The core binding energies of some gaseous aromatic carboxylic acids and their relationship to profon affinities and gas phase acidities

1988 ◽  
Vol 66 (8) ◽  
pp. 1919-1922 ◽  
Author(s):  
B. H. McQuaide ◽  
M. S. Banna
Keyword(s):  
Benzoic Acid ◽  
Gas Phase ◽  
Photoelectron Spectroscopy ◽  
Carbonyl Oxygen ◽  
Binding Energies ◽  
Proton Affinities ◽  
Initial State ◽  
X Ray ◽  
Inductive Effects ◽  
Oxygen Ionization

The C 1s and O 1s core binding energies of gaseous benzoic, phthalic, isophthalic, and terephthalic acids have been measured by X-ray photoelectron spectroscopy. The π-donor relaxation energies associated with the carbonyl oxygen ionization in these systems have been found to be around 2 eV, close to the value for acetic acid. Comparison of the O 1s binding energies in phenol and benzoic acid with the gas phase acidities shows that the increased acidity of benzoic acid is attributable mostly to initial-state inductive effects. A number of O 1s – proton affinity correlations have been used to predict proton affinities for these acids. It is found that benzoic acid is the strongest base and the weakest acid.

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]

N1s core binding energies for 2-, 3-, and 4-substituted pyridines determined by X-ray photoelectron spectroscopy. Correlations with theoretical models, substituent parameters, and gas phase basicities

1980 ◽  
Vol 58 (7) ◽  
pp. 694-703 ◽  
Author(s):  
R. S. Brown ◽  
A. Tse
Keyword(s):  
Gas Phase ◽  
Photoelectron Spectroscopy ◽  
Chemical Shifts ◽  
Theoretical Models ◽  
Binding Energies ◽  
X Ray ◽  
Theoretical Approaches ◽  
Substituted Pyridines ◽  
Monosubstituted Benzenes ◽  
Gas Phase Basicities

N1s binding energies for 36 pyridines substituted at the 2-, 3-, and 4-positions have been determined by X-ray photoelectron spectroscopy. The differences in BE relative to pyridine are analysed in terms of existing theoretical approaches (electrostatic, ground potential, and relaxation potential models) and compared with [Formula: see text] values calculated for analogous monosubstituted benzenes. One finds good correlations of [Formula: see text] with solution determined σ-substituent values although some substituent values deviate from the correlation probably due to solution effects which are not present in the gas phase. Correlations between [Formula: see text] and 14N nmr chemical shifts are poor, particularly for electron withdrawing substituents. The relationship between [Formula: see text] and gas phase basicity values (ΔG0) is good, and it appears as if the [Formula: see text] is more sensitive to the substituent than ΔG0. MINDO/3 calculations on the methoxypyridines and their conjugate acids employing full geometry optimizations are presented and analysed in order to determine the effect of geometric relaxation on the gas phase basicity.

Characterizing the Thermomechanical Degradation of a Filled Elastomer by Morphology and X Ray Photoelectron Spectroscopy

2001 ◽  
Vol 702 ◽  
Author(s):  
Giovanni F Crosta ◽  
Art J Nelson ◽  
Marina C Camatini
Keyword(s):  
Photoelectron Spectroscopy ◽  
Intrinsic Property ◽  
Binding Energies ◽  
Structural Domain ◽  
X Ray ◽  
Vulcanized Rubber ◽  
A Value ◽  
Debris Particles ◽  
Morphological Descriptor ◽  
Microscopy Images

ABSTRACTThree types of debris particles, denoted by L2, H2 and K3 respectively, originated from the abrasion of silica-filled, vulcanized rubber under different test conditions (severity) were analyzed and compared. The structural fractal dimension, DFS, of the particle perimeter was chosen as a morphological descriptor (but not necessarily as an intrinsic property of the fractured material !). Said dimension was estimated by processing light microscopy images. A value of the morphological threshold, TST, which separates the textural from the structural domain in the RICHARDSON plot was determined in order to maximize discrimination between the three particle types and rank them by increasing values of DFS. Particles from the highest severity test (K3) exhibited the highest value of DFS. X ray photoelectron spectroscopy (XPS) provided elemental composition, core level binding energies and the speciation of C, N, O, Si and S. As a result, L2 debris was found to originate from two processes: fracture of rubber and segregation of extender oil. Evidence has come both from morphology and XPS. Particles of H2 and K3 were ascribed to fracture alone. Comparison between K3 and the reference material, rasped rubber (RAS), shows the following: a) increase of the [S]/[C] surface atomic concentration ratio from RAS to K3; b) existence of multiple bonding states of S in K3 with energy peaking at 162.9 ± 0.3 eV ([-S-S-]n); c) weak contribution of R-S-O-R oxidized S species in K3 at 165 eV, not seen in RAS; d) no evidence of either SO3 or SO4 groups in any material. Although preliminary, these results prove the ability of morphological analysis and XPS to characterize the surface properties of debris particles non destructively.

Electronic structure modification in Fe substituted β-Ga2O3 from resonant photoemission and soft x-ray absotption spectroscopies

2021 ◽  
Author(s):  
Sahadeb Ghosh ◽  
Mangala Nand ◽  
Rajiv Kamparath ◽  
Mukul Gupta ◽  
Devdatta M Phase ◽  
...  
Keyword(s):  
Thin Films ◽  
Photoelectron Spectroscopy ◽  
Rf Magnetron Sputtering ◽  
Binding Energies ◽  
Transfer System ◽  
Structure Modification ◽  
X Ray ◽  
Resonant Photoemission ◽  
A Charge ◽  
Fe Substitution

Abstract Oriented thin films of β-(Ga1-xFex)2O3 have been deposited by RF magnetron sputtering on c-Al2O3 and GaN substrates. The itinerant character of Fe 3d states forming the top of the valence band (VB) of Fe substituted of β-Ga2O3 thin films has been determined from resonant photoelectron spectroscopy (RPES). Further, admixture of itinerant and localized character of these Fe 3d sates is obtained for larger binding energies i.e deeper of VB. The bottom of the conduction band (CB) for β-(Ga1-xFex)2O3 is also found to be strongly hybridized states involving Fe 3d and O 2p states as compared to that of Ga 4s in pristine β-Ga2O3. This suggests that β-Ga2O3 transforms from band like system to a charge transfer system with Fe substitution. Furthermore, the bandgap red shits with Fe composition, which has been found to be primarily related to the shift of the CB edge.

THE ADSORPTION GEOMETRY OF BENZOIC ACID ON Ni(110)

1999 ◽  
Vol 06 (01) ◽  
pp. 53-75 ◽  
Author(s):  
M. NEUBER ◽  
M. ZHARNIKOV ◽  
J. WALZ ◽  
M. GRUNZE
Keyword(s):  
Benzoic Acid ◽  
Photoelectron Spectroscopy ◽  
Thermal Desorption Spectroscopy ◽  
Adsorption Models ◽  
X Ray ◽  
Saturated Layer ◽  
Adsorbate Layer ◽  
Saturation Coverage ◽  
Adsorption Geometry ◽  
X Ray Absorption

The adsorption geometry of benzoic acid on Ni(110) was investigated by X-ray photoelectron spectroscopy, angle-resolved near edge X-ray absorption fine structure spectroscopy at the C1s and O1s excitation edges, and thermal desorption spectroscopy. At a substrate temperature of 360 K and saturation coverage the adsorbate forms a benzoate with molecules adsorbed on the surface via two equivalent oxygen atoms. For this dense adsorbate layer the molecular plane was found to be azimuthally rotated by about ± 30° with respect to the [Formula: see text] surface azimuth and tilted by ≈ 30° with respect to the surface normal. At about half the saturation coverage some rearrangement of molecules occurs in such a way that their planes become directed along the [001] surface direction, which is different from the adsorption geometry observed after annealing the saturated layer. At even smaller coverage the benzoate molecules appear to adsorb with their molecular planes nearly parallel to the surface. Semiempirical quantum-mechanical cluster calculations indicate that the carboxylate oxygens favor the highly coordinated sites in the [Formula: see text]-oriented troughs of the Ni(110) surface. Possible adsorption models are discussed.

Gas‐phase x‐ray photoelectron spectroscopy of model molecules relating to the thermochromism in poly(3‐alkylthiophene)

1990 ◽  
Vol 93 (9) ◽  
pp. 6357-6362 ◽  
Author(s):  
M. P. Keane ◽  
S. Svensson ◽  
A. Naves de Brito ◽  
N. Correia ◽  
S. Lunell ◽  
...  
Keyword(s):  
Gas Phase ◽  
Photoelectron Spectroscopy ◽  
X Ray

scholarly journals Electronic Spectroscopy of Isolated DNA Polyanions

2018 ◽  
Author(s):  
Steven Daly ◽  
Massimiliano Porrini ◽  
Frédéric Rosu ◽  
Valerie Gabelica
Keyword(s):  
Gas Phase ◽  
Absorption Spectra ◽  
Ion Mobility ◽  
Photoelectron Spectroscopy ◽  
Binding Energies ◽  
Action Spectroscopy ◽  
Action Spectra ◽  
Vis Spectroscopy ◽  
Electron Binding Energies ◽  
Electron Binding

In solution, UV-vis spectroscopy is often used to investigate structural changes in biomolecules (i.e., nucleic acids), owing to changes in the environment of their chromophores (i.e., the nucleobases). Here we address whether action spectroscopy could achieve the same for gas-phase ions, while taking the advantage of additional mass spectrometry and ion mobility separation of complex mixtures. We therefore systematically studied the action spectroscopy of homo-base 6-mer DNA strands (dG6, dA6, dC6, dT6), and discuss the results in light of gas-phase structures validated by ion mobility spectrometry and infrared ion spectroscopy, and in light of electron binding energies measured by photoelectron spectroscopy, and calculated electronic photo-absorption spectra. When UV photons interact with oligonucleotide polyanions, two main actions may take place: (1) fragmentation and (2) electron detachment. The action spectra reconstructed from fragmentation follow the absorption spectra well, and result from multiple cycles of absorption and internal conversion. The action spectra reconstructed from the electron photodetachment (EPD) efficiency reveal interesting phenomena: EPD depends on the charge state in a manner depending on electron binding energies, and is particularly efficient for purines but not pyrimidines. EPD thus reflects not only absorption, but also particular relaxation pathways of the electronic excited states. As these pathways lead to photo-oxidation, their investigation on model gas-phase systems may prove useful to elucidate mechanisms of photo-oxidative damages, which are linked to mutations and cancers.

scholarly journals Synthesis of new Ln4(Al2O6F2)O2 (Ln = Sm, Eu, Gd) phases with a cuspidine-related structure

IUCrJ ◽  
2019 ◽  
Vol 6 (1) ◽  
pp. 128-135 ◽  
Author(s):  
Aroa Morán-Ruiz ◽  
Aritza Wain-Martin ◽  
Alodia Orera ◽  
María Luisa Sanjuán ◽  
Aitor Larrañaga ◽  
...  
Keyword(s):  
Rare Earth ◽  
Low Temperature ◽  
Raman Spectra ◽  
Photoelectron Spectroscopy ◽  
Binding Energies ◽  
Temperature Reaction ◽  
Rietveld Refinements ◽  
X Ray ◽  
Vinylidene Difluoride ◽  
Vacant Position

The first fluorination of the cuspidine-related phases of Ln4(Al2O7□)O2 (where Ln = Sm, Eu, Gd) is reported. A low-temperature reaction with poly(vinylidene difluoride) lead to the fluorine being substituted in place of oxygen and inserted into the vacant position between the dialuminate groups. X-ray photoelectron spectroscopy shows the presence of the F 1s photoelectron together with an increase in Al 2p and rare-earth 4d binding energies supporting F incorporation. Energy-dispersive X-ray spectroscopy analyses are consistent with the formula Ln4(Al2O6F2)O2, confirming that substitution of one oxygen by two fluoride atoms has been achieved. Rietveld refinements show an expansion in the cell upon fluorination and confirm that the incorporation of fluoride in the Ln4(Al2O7□)O2 structure results in changes in Al coordination from four to five. Thus, the isolated tetrahedral dialuminate Al2O7 groups are converted to chains of distorted square-based pyramids. These structural results are also discussed based on Raman spectra.

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