scholarly journals Ultrafast electron energy-dependent delocalization dynamics in germanium selenide

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Zhesheng Chen ◽  
Heqi Xiong ◽  
Hao Zhang ◽  
Chaofeng Gao ◽  
Yingchun Cheng ◽  
...  
Keyword(s):  
Electronic State ◽  
High Energy ◽  
Final States ◽  
Layered Semiconductor ◽  
Charge Delocalization ◽  
Germanium Selenide ◽  
Core Electrons ◽  
Ultrafast Devices ◽  
Ultrafast Charge Transfer ◽  
Energy Dependent

AbstractUltrafast scattering process of high-energy carriers plays a key role in the performance of electronics and optoelectronics, and have been studied in several semiconductors. Core-hole clock spectroscopy is a unique technique for providing ultrafast charge transfer information with sub-femtosecond timescale. Here we demonstrate that germanium selenide (GeSe) semiconductor exhibits electronic states-dependent charge delocalization time by resonant photo exciting the core electrons to different final states using hard-x-ray photoemission spectroscopy. Thanks to the experiment geometry and the different orbital polarizations in the conduction band, the delocalization time of electron in high energy electronic state probed from Se 1s is ~470 as, which is three times longer than the delocalization time of electrons located in lower energy electronic state probed from Ge 1s. Our demonstration in GeSe offers an opportunity to precisely distinguish the energy-dependent dynamics in layered semiconductor, and will pave the way to design the ultrafast devices in the future.

Rearrangement collisions: two-particle exchange

1964 ◽  
Vol 277 (1369) ◽  
pp. 206-213 ◽  
Keyword(s):  
Energy Dependence ◽  
Cross Section ◽  
Born Approximation ◽  
High Energy ◽  
Electron Exchange ◽  
Final States ◽  
Particle Exchange ◽  
Exchange Cross Section

It is shown that the first Bom approximation for the exchange of two uncorrelated electrons should vanish. A formalism for the T matrix is presented which has this property. The high-energy result for the two-electron exchange cross-section previously calculated in first Born approximation behaves like E -7 . This result is in error due to a lack of orthogonality of initial and final states. When this is corrected the result for uncorrelated electrons has an energy dependence E -11 . The introduction of correlation gives terms behaving like E -10 which cannot be calculated unam biguously.

Optical properties of orthorhombic germanium selenide: an anisotropic layered semiconductor promising for optoelectronic applications

2021 ◽  
Author(s):  
Agata Karolina Tołłoczko ◽  
Szymon J. Zelewski ◽  
Michał Błaszczak ◽  
Tomasz Woźniak ◽  
Anna Siudzińska ◽  
...  
Keyword(s):  
Optical Properties ◽  
Optical Absorption ◽  
Van Der Waals ◽  
Group Iv ◽  
Black Phosphorus ◽  
Layered Semiconductor ◽  
Germanium Selenide ◽  
Optoelectronic Applications ◽  
High Optical Absorption

Group-IV monochalcogenides, such as germanium selenide (GeSe) are strongly anisotropic semiconducting van der Waals crystals isoelectronic to black phosphorus, with superior stability in air conditions. High optical absorption, good conductivity,...

scholarly journals Ultrafast charge transfer dynamics in 2D Covalent Organic Frameworks/Re-complex hybrid photocatalyst for CO2 reduction: hot electrons vs. cold electrons

2021 ◽  
Author(s):  
Qinying Pan ◽  
Mohamed Abdellah ◽  
Yuehan Cao ◽  
Yang Liu ◽  
Weihua Lin ◽  
...  
Keyword(s):  
Excited State ◽  
Charge Transfer ◽  
Excitation Energy ◽  
Co2 Reduction ◽  
Underlying Mechanism ◽  
High Energy ◽  
Hot Electrons ◽  
Covalent Organic Frameworks ◽  
Energy Excitation ◽  
Energy Dependent

Abstract Rhenium(I)-carbonyl-diimine complexes are promising photocatalysts for CO2 reduction. Covalent organic frameworks (COFs) can be perfect sensitizers to enhance the reduction activities. Here we investigated the excited state dynamics of COF (TpBpy) with 2,2'-bipyridine incorporating Re(CO)5Cl (Re-TpBpy) to rationalize the underlying mechanism. The time-dependent DFT calculation first clarified excited state structure of the hybrid catalyst. The studies from transient visible and infrared spectroscopies revealed the excitation energy-dependent photo-induced charge transfer pathways in Re-TpBpy. Under low energy excitation, the electrons at the LUMO level are quickly injected from Bpy into ReI center (1–2 ps) followed by backward recombination (13 ps). Under high energy excitation, the hot-electrons are first injected into the higher unoccupied level of ReI center (1–2 ps) and then slowly relax back to the HOMO in COF (24 ps). There also remains long-lived free electrons in the COF moiety. This explained the excitation energy-dependent CO2 reduction performance in our system.

European Energy Security and Sustainability

2011 ◽  
pp. 38-67
Author(s):  
Anatoly Zhuplev ◽  
Dmitry A. Shtykhno
Keyword(s):  
Energy Security ◽  
Oil And Gas ◽  
Sustainable Energy ◽  
High Energy ◽  
Energy Sector ◽  
Technology Investment ◽  
Regional Energy ◽  
Political Economic ◽  
Energy Dependent ◽  
The Eu

Europe’s economic wellbeing and growth are highly energy dependent and heavily reliant on Russian imports of oil and gas. European energy security, its alternatives, and implications are examined in this chapter with the view of sustainability and the EU-Russian energy dialog. With an asymmetric mutual political-economic interdependency with Russia, Europe’s exposure in oil and gas calls for sustainable energy solutions. Meantime, Russia, the key energy supplier in the European region, is also a major energy consumer whose economy is characterized by high energy intensity. Russian energy sector needs serious improvements in technology, investment, and management: failure to address these priorities erodes Russia’s reliability as major regional energy supplier. The chapter explores the dynamics of Russian energy sector and implications for European energy security and sustainability.

scholarly journals X-ray Spectral Evolution of High Energy Peaked Blazars

Galaxies ◽  
2020 ◽  
Vol 8 (3) ◽  
pp. 62
Author(s):  
Haritma Gaur
Keyword(s):  
High Energy ◽  
Energy Interval ◽  
Spectral Studies ◽  
Parabolic Model ◽  
Spectral Evolution ◽  
Spectral Variability ◽  
Spectral Parameters ◽  
X Ray ◽  
Wide Energy ◽  
Energy Dependent

The synchrotron hump of the high energy peaked blazars generally lies in the 0.1–10 keV range and such sources show extreme flux and spectral variability in X-ray bands. Various spectral studies showed that the X-ray spectra of high energy peaked blazars are curved and better described by the log-parabolic model. The curvature is attributed to the energy dependent statistical acceleration mechanism. In this work, we review the X-ray spectral studies of high energy peaked blazars. It is found that the log-parabolic model well describes the spectra in a wide energy interval around the peak. The log-parabolic model provides the possibility of investigating the correlation between the spectral parameters derived from it. Therefore, we compiled the studies of correlations between the various parameters derived from the log-parabolic model and their implications to describe the variability mechanism of blazars.

Energy-dependent nebula extent and spatially resolved spectra of the pulsar wind nebula 3C 58

2020 ◽  
Vol 498 (2) ◽  
pp. 1911-1919
Author(s):  
Fang-Wu Lu ◽  
Quan-Gui Gao ◽  
Li Zhang
Keyword(s):  
Surface Brightness ◽  
Spectral Energy Distribution ◽  
High Energy ◽  
Spatial Variations ◽  
Spectral Energy ◽  
X Ray ◽  
Spatially Resolved ◽  
Photon Index ◽  
Pulsar Wind ◽  
Energy Dependent

ABSTRACT 3C 58 is a pulsar wind nebula (PWN) that shows an interesting energy-dependent nebula extent and spatial variations of the photon index and surface brightness in the X-ray band. These observations provide useful information with which to study the spatially dependent radiative cooling of electrons and the energy-dependent transport mechanisms within the nebula. In this paper, the energy-dependent nebula extent and spatially resolved spectra of this PWN are investigated in the framework of a spatially dependent particle transport model. The observations of the nebula, including the photon spectral energy distribution, spatial variations of the X-ray spectrum, and measurements of the nebula extent, can be naturally explained in this model. Our results show that the energy-dependent nebula extent favours an advection–diffusion scenario with advection-dominated transport, and the variations of the nebula extent with energy in the X-ray band can be attributed to the cooling losses of high-energy electrons affected by synchrotron burn-off. Particle diffusion plays an important role in modifying the spatial variations of the photon index and surface brightness in the X-ray band. The radial extents of the nebula at radio, GeV and TeV energies are predicted by the model, indicating that the nebula extent of 3C 58 varies with energy in these bands. The analyses show that the dependence of the adiabatic cooling rate and synchrotron radiation on the spectral index of injected particles is important for changing the nebula extent at different energies.

scholarly journals Modelling pp, pA and AA in Pythia8

2019 ◽  
Vol 208 ◽  
pp. 11003
Author(s):  
Leif Lönnblad
Keyword(s):  
Heavy Ions ◽  
Model Building ◽  
High Energy ◽  
Final States ◽  
New Model ◽  
High Energy Collisions ◽  
Hadronic Final States ◽  
Fritiof Model

We present a new model for generating complete exclusive hadronic final states in high energy collisions involving heavy ions. The model is called Angantyr and is inspired by the old Fritiof model, building on the concept of wounded nucleons.

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