Photoelectron Spectra of Phosgene and Thiophosgene

1972 ◽  
Vol 50 (5) ◽  
pp. 737-746 ◽  
Author(s):  
David Chadwick
Keyword(s):  
High Resolution ◽  
Molecular Orbital ◽  
Strong Interaction ◽  
Lone Pair ◽  
Ionization Potentials ◽  
Photoelectron Spectra ◽  
Lone Pair Electrons

The high resolution photoelectron spectra of phosgene and thiophosgene have been obtained and, in each case, all ionization potentials up to 21.2 eV determined. The spectra are interpreted in terms of the molecular orbital structures and it is concluded that there is a strong interaction between the chlorine pπ "lone pair" electrons and those in the C=O or C=S π bond. The measured ionization potentials are compared with those calculated by the CNDO/2 method and with those obtained for similar molecules.

VUV FRAGMENTATION OF SOME HYDROFLUOROCARBON CATIONS STUDIED USING COINCIDENCE TECHNIQUES

2002 ◽  
Vol 09 (01) ◽  
pp. 153-158 ◽  
Author(s):  
WEIDONG ZHOU ◽  
D. P. SECCOMBE ◽  
R. Y. L. CHIM ◽  
R. P. TUCKETT
Keyword(s):  
Kinetic Energy ◽  
Ab Initio ◽  
Ground State ◽  
Lower Energy ◽  
Lone Pair ◽  
Electronic States ◽  
Photoelectron Spectra ◽  
Highest Occupied Molecular Orbital ◽  
Impulsive Model ◽  
Lone Pair Electrons

Threshold photoelectron–photoion coincidence (TPEPICO) spectroscopy has been used to investigate the decay dynamics of the valence electronic states of the parent cation of several hydrofluorocarbons (HFC), based on fluorine-substituted ethane, in the energy range 11–25 eV. We present data for CF 3– CHF 2, CF 3– CH 2 F , CF 3– CH 3 and CHF 2– CH 3. The threshold photoelectron spectra (TPES) of these molecules show a common feature of a broad, relatively weak ground state, associated with electron removal from the highest-occupied molecular orbital (HOMO) having mainly C–C σ-bonding character. Adiabatic and vertical ionisation energies for the HOMO of the four HFCs are presented, together with corresponding values from ab initio calculations. For those lower-energy molecular orbitals associated with non-bonding fluorine 2pπ lone pair electrons, these electronic states of the HFC cation decay impulsively by C–F bond fission with considerable release of translational kinetic energy. Appearance energies are presented for formation of the daughter cation formed by such a process (e.g. CF 3– CHF +), together with ab initio energies of the corresponding dissociation channel (e.g. CF 3– CHF + + F ). Values for the translational kinetic energy released are compared with the predictions of a pure-impulsive model.

A Discussion on photoelectron spectroscopy - Orderings of π and σ ionization potentials in carbocyclic and heterocyclic aromatic compounds

1970 ◽  
Vol 268 (1184) ◽  
pp. 131-140 ◽  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Aromatic Compounds ◽  
Lone Pair ◽  
Ionization Potentials ◽  
Photoelectron Spectra ◽  
Light Sources ◽  
Orbital Energies ◽  
Substituted Pyridines ◽  
Nitrogen Lone Pair ◽  
Electron Correlation Effects

Data on calculated orbital energies and experimentally measured ionization potentials of carbocyclic and heterocyclic aromatic compounds are compared and contrasted. The ordering or orbital energies and ionization potentials do not always seem to parallel one another, probably owing to either electron correlation effects, or to deviations from Koopman’s theorem. The effects on photoelectron spectra of using different light sources and analysers are discussed in relation to their bearing on the orbital orderings of aromatic compounds. The high resolution He 584 A. photoelectron spectrum of pyridine is shown to be open to two interpretations regarding the ordering of the ionization potentials of the π orbitals and the ‘nitrogen lone pair’ (n). One of the interpretations involves the three lowest pyridine ionization potentials being π (9.2 eV), π L (9.5 eV) and n (10.5 eV) whilst the other has the first three ionization potentials being the order π , n, π . The photoelectron spectra of substituted pyridines and diazines are discussed in the light of the two possible explanations for the pyridine spectrum.

Photoelectron Spectrum and Electronic Structure of Tetrathiofulvalene (TTF)

1974 ◽  
Vol 52 (19) ◽  
pp. 3373-3377 ◽  
Author(s):  
A. John Berlinsky ◽  
James F. Carolan ◽  
Larry Weiler
Keyword(s):  
Electronic Structure ◽  
Band Structure ◽  
Molecular Orbital ◽  
Photoelectron Spectrum ◽  
Crystal Packing ◽  
Ionization Potentials ◽  
Photoelectron Spectra ◽  
Molecular Orbital Calculations ◽  
Conducting Salt

The electronic structure of tetrathiofulvalene (TTF) has been determined from its photoelectron spectrum and the photoelectron data for the tetrahydro derivative of TTF and 1,3-dithiolane. Correlations of the ionization potentials (i.p.) and several molecular orbital calculations are used in the assignment of the photoelectron spectra of these three compounds. The first five i.p. of TTF and their assignment are as follows: 6.92 (3b1u), 8.67 (2b2g), 9.73 (2b1u), 10.16 (au) and 10.49 eV (b3g). The sixth i.p. at 11.00 eV is tentatively assigned to the 1b2g level. The electronic structure of TTF is important in understanding the crystal packing and band structure of the highly conducting salt, TTF•TCNQ.

Molecular association in liquids I. Molecular association due to lone-pair electrons

1951 ◽  
Vol 205 (1081) ◽  
pp. 155-162 ◽  
Keyword(s):  
Molecular Orbital ◽  
Liquid State ◽  
Lone Pair ◽  
Molecular Association ◽  
Molecular Orbital Theory ◽  
Orbital Theory ◽  
General Survey ◽  
Quantitative Theory ◽  
Lone Pair Electrons ◽  
The Way

This paper aims at giving a general survey of the part played by lone-pair electrons in the range of phenomena commonly classified under the heading of molecular association, with particular emphasis on the liquid state. The position of lone-pair electrons on a molecule and the factors determining their availability for forming intermolecular links are discussed in terms of molecular orbital theory. This is followed by an examination of the way in which these association forces influence the structure of large aggregates of molecules as in liquids. The lines along which a quantitative theory of associated liquids may be developed are indicated.

High resolution molecular photoelectron spectroscopy. III. Acetylenes and aza-acetylenes

1968 ◽  
Vol 308 (1492) ◽  
pp. 19-37 ◽  
Keyword(s):  
Fine Structure ◽  
High Resolution ◽  
Photoelectron Spectroscopy ◽  
Hydrogen Cyanide ◽  
Ionization Potentials ◽  
Photoelectron Spectra

The 584 Å (21·22 eV) photoelectron, spectra of the following linear unsaturated molecules are reported: acetylene, dideutero-acetylene, hydrogen cyanide, deuterium cyanide, diacetylene, dideutero-diacetylene, cyanoacetylene, cyanogen, dicyanoacetylene, methylacetylene and dimethyltriacetylene. The ionization potentials of the molecules, and the vibrational fine structure observed in many of the bands, are discussed.

scholarly journals Ionization potentials of nitriles — Photoelectron spectra of succinonitrile and glutaronitrile

2006 ◽  
Vol 84 (9) ◽  
pp. 1124-1131 ◽  
Author(s):  
Heidi M Muchall ◽  
Nick H Werstiuk
Keyword(s):  
Energy Region ◽  
Photoelectron Spectrum ◽  
Lone Pair ◽  
Low Energy ◽  
Ionization Potentials ◽  
Photoelectron Spectra ◽  
Proton Affinities ◽  
Nitrogen Lone Pair ◽  
D Model ◽  
Highest Occupied Molecular Orbitals

The He(I) photoelectron spectra of succinonitrile (1) and glutaronitrile (2), both with extensive overlap of ionization bands in the low-energy region, are reported. To assign ionizations, we studied the conformational behaviour and resulting ionization energy dependence of 1 and 2 computationally with the B3LYP/6-31+G(d) model chemistry based on the fact that it reliably reproduces the ionization potentials of eleven mono- and di-nitriles, both saturated and unsaturated. The correlation of proton affinities with observed ionization potentials of 1, 2, and malononitrile establishes the orbital sequence of four C≡N π orbitals followed by two nitrogen lone pair orbitals as the highest occupied molecular orbitals for all three compounds.Key words: photoelectron spectrum, ionization potential, conformational dependence, nitrile, DFT.

scholarly journals Highly-Excited State Properties of Cumulenone Chlorides in the Vacuum-Ultraviolet

2020 ◽  
Author(s):  
Quynh Nguyen ◽  
William Peters ◽  
Ryan Fortenberry
Keyword(s):  
Excited States ◽  
Vacuum Ultraviolet ◽  
Lone Pair ◽  
Carbon Chain ◽  
Ionization Potentials ◽  
Photoelectron Spectra ◽  
Chain Elongation ◽  
Electronic Excitations ◽  
Quantum Chemical Analysis ◽  
Poten Tials

<div><div><div><p>Recent observations of chloromethane in interstellar environments suggest that other organohalo- gens, which are known to be critically important in Earth′s atmosphere, may also be of significance beyond our own terrestrial veil. This raises the question of how such molecules behave under extreme conditions such as when exposed to vacuum ultraviolet (VUV) radiation. VUV photons promote molecules to highly excited states that fragment in non-statistical patterns controlled by the initial femtosecond dynamics. A detailed understanding of VUV-driven photochemistry in complex organic molecules that consist of more than one functional group is a particularly challenging task. This quantum chemical analysis reports the electronic states and ionization potentials up to the VUV range (6 - 11 eV) of the chlorine-substituted cumulenone series molecules. The valence and Rydberg properties of lone-pair terminated, π-conjugated systems are explored for their potential resonance with lone pairs from elsewhere in the system. The carbon chain elongation within the family ClHCnO, where n=1-4, influences the electronic excitations, associated wavefunctions, and ionization poten- tials of the molecules. The predicted geometries and ionization potentials are in good agreement with the available experimental photoelectron spectra for formyl chloride and chloroketene, n=1-2. Furthermore, comparison between the regular cumulenone species and the corresponding chlorinated derivatives exhibit similar behaviors especially for n=3, where the allene backbone in propadienone chloride is severely bent. Most notably for the excited states is that the Rydberg character becomes more dominant as the energy increases, with some retaining valence characters.</p></div></div></div>

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