Substitution effects in isomeric para and meta derivatives of benzonitrile revealed by UV photoelectron spectroscopy

1985 ◽  
Vol 50 (3) ◽  
pp. 650-657 ◽  
Author(s):  
Tomáš Juška
Keyword(s):  
Photoelectron Spectroscopy ◽  
Ionization Potentials ◽  
Photoelectron Spectra ◽  
Substitution Effects ◽  
Amino Group ◽  
Mndo Calculations ◽  
Derivatives Of ◽  
Uv Photoelectron Spectroscopy

The UV photoelectron spectra of isomeric para and meta derivatives of benzonitrile with substituents NO2, COCH3, Cl, Br, CH2I and NH2 were measured. Their assignment was carried out with the aid of MNDO calculations. The splitting of the highest π orbitals e1gS, e1gA is in all para derivatives greater than in their meta isomers, the greatest difference of splittings 0.25 eV being caused by the amino group. The level ordering e1gS, A exists in all molecules except meta NO2, and COCH3 derivatives where it is believed to be reverse. The π'CN - πCN splitting keeps nearly constant and it is close to that in benzonitrile. The ionization potentials of σ orbitals e1uS, e1uA, b2u and b1u in meta NO2 derivative are, in agreement with our expectation, higher than in benzonitrile. It is not true for para isomer where on the contrary, they are lower and they differ from meta isomer by 0.71-1.8 eV.

Tautomerism of pyrazoline-5-thione and triazoline-5-thione studied by variable temperature photoelectron spectroscopy

1983 ◽  
Vol 61 (6) ◽  
pp. 1197-1203 ◽  
Author(s):  
Claude Guimon ◽  
Geneviève Pfister-Guillouzo ◽  
Mlkael Begtrup
Keyword(s):  
Gaseous Phase ◽  
Photoelectron Spectroscopy ◽  
Variable Temperature ◽  
Thermal Isomerization ◽  
Photoelectron Spectra ◽  
Planar Form ◽  
Mndo Calculations

Photoelectron spectra at variable temperatures demonstrate that the rate of thermal isomerization of pyrazoline-5-thione (1a) into methylthiopyrazole(s) in the gaseous phase is metal catalysed. Similar isomerizations of triazolethione (2a and 3a) are at best only slightly so.Furthermore, photoelectron spectra and MNDO calculations show that gaseous methylthiopyrazoles (1b and 1c) and methylthiotriazoles (2b and 2c) exist predominantly in planar form for the b isomer and in nonplanar form for the c isomer. The ΔH0 for the rotameric equilibria is 2.7–4.2 kJ•mol−1.

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.

Study of Sulfur-Sulfur Nonbonded Interactions in Substituted Diphosphine Disulfides by Gas-Phase UV Photoelectron Spectroscopy

1981 ◽  
Vol 36 (1) ◽  
pp. 68-71
Author(s):  
Lucilla Alagna ◽  
Carla Cauletti ◽  
Marco Andreocci ◽  
Claudio Furlani ◽  
Gerhard Hagele
Keyword(s):  
Gas Phase ◽  
Photoelectron Spectroscopy ◽  
Photoelectron Spectra ◽  
Coupling Mechanism ◽  
Nonbonded Interactions ◽  
Lone Pairs ◽  
Uv Photoelectron Spectroscopy

Ultraviolet photoelectron spectra (UPS) of tetrasubstituted diphosphine disulfides RR'P(S)- P(S)RR' exhibit peculiar 1:2:1 splitting patterns in the region 7.5-9.5 eV for which a throughbond coupling mechanism between the sulfur lone pairs lying in the PPS planes is proposed. Further bond orbitals are related to bands at higher I. E. in the UP spectra

A Discussion on photoelectron spectroscopy - Photoelectron studies of boron compounds I. Diborane, borazine and B-trifluoroborazine

1970 ◽  
Vol 268 (1184) ◽  
pp. 97-109 ◽  
Keyword(s):  
Fine Structure ◽  
Photoelectron Spectroscopy ◽  
Molecular Orbitals ◽  
Ionization Potentials ◽  
Photoelectron Spectra ◽  
Energy Separation ◽  
Hydrogen Bridge ◽  
Boron Compounds ◽  
Vertical Ionization Potentials

The photoelectron spectra of diborane, hexadeuterodiborane, borazine and B -trifluoroborazine are presented, and adiabatic and vertical ionization potentials have been measured. The vibrational fine structure observed on some of the diborane bands is shown to be consistent with the forms of the molecular orbitals calculated by rigorous s.c.f. methods. The vertical i.p. of diborane are in better accord with a calculation which predicts a boron-boron bond in addition to the hydrogen bridge than with the calculations which indicate no direct boron-boron interaction. In borazine it is shown that the uppermost orbital is of π type rather than the σ type predicted by calculations, and that the extent of the π bonding, as measured by the energy separation of the π-type orbitals, is about 85 % of that in benzene. The effect of fluorination of borazine, as in benzene, is to stabilize the σ orbitals more than the π orbitals.

Analysis of X-ray Photoelectron Spectra through Their Even Derivatives

1979 ◽  
Vol 33 (5) ◽  
pp. 502-509 ◽  
Author(s):  
Attila E. Pavlath ◽  
Merle M. Millard
Keyword(s):  
Curve Fitting ◽  
Photoelectron Spectroscopy ◽  
Least Square ◽  
Photoelectron Spectra ◽  
Original Position ◽  
Noise Background ◽  
X Ray ◽  
Fitting Procedures ◽  
Higher Derivatives ◽  
Derivatives Of

The analysis of organic and inorganic surfaces can be carried out very effectively with the aid of x-ray photoelectron spectroscopy. In many cases, however, the presently available methods and techniques for data treatment resolutions are not suitable for the qualitative and quantitative identification of the various forms of a given atom on the same surface. The number of components and a good approximation of their original position in the composite curve must be known to use the available curve fitting procedures, otherwise the evaluation can be unreliable. It is suggested that the second and higher even derivatives of the composite could provide these data. The possibility of applying even derivatives of composite curves in combination with a nonlinear least square curve fitting program was investigated. It was found that depending on the noise background of the spectra, the resolution could be improved through this method. The resolution is dependent on the half-width of the component curves, their separation, and ratio. Both Gaussian and Lorentzian curves can be resolved, but the resolution of the latter is easier. The resolution is increasing with higher derivatives; however, increased smoothing must be applied at each step to neutralize the influence of the noise background.

The Hei and HeH Photoelectron Spectra of [Fe*?3-C3H5(CO)3X] and [Fe^3-C4H7 (CO)3X] (X = Cl, Br, I) and [CoC3H5(CO)3]

1982 ◽  
Vol 37 (2) ◽  
pp. 179-185 ◽  
Author(s):  
Jaap N. Louwen ◽  
Jaap Hart ◽  
Derk J. Stufkens ◽  
Ad Oskam
Keyword(s):  
Photoelectron Spectroscopy ◽  
Electronic Structures ◽  
Lone Pair ◽  
Iron Complexes ◽  
Photoelectron Spectra ◽  
Pair Type ◽  
Ionization Energies ◽  
Uv Photoelectron Spectroscopy

Abstract By means of UV photoelectron spectroscopy (UPS) the electronic structures of [Feη3.C3H5(CO)3X], [Feη3-(2-CH3C3H4)(CO)3X] (X = Cl, Br, I) and [Co(C3H5)(CO)3] have been studied. Detailed assignments are possible and surprisingly low ionization energies (as low as 8.19 eV) are found for iodine lone pair type Orbitals. From the spectra a large difference in π backbonding is found between the cobalt and iron complexes

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 Binding energy of solvated electrons and retrieval of true UV photoelectron spectra of liquids

2019 ◽  
Vol 5 (8) ◽  
pp. eaaw6896 ◽  
Author(s):  
Junichi Nishitani ◽  
Yo-ichi Yamamoto ◽  
Christopher W. West ◽  
Shutaro Karashima ◽  
Toshinori Suzuki
Keyword(s):  
Binding Energy ◽  
Photoelectron Spectroscopy ◽  
Extreme Ultraviolet ◽  
High Harmonic ◽  
Chemical Species ◽  
Electronic Energy ◽  
Photoelectron Spectra ◽  
Solvated Electrons ◽  
Energy Distributions ◽  
Uv Photoelectron Spectroscopy

The electronic energy and dynamics of solvated electrons, the simplest yet elusive chemical species, is of interest in chemistry, physics, and biology. Here, we present the electron binding energy distributions of solvated electrons in liquid water, methanol, and ethanol accurately measured using extreme ultraviolet (EUV) photoelectron spectroscopy of liquids with a single-order high harmonic. The distributions are Gaussian in all cases. Using the EUV and UV photoelectron spectra of solvated electrons, we succeeded in retrieving sharp electron kinetic energy distributions from the spectra broadened and energy shifted by inelastic scattering in liquids, overcoming an obstacle in ultrafast UV photoelectron spectroscopy of liquids. The method is demonstrated for the benchmark systems of charge transfer to solvent reaction and ultrafast internal conversion of hydrated electron from the first excited state.

Bicyclo[3.2.0]hepta-1,3,6-triene — UV photoelectron spectroscopic and computational studies

2005 ◽  
Vol 83 (9) ◽  
pp. 1352-1359 ◽  
Author(s):  
T Bajorek ◽  
N H Werstiuk
Keyword(s):  
Carbon Atom ◽  
Dft Calculations ◽  
Photoelectron Spectroscopy ◽  
Amine Oxide ◽  
Authentic Sample ◽  
Ionization Potentials ◽  
Spectral Subtraction ◽  
Computational Studies ◽  
Simulated Spectrum ◽  
Uv Photoelectron Spectroscopy

Pyrolysis of N,N-dimethylbicyclo[3.2.0]hepta-3,6-dien-1-amine oxide (5) at 120 °C in the source chamber of the UV photoelectron (PE) spectrometer yielded bicyclo[3.2.0]hepta-1,3,6-triene (6). The triene dimerizes to yield a mixture of two dimers in equal amounts. A PE spectrum of an authentic mixture of dimers was also recorded for the purpose of spectral subtraction. Pyrolysis of 5 also generates dimethylhydroxylamine (7), a spectrum of which was also recorded from an authentic sample. Spectral subtraction allowed the first two ionization potentials of triene 6 at 7.2 and 9.8 eV to be identified. The resultant PE spectrum was compared very favorably with a simulated spectrum obtained from DFT calculations. A QTAIM analysis and calculation of delocalization indexes showed that while homoconjugation between C4 and C6 is negligible there is a weak through-space interaction between the bridgehead carbon atom C1 and C6 of the four-membered ring.Key words: bicyclo[3.2.0]hepta-1,3,6-triene, UV photoelectron spectroscopy, DFT calculations, QTAIM, delocalization indexes.

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