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.

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]

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.

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.

scholarly journals XPS Investigations on Solid and Vacuum Deposited, Oxidized and Non-oxidized Palladium

1995 ◽  
Vol 50 (4-5) ◽  
pp. 381-387 ◽  
Author(s):  
Jürgen Kintrup ◽  
Harald Züchner
Keyword(s):  
Chemical Shift ◽  
Curve Fitting ◽  
Photoelectron Spectroscopy ◽  
Chemical Shifts ◽  
Atmospheric Oxygen ◽  
Hydrogen Permeability ◽  
Photoelectric Effect ◽  
High Accuracy ◽  
X Ray ◽  
Charging Effect

Abstract X-ray photoelectron spectroscopy (XPS) has been carried out to study the reaction of differently prepared palladium samples (solid and film Pd) with atmospheric oxygen. A careful curve fitting of the measured Pd-3d5/2 peak allows to separate the Pd-3d5/2 peak for Pd in surface PdO from the dominant Pd-3d5/2 peak of the non-oxidized bulk palladium and to determine the chemical shift of the "oxidized" Pa line with high accuracy. Differences in the chemical shifts for the surface PdO on solid and film palladium are explained by a different charging caused by the photoelectric effect in XPS measurements. The smaller charging effect observed for film palladium as compared to solid palladium indicates a stronger oxygen bonding to the (rougher) film palladium. The strong Pd-O bonding seems to be an essential reason for the reduced hydrogen-permeability of film palladium compared to solid palladium

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 Following excited-state chemical shifts in molecular ultrafast x-ray photoelectron spectroscopy

2022 ◽  
Vol 13 (1) ◽  
Author(s):  
D. Mayer ◽  
F. Lever ◽  
D. Picconi ◽  
J. Metje ◽  
S. Alisauskas ◽  
...  
Keyword(s):  
Excited State ◽  
Chemical Shift ◽  
Photoelectron Spectroscopy ◽  
Chemical Shifts ◽  
Excited Molecule ◽  
Charge Motion ◽  
Core Electron ◽  
Xps Spectra ◽  
X Ray ◽  
State Chemical

AbstractThe conversion of photon energy into other energetic forms in molecules is accompanied by charge moving on ultrafast timescales. We directly observe the charge motion at a specific site in an electronically excited molecule using time-resolved x-ray photoelectron spectroscopy (TR-XPS). We extend the concept of static chemical shift from conventional XPS by the excited-state chemical shift (ESCS), which is connected to the charge in the framework of a potential model. This allows us to invert TR-XPS spectra to the dynamic charge at a specific atom. We demonstrate the power of TR-XPS by using sulphur 2p-core-electron-emission probing to study the UV-excited dynamics of 2-thiouracil. The method allows us to discover that a major part of the population relaxes to the molecular ground state within 220–250 fs. In addition, a 250-fs oscillation, visible in the kinetic energy of the TR-XPS, reveals a coherent exchange of population among electronic states.

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