Difluoroborane, HBF2. A study by HeI photoelectron spectroscopy, and ab initio methods including perturbation corrections to Koopmans' theorem

Abstract The He (I) photoelectron spectrum of gaseous S4N2 is reported, and an assignment is made on the basis of the correlation with ab initio molecular orbital calculations. The latter, based upon the recently optimised geometry of Cѕ symmetry, used both a large basis set of greater than double zeta quality, together with configuration for both the ground state and the ionised states. The Koopmans’ Theorem order gives a reasonable prediction of the order of states for most of the low energy ionised states; beyond IP5 additional states involving excitation processes in conjunction with ionisation were computed. The numerical agreement between the observed IP’s and the CI value is reasonable.

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Spatially Resolved Photoelectron Spectroscopy: Recent Progress and Future Plans

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010013554x ◽

1990 ◽

Vol 48 (2) ◽

pp. 388-389

Author(s):

A. M. Bradshaw

Keyword(s):

Photoelectron Spectroscopy ◽

Chemical Reactivity ◽

Target Material ◽

Orbital Energy ◽

Light Sources ◽

Analytical Technique ◽

Hartree Fock ◽

Spatially Resolved ◽

Koopmans Theorem ◽

Surface Analytical Technique

X-ray photoelectron spectroscopy (XPS or ESCA) was not developed by Siegbahn and co-workers as a surface analytical technique, but rather as a general probe of electronic structure and chemical reactivity. The method is based on the phenomenon of photoionisation: The absorption of monochromatic radiation in the target material (free atoms, molecules, solids or liquids) causes electrons to be injected into the vacuum continuum. Pseudo-monochromatic laboratory light sources (e.g. AlKα) have mostly been used hitherto for this excitation; in recent years synchrotron radiation has become increasingly important. A kinetic energy analysis of the so-called photoelectrons gives rise to a spectrum which consists of a series of lines corresponding to each discrete core and valence level of the system. The measured binding energy, EB, given by EB = hv−EK, where EK is the kineticenergy relative to the vacuum level, may be equated with the orbital energy derived from a Hartree-Fock SCF calculation of the system under consideration (Koopmans theorem).

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RELATIVISTIC EFFECTS IN THE CALCULATION OF OSCILLATOR STRENGTHS : "AB INITIO" METHODS

Le Journal de Physique Colloques ◽

10.1051/jphyscol:1979120 ◽

1979 ◽

Vol 40 (C1) ◽

pp. C1-109-C1-114

Author(s):

J. P. Desclaux

Keyword(s):

Ab Initio ◽

Relativistic Effects ◽

Oscillator Strengths ◽

Ab Initio Methods

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Determination of acidic dissociation constants of L-phenylalanyl-glycine and L-alanyl-L-alanine in water using ab initio methods

Hacettepe Journal of Biology and Chemistry ◽

10.15671/hjbc.20144210862 ◽

2014 ◽

Vol 2 (42) ◽

pp. 263-263

Author(s):

Farhoush Kiani ◽

Mahmoud Tajbakhsh ◽

Fereydoon Ashrafi ◽

Nesa Shafiei ◽

Azar Bahadori ◽

...

Keyword(s):

Ab Initio ◽

Dissociation Constants ◽

Ab Initio Methods ◽

Acidic Dissociation

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Study of the structure and stability of aqua ions La(H2O) n 3+ (n = 8, 9) by ab initio methods

Russian Journal of Inorganic Chemistry ◽

10.1134/s0036023608080172 ◽

2008 ◽

Vol 53 (8) ◽

pp. 1249-1255 ◽

Cited By ~ 2

Author(s):

V. Yu. Buz’ko ◽

I. V. Sukhno ◽

M. B. Buz’ko ◽

A. A. Polushin ◽

V. T. Panyushkin

Keyword(s):

Ab Initio ◽

Ab Initio Methods ◽

Structure And Stability

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Gas-Phase Tautomerism in the Triazoles and Tetrazoles: A Study by Photoelectron Spectroscopy and ab Initio Molecular Orbital Calculations

Zeitschrift für Naturforschung A ◽

10.1515/zna-1981-1121 ◽

1981 ◽

Vol 36 (11) ◽

pp. 1246-1252 ◽

Cited By ~ 45

Author(s):

Michael H. Palmer ◽

Isobel Simpson ◽

J. Ross Wheeler

Keyword(s):

Ab Initio ◽

Gas Phase ◽

Molecular Orbital ◽

Photoelectron Spectroscopy ◽

Relative Stability ◽

Photoelectron Spectra ◽

Equilibrium Geometry ◽

Molecular Orbital Calculations ◽

Methyl Derivatives

The photoelectron spectra of the tautomeric 1,2,3,- and 1,2,4-triazole and 1,2,3,4-tetrazole systems have been compared with the corresponding N-methyl derivatives. The dominant tautomers in the gas phase have been identified as 2 H-1,2,3-triazole, 1 H-1,2,4-triazole and 2H-tetrazole.Full optimisation of the equilibrium geometry by ab initio molecular orbital methods leads to the same conclusions, for relative stability of the tautomers in each of the triazoles, but the calculations wrongly predict the tetrazole tautomerism.

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