scholarly journals Experimental and theoretical 2p core-level spectra of size-selected gas-phase aluminum and silicon cluster cations: chemical shifts, geometric structure, and coordination-dependent screening

2019 ◽  
Vol 21 (12) ◽  
pp. 6651-6661 ◽  
Author(s):  
Michael Walter ◽  
Marlene Vogel ◽  
Vicente Zamudio-Bayer ◽  
Rebecka Lindblad ◽  
Thomas Reichenbach ◽  
...  
Keyword(s):  
Gas Phase ◽  
Geometric Structure ◽  
Ground State ◽  
Chemical Shifts ◽  
Binding Energies ◽  
Core Level ◽  
Silicon Cluster ◽  
Size Selected Clusters

2p binding energies of size-selected clusters reveal bonding motifs and help to assign new ground state geometries.

An ESCA Investigation of some Halogeno(methyl)-Silane and -Germane Series

1975 ◽  
Vol 53 (23) ◽  
pp. 3602-3612 ◽  
Author(s):  
John E. Drake ◽  
Chris Riddle ◽  
L. Coatsworth
Keyword(s):  
Binding Energy ◽  
Chemical Shifts ◽  
Binding Energies ◽  
Core Level ◽  
Atomic Charges ◽  
Electronegativity Equalization

Core-level binding energies of all atoms are reported for two series of compounds; MenMCl4−n and Me3MX (n = 0 → 4, M = Si or Ge, X = F, Cl, Br, I and (for M = Ge) CN, N3, and NCS ). Binding energy shifts are discussed using a 'whole-molecule' approach and are correlated with estimated atomic charges derived from an electronegativity-equalization procedure. Carbon 1s binding energies are also correlated to 13C n.m.r. chemical shifts.

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.

scholarly journals H-bonds and Protons in Molecular Crystals: Insight from Combined XPS/ssNMR/XRD

2014 ◽  
Vol 70 (a1) ◽  
pp. C531-C531
Author(s):  
Joanna Stevens ◽  
Stephen Byard ◽  
Colin Seaton ◽  
Ghazala Sadiq ◽  
Roger Davey ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Proton Transfer ◽  
Chemical Shifts ◽  
Molecular Crystals ◽  
Binding Energies ◽  
Core Level ◽  
Chemical Environment ◽  
Crystallographic Structure ◽  
Structure Information ◽  
Wide Range

Physicochemical properties of molecular crystals are significantly influenced by non-covalent interactions and proton transfer. A well known application is the tuning of solubility, bioavailability and stability of pharmaceutical actives through co-crystal (hydrogen-bonding) or salt (ionic, Brønsted acceptors) formation. X-ray Photoelectron Spectroscopy (XPS) is an intrinsically local structural probe, providing information on the chemical state and chemical environment of atoms in molecules and crystals through the photoemission of core level electrons. We have recently studied a wide range of acid-base complexes in molecular crystals and found that analyzing the chemical shifts of N1s core level binding energies provides a facile route for characterizing the chemical and structural changes at functional groups involved in hydrogen bonding and proton transfer [1]. Very importantly, XPS unequivocally distinguishes protonated (salt) from hydrogen-bonded (co-crystal) nitrogen moieties. We have complemented our results for nitrogen species with 15N Solid-State Nuclear Magnetic Resonance (ssNMR) chemical shifts, which reveal low frequency shifts with protonation, but the magnitude of these shifts is additionally influenced by the wider chemical environment [2]. When crystallographic structure information is available, ssNMR shifts can be computationally predicted and thereby related to H-bond lengths, giving a measure of H-bond strength (NMR crystallography). The wide variety of donor/acceptor systems we have investigated has covered a large range of pKa values and demonstrates the generic nature of taking an XPS/ssNMR/XRD approach to organic molecule crystallography (Fig 1). The excellent agreement between the conclusions drawn by XPS and combined ssNMR/CASTEP investigations opens up a reliable avenue for local structure characterization in molecular systems even in the absence of crystal structure information, for example with non-crystalline or amorphous matter.

Chemical shifts of the core-level binding energies for the alkaline-earth oxides

1992 ◽  
Vol 196 (6) ◽  
pp. 641-646 ◽  
Author(s):  
Paul S. Bagus ◽  
G. Pacchioni ◽  
C. Sousa ◽  
T. Minerva ◽  
F. Parmigiani
Keyword(s):  
Alkaline Earth ◽  
Chemical Shifts ◽  
Binding Energies ◽  
Core Level ◽  
The Core

scholarly journals Negative ion photoelectron spectroscopy confirms the prediction that D3h carbon trioxide (CO3) has a singlet ground state

2016 ◽  
Vol 7 (2) ◽  
pp. 1142-1150 ◽  
Author(s):  
David A. Hrovat ◽  
Gao-Lei Hou ◽  
Bo Chen ◽  
Xue-Bin Wang ◽  
Weston Thatcher Borden
Keyword(s):  
Gas Phase ◽  
Ground State ◽  
Photoelectron Spectroscopy ◽  
Radical Anion ◽  
Negative Ion ◽  
Singlet Ground State

The CO3 radical anion (CO3˙−) has been formed by electrospraying carbonate dianion (CO32−) into the gas phase.

The Dielectric Discharge as an Efficient Generator of Active Nitrogen for Chemiluminescence and Analysis

1983 ◽  
Vol 37 (6) ◽  
pp. 545-552 ◽  
Author(s):  
John Kishman ◽  
Eric Barish ◽  
Ralph Allen
Keyword(s):  
Gas Phase ◽  
Ground State ◽  
Band System ◽  
Electrothermal Atomization ◽  
Characteristic Radiation ◽  
Gaseous Species ◽  
Vibrationally Excited ◽  
Active Nitrogen ◽  
Excited Species ◽  
Intense Emission

A predominantly blue “active nitrogen” afterglow was generated in pure flowing nitrogen or in air by using a dielectric discharge at pressures from 1 to 20 Torr. The afterglow contains triplet state molecules and vibrationally excited ground state molecules. These species are produced directly by electron impact without the formation and recombination of nitrogen atoms. The most intense emission is the N2 second positive band system. The N2 first positive and N2+ first negative systems are also observed. The spectral and electrical properties of this discharge are discussed in order to establish guidelines for the analytical use of the afterglow for chemiluminescence reactions. The metastatic nitrogen efficiently transfers its energy to atomic and molecular species which are introduced into the gas phase and these excited species emit characteristic radiation. The effects of electrothermal atomization of Zn and the introduction of gaseous species (e.g., NO) on the afterglow are described.

scholarly journals Chemical shifts in boron 1s binding energies of some gaseous compounds

1972 ◽  
Vol 94 (5) ◽  
pp. 1540-1542 ◽  
Author(s):  
Patricia Finn ◽  
William L. Jolly
Keyword(s):  
Chemical Shifts ◽  
Binding Energies
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