR chemical shift of the same carbon site is also significant; 7.58ppm from cis-furfural without hydrogen bonding.

Structure and Conformations of Gaba-Transaminase Inhibitors. I. Multisubstrate Analogs

1986 ◽  
Vol 39 (10) ◽  
pp. 1559
Author(s):  
PR Andrews ◽  
V Cody ◽  
MN Iskander ◽  
AI Jeffrey ◽  
MF Mackay ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Transition State ◽  
Intramolecular Hydrogen Bonding ◽  
Side Chain ◽  
Gaba Transaminase ◽  
X Ray ◽  
Potential Energy Calculations ◽  
Phenolic Oxygen ◽  
Structural Differences ◽  
Intramolecular Hydrogen

Two multisubstrate analogues of the transition state in the reaction catalysed by the enzyme GABA- transaminase (E.C. 2.6.1.19), sulfonic acid pyridoxal dervative , C10H16N2O5S (1) and carboxylic acid pyridoxal derivative, C13H18N2O4 (2), have been characterized by X-ray analyses of crystals of (1). HCl , (1).H2O and (2). HCl . In each structure, the nitrogen on the side chain is the donor in intramolecular hydrogen bonding. However, it is only in (2). HCl that this interaction is with the phenolic oxygen as postulated in the proposed transition state of the reaction catalysed by GABA- transaminase . For both structures of (1), on the other hand, this interaction is with the oxygen of the ring hydroxymethyl substituent, and results in a seven- membered ring. Conformational analysis indicates that both modes of hydrogen bonding may be present in the pyridoxal derivatives, although no quantitative assessment is possible at the MINDO/3 or MNDO levels. Simple classical potential energy calculations indicate significant structural differences between the lowest energy conformations of these compounds and the calculated transition state. However, conformations which match the key features of the transition state are also relatively low in energy.

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