scholarly journals Probing the Electronic Structure of Bulk Water at the Molecular Lengthscale with Angle-Resolved Photoelectron Spectroscopy

2020 ◽  
Author(s):  
Samer Gozem ◽  
Robert Seidel ◽  
Uwe Hergenhahn ◽  
Evgeny Lugovoy ◽  
Bernd Abel ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Photoelectron Spectroscopy ◽  
Anisotropy Parameter ◽  
High Energy ◽  
Bulk Water ◽  
Low Energy ◽  
Water Molecules ◽  
Neat Water ◽  
Energy Regime ◽  
The Individual

<div>We report a combined experimental and theoretical study of bulk water photoionization. Angular distributions of photoelectrons produced by ionizing the valence band of neat water using X-ray radiation (250-750 eV) show a limited (<30 %) decrease in the beta anisotropy parameter compared to the gas phase, indicating that the electronic structure of the individual water molecules can be probed. By theoretical modeling using high-level electronic structure methods, we show that in a high-energy regime photoionization of bulk can be described as an incoherent superposition of individual molecules, in contrast to a low-energy regime where photoionization probes delocalized entangled states of molecular aggregates. The two regimes-low energy versus high energy-are defined as limiting cases where the de Broglie wavelength of the photoelectron is either larger or smaller than the intermolecular distance between water molecules, respectively. The comparison of the measured and computed anisotropies reveals that at high kinetic energies the observed reduction in beta is mostly due to scattering rather than rehybridization due to solvation.</div>

scholarly journals Probing the Electronic Structure of Bulk Water at the Molecular Lengthscale with Angle-Resolved Photoelectron Spectroscopy

2020 ◽  
Author(s):  
Samer Gozem ◽  
Robert Seidel ◽  
Uwe Hergenhahn ◽  
Evgeny Lugovoy ◽  
Bernd Winter ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Photoelectron Spectroscopy ◽  
Anisotropy Parameter ◽  
High Energy ◽  
Bulk Water ◽  
Low Energy ◽  
Water Molecules ◽  
Neat Water ◽  
Energy Regime ◽  
The Individual

<div>We report a combined experimental and theoretical study of bulk water photoionization. Angular distributions of photoelectrons produced by ionizing the valence band of neat water using X-ray radiation (250-750 eV) show a limited (<30 %) decrease in the beta anisotropy parameter compared to the gas phase, indicating that the electronic structure of the individual water molecules can be probed. By theoretical modeling using high-level electronic structure methods, we show that in a high-energy regime photoionization of bulk can be described as an incoherent superposition of individual molecules, in contrast to a low-energy regime where photoionization probes delocalized entangled states of molecular aggregates. The two regimes-low energy versus high energy-are defined as limiting cases where the de Broglie wavelength of the photoelectron is either larger or smaller than the intermolecular distance between water molecules, respectively.</div>

scholarly journals Probing the Electronic Structure of Bulk Water at the Molecular Lengthscale with Angle-Resolved Photoelectron Spectroscopy

2020 ◽  
Author(s):  
Samer Gozem ◽  
Robert Seidel ◽  
Uwe Hergenhahn ◽  
Evgeny Lugovoy ◽  
Bernd Abel ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Photoelectron Spectroscopy ◽  
Anisotropy Parameter ◽  
High Energy ◽  
Bulk Water ◽  
Low Energy ◽  
Water Molecules ◽  
Neat Water ◽  
Energy Regime ◽  
The Individual

<div>We report a combined experimental and theoretical study of bulk water photoionization. Angular distributions of photoelectrons produced by ionizing the valence band of neat water using X-ray radiation (250-750 eV) show a limited (<30 %) decrease in the beta anisotropy parameter compared to the gas phase, indicating that the electronic structure of the individual water molecules can be probed. By theoretical modeling using high-level electronic structure methods, we show that in a high-energy regime photoionization of bulk can be described as an incoherent superposition of individual molecules, in contrast to a low-energy regime where photoionization probes delocalized entangled states of molecular aggregates. The two regimes-low energy versus high energy-are defined as limiting cases where the de Broglie wavelength of the photoelectron is either larger or smaller than the intermolecular distance between water molecules, respectively. The comparison of the measured and computed anisotropies reveals that at high kinetic energies the observed reduction in beta is mostly due to scattering rather than rehybridization due to solvation.</div>

Surface Band Structure Studies of Si Rich Reconstructions on 4H-SiC(1-100)

2005 ◽  
Vol 483-485 ◽  
pp. 547-550 ◽  
Author(s):  
Konstantin V. Emtsev ◽  
Thomas Seyller ◽  
Lothar Ley ◽  
A. Tadich ◽  
L. Broekman ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Electron Diffraction ◽  
Photoelectron Spectroscopy ◽  
Low Energy ◽  
Ultraviolet Photoelectron Spectroscopy ◽  
Surface Band ◽  
X Ray ◽  
Low Energy Electron Diffraction ◽  
Different Temperatures ◽  
Low Energy Electron

We have investigated Si-rich reconstructions of 4H-SiC( 00 1 1 ) surfaces by means of low-energy electron diffraction (LEED), x-ray photoelectron spectroscopy (XPS), and angleresolved ultraviolet photoelectron spectroscopy (ARUPS). The reconstructions of 4H-SiC( 00 1 1 ) were prepared by annealing the sample at different temperatures in a flux of Si. Depending on the temperature different reconstructions were observed: c(2×2) at T=800°C, c(2×4) at T=840°C. Both reconstructions show strong similarities in the electronic structure.

Supracondylar fractures of the femur

2011 ◽  
Author(s):  
Wingrove T. Jarvis ◽  
Ananda M. Nanu
Keyword(s):  
High Energy ◽  
Fracture Pattern ◽  
Low Energy ◽  
Supracondylar Fractures ◽  
Advantages And Disadvantages ◽  
The Individual ◽  
Fractures Of The Femur ◽  
Surgical Option

♦ Supracondylar fractures of the femur are seen in the young (high energy) and the old (low energy). Both groups have their own specific problems♦ The advantages and disadvantages of each surgical option must be considered in relation to the individual patient and their fracture pattern.

The electronic structure and spin-charge separation of one-dimensional SrCuO2

2019 ◽  
Vol 33 (02) ◽  
pp. 1950006
Author(s):  
Huaisong Zhao ◽  
Jiasheng Qian ◽  
Sheng Xu ◽  
Feng Yuan
Keyword(s):  
Electronic Structure ◽  
Charge Separation ◽  
Energy Region ◽  
Doping Concentration ◽  
High Energy ◽  
Intermediate Energy ◽  
Low Energy ◽  
One Dimensional ◽  
High Energy Peak ◽  
Energy Peak

Based on the t-J model and slave-boson theory, we have studied the electronic structure in one-dimensional SrCuO2 by calculating the electron spectrum. Our results show that the electron spectra are mainly composed of three parts in one-dimensional SrCuO2, a sharp low-energy peak, a broad intermediate-energy peak and a high-energy peak. The sharp low-energy peak corresponds to the main band (MB) while the broad intermediate-energy peak and high-energy peak are associated with the shadow band (SB) and high-energy band (HB), respectively. From low-energy to intermediate-energy region, a clear two-peak structure (MB and SB) around the momentum [Formula: see text] appears, and the distance between two peaks decreases along the momentum direction from [Formula: see text] to [Formula: see text], then disappears at the critical momentum point [Formula: see text], leaving a single peak above [Formula: see text]. The electron spectral function in one-dimensional SrCuO2 is also the doping and temperature dependent. In particular, in the very low doping concentration, the HB merges into the MB. However, with the increases of the doping concentration, the HB separates from the MB and moves quickly to the high-binding energy region. The HB and MB are the direct results of the spin-charge separation while SB is the result of strong interaction between charge and spin parts. Therefore, our theoretical result predicts that the HB is more likely to be found at the low doping concentration, and it will be drowned in the background when the doping concentration is larger. Then with the temperature increases, the magnitude of the SB decreases, and it disappears at high temperature.

BBonding in minerals: the application of PAX (photoelectron and X-ray) spectroscopy to the direct determination of electronic structure

1989 ◽  
Vol 53 (370) ◽  
pp. 153-164 ◽  
Author(s):  
David S. Urch
Keyword(s):  
Electronic Structure ◽  
Valence Band ◽  
Photoelectron Spectroscopy ◽  
Direct Determination ◽  
Energy Scale ◽  
X Ray ◽  
Electron Transitions ◽  
Dipole Selection Rule ◽  
The Individual

AbstractX-ray photoelectron spectroscopy can be used to measure the ionization energies of electrons in both valence band and core orbitals. As core vacancies are the initial states for X-ray emission, a knowledge of their energies for all atoms in a mineral enables all the X-ray spectra to be placed on a common energy scale. X-ray spectra are atom specific and are governed by the dipole selection rule. Thus the individual bonding roles of the different atoms are revealed by the fine structure of valence X-ray peaks (i.e. peaks which result from electron transitions between valence band orbitals and core vacancies). The juxtaposition of such spectra enables the composition of the molecular orbitals that make up the chemical bonds of a mineral to be determined.Examples of this approach to the direct determination of electronic structure are given for silica, forsterite, brucite, and pyrite. Multi-electron effects and developments involving anisotropic X-ray emission from single crystals are also discussed.

σ Bonds: Electronic structure, photophysics, and photochemistry of oligosilanes

2003 ◽  
Vol 75 (8) ◽  
pp. 999-1020 ◽  
Author(s):  
H. A. Fogarty ◽  
D. L. Casher ◽  
Roman Imhof ◽  
T. Schepers ◽  
D. W. Rooklin ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Chain Length ◽  
Spectral Properties ◽  
Electronic States ◽  
Photochemical Reactions ◽  
Low Energy ◽  
Electron Systems ◽  
Current State ◽  
The Individual ◽  
Almost All

The making and breaking of σ bonds is an integral part of almost all photochemical reactions. Yet, the electronic states of σ electrons are not nearly as well understood as the states of π-electron systems. Efforts in our laboratory to enhance the current state of their understanding are described, using the specific example of oligosilanes. We address the intrinsically cyclic nature of σ delocalization and its dependence on chain length and conformation, both in terms of theory and spectroscopic experiments, from the simplest disilane chromophore to the spectral properties of the individual conformers of permethylated heptasilane. We also describe a new low-energy luminescence from certain conformers of permethylated oligosilanes.

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