New Photoelectron–Valence Electron Interactions Evident in the Photoelectron Spectrum of Gd2O–

2021 ◽  
Author(s):  
Jarrett L. Mason ◽  
Hassan Harb ◽  
Ali Abou Taka ◽  
Caleb D. Huizenga ◽  
Hector H. Corzo ◽  
...  
Keyword(s):  
Photoelectron Spectrum ◽  
Valence Electron ◽  
Electron Interactions

The Photoelectron Spectrum of 1-Bromonortricyclene

1985 ◽  
Vol 38 (1) ◽  
pp. 69 ◽  
Author(s):  
EW Della ◽  
PE Pigou ◽  
MK Livett ◽  
JB Peel
Keyword(s):  
Energy Range ◽  
Ab Initio ◽  
Molecular Orbital ◽  
Density Of States ◽  
Ionization Energy ◽  
Photoelectron Spectrum ◽  
Valence Electron ◽  
Alkyl Halide ◽  
High Density ◽  
Molecular Orbital Calculations

The He I photoelectron spectrum of 1-bromotricyclo[2.2.1.02.6] heptane (1- bromonortricyclene ) is compared with that of the parent alkane . Extensive conjugation between bromine and alkane orbitals in the low ionization-energy range produces a complex band pattern which is adequately described by ab initio valence-electron molecular orbital calculations. Consequently 1-bromo-nortricyclene presents a rare example of an alkyl halide in which the halogen character is neither highly localized nor smeared over a high density of states.

Photoelektronenspektren und Moleküleigenschaften, LXIV. Dimethyldiselenid — ein Beispiel für die Wechselwirkung zwischen benachbarten Elektronenpaaren / Photoelectron Spectra and Molecular Properties, LXIV. Dimethyldiselenide - an Example for the Interaction between Adjacent Electron Pairs

1976 ◽  
Vol 31 (12) ◽  
pp. 1616-1620 ◽  
Author(s):  
Galina Tschmutowa ◽  
Hans Bock
Keyword(s):  
General Model ◽  
Photoelectron Spectrum ◽  
Valence Electron ◽  
Lone Pair ◽  
Dimethyl Disulfide ◽  
Molecular Properties ◽  
Photoelectron Spectra ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Electron Pairs

The well-resolved helium(I) photoelectron spectrum of H3C-Se—Se-CH3 exhibits distinct bands corresponding to 11 of the total 13 valence electron ionizations. The unequivocal assignment is supported by EHMO calculations including spin/orbit coupling. The two selenium lone pair ionizations differ by 0.23 eV; a split observed also for dimethyl disulfide and discussed within a general model for interactions between adjacent lone pairs.

The Importance of Treating Electron-Electron Interactions in the Calculation of Dynamic Third-Order Polarizabilities for Linear Conjugated Polyenes

1987 ◽  
Vol 109 ◽  
Author(s):  
Brian M. Pierce
Keyword(s):  
Configuration Interaction ◽  
Valence Electron ◽  
Electronic Component ◽  
Third Order ◽  
Double Excitation ◽  
Conjugated Polyenes ◽  
Semi Empirical ◽  
Electron Interactions

ABSTRACTThe non-resonant electronic component of γ(-3ω ω, ω, ω) is calculated for ethylene, all-trans 1,3-butadiene, all-trans 1,3,5-hexatriene, and all-trans 1,3,5,7- octatetraene. The γ(-3ω; ω, ω, ω) is evaluated using the sum-over-states method and the all-valence-electron, semi-empirical INDO-SCF-MO procedure combined with single- and double-excitation configuration interaction (CI). The treatment of electron-electron interactions at the level of only single-excitation CI calculates negative values of γ(-3ω ω, ω, ω), which are in disagreement with measured positive values. The treatment of the interactions at the level of single- and double-excitation CI correctly calculates positive values for γ(-3ω ω, ω, ω). We conclude that the treatment of electron-electron interactions at least at the level of single- and double-excitation CI is needed to properly describe the dynamic thirdorder polarizabilities of linear conjugated polyenes, and related molecules with π-electron bonding networks.

Chemical Species Identification in an SEM by Changes in Emitted X-Ray Energies

1974 ◽  
Vol 32 ◽  
pp. 570-571
Author(s):  
R. H. Duff
Keyword(s):  
Species Identification ◽  
Valence Electron ◽  
Chemical Species ◽  
X Rays ◽  
Chemical Bonds ◽  
Small Shift ◽  
X Ray ◽  
Electron Transitions ◽  
Peak Energy ◽  
Chemical Combination

A material irradiated with electrons emits x-rays having energies characteristic of the elements present. Chemical combination between elements results in a small shift of the peak energies of these characteristic x-rays because chemical bonds between different elements have different energies. The energy differences of the characteristic x-rays resulting from valence electron transitions can be used to identify the chemical species present and to obtain information about the chemical bond itself. Although these peak-energy shifts have been well known for a number of years, their use for chemical-species identification in small volumes of material was not realized until the development of the electron microprobe.

Valence electron spectroscopy of inhomogeneous media

1992 ◽  
Vol 50 (2) ◽  
pp. 1150-1151
Author(s):  
A. Howie ◽  
D.W. McComb
Keyword(s):  
Specific Gravity ◽  
Loss Function ◽  
Electron Spectroscopy ◽  
Valence Electron ◽  
Peak Height ◽  
Loss Functions ◽  
Loss Peak ◽  
High Energies ◽  
Valence Electron Density ◽  
Electron Microscopist

The bulk loss function Im(-l/ε (ω)), a well established tool for the interpretation of valence loss spectra, is being progressively adapted to the wide variety of inhomogeneous samples of interest to the electron microscopist. Proportionality between n, the local valence electron density, and ε-1 (Sellmeyer's equation) has sometimes been assumed but may not be valid even in homogeneous samples. Figs. 1 and 2 show the experimentally measured bulk loss functions for three pure silicates of different specific gravity ρ - quartz (ρ = 2.66), coesite (ρ = 2.93) and a zeolite (ρ = 1.79). Clearly, despite the substantial differences in density, the shift of the prominent loss peak is very small and far less than that predicted by scaling e for quartz with Sellmeyer's equation or even the somewhat smaller shift given by the Clausius-Mossotti (CM) relation which assumes proportionality between n (or ρ in this case) and (ε - 1)/(ε + 2). Both theories overestimate the rise in the peak height for coesite and underestimate the increase at high energies.

Valence electron energy loss spectroscopy in reflection geometry

1989 ◽  
Vol 47 ◽  
pp. 378-379
Author(s):  
J. Liu ◽  
J. M. Cowley
Keyword(s):  
Energy Loss ◽  
Valence Electron ◽  
Interband Transition ◽  
Specular Reflection ◽  
Three Dimensional ◽  
Electron Excitation ◽  
Transmission Electron ◽  
Yield Information ◽  
Valence Bands ◽  
Excitation Processes

The low energy loss region of a EELS spectrum carries information about the valence electron excitation processes (e.g., collective excitations for free electron like materials and interband transitions for insulators). The relative intensities and the positions of the interband transition energy loss peaks observed in EELS spectra are determined by the joint density of states (DOS) of the initial and final states of the excitation processes. Thus it is expected that EELS in reflection mode could yield information about the perturbation of the DOS of the conduction and valence bands of the bulk crystals caused by the termination of the three dimensional periodicity at the crystal surfaces. The experiments were performed in a Philipps 400T transmission electron microscope operated at 120 kV. The reflection EELS spectra were obtained by a Gatan 607 EELS spectrometer together with a Tracor data acquisition system and the resolution of the spectrometer was about 0.8 eV. All the reflection spectra are obtained from the specular reflection spots satisfying surface resonance conditions.

A New Condition of Formation and Stablity of All Crystalline Systems in a Good Agreement with Experimental Data

2015 ◽  
Vol 11 (3) ◽  
pp. 3224-3228
Author(s):  
Tarek El-Ashram
Keyword(s):  
Experimental Data ◽  
Brillouin Zone ◽  
Electron Concentration ◽  
Free Electron ◽  
Lattice Point ◽  
Valence Electron ◽  
Fermi Gas ◽  
Valence Electron Concentration ◽  
Fermi Sphere ◽  
Good Agreement

In this paper we derived a new condition of formation and stability of all crystalline systems and we checked its validity andit is found to be in a good agreement with experimental data. This condition is derived directly from the quantum conditionson the free electron Fermi gas inside the crystal. The new condition relates both the volume of Fermi sphere VF andvolume of Brillouin zone VB by the valence electron concentration VEC as ;𝑽𝑭𝑽𝑩= 𝒏𝑽𝑬𝑪𝟐for all crystalline systems (wheren is the number of atoms per lattice point).

On the Linear Geometry of Lanthanide Hydroxide (Ln—OH, Ln=La-Lu)

2019 ◽  
Author(s):  
Hassan Harb ◽  
Lee Thompson ◽  
Hrant Hratchian
Keyword(s):  
Triple Bond ◽  
Density Functional ◽  
Valence Electron ◽  
Density Functional Theory Calculations ◽  
Electron Configuration ◽  
Functional Theory ◽  
Key Species ◽  
Pi Orbitals ◽  
Lanthanide Hydroxide ◽  
Linear Geometry

Lanthanide hydroxides are key species in a variety of catalytic processes and in the preparation of corresponding oxides. This work explores the fundamental structure and bonding of the simplest lanthanide hydroxide, LnOH (Ln=La-Lu), using density functional theory calculations. Interestingly, the calculations predict that all structures of this series will be linear. Furthermore, these results indicate a valence electron configuration featuring an occupied sigma orbital and two occupied pi orbitals for all LnOH compounds, suggesting that the lanthanide-hydroxide bond is best characterized as a covalent triple bond.

On the Linear Geometry of Lanthanide Hydroxide (Ln—OH, Ln=La-Lu)

2019 ◽  
Author(s):  
Hassan Harb ◽  
Lee Thompson ◽  
Hrant Hratchian
Keyword(s):  
Triple Bond ◽  
Density Functional ◽  
Valence Electron ◽  
Density Functional Theory Calculations ◽  
Electron Configuration ◽  
Functional Theory ◽  
Key Species ◽  
Pi Orbitals ◽  
Lanthanide Hydroxide ◽  
Linear Geometry

Lanthanide hydroxides are key species in a variety of catalytic processes and in the preparation of corresponding oxides. This work explores the fundamental structure and bonding of the simplest lanthanide hydroxide, LnOH (Ln=La-Lu), using density functional theory calculations. Interestingly, the calculations predict that all structures of this series will be linear. Furthermore, these results indicate a valence electron configuration featuring an occupied sigma orbital and two occupied pi orbitals for all LnOH compounds, suggesting that the lanthanide-hydroxide bond is best characterized as a covalent triple bond.

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