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Magneto-Raman scattering experiments from the surface of graphite reveal novel features associated to purely electronic excitations which are observed in addition to phonon-mediated resonances. Graphene-like and graphite domains are…

Mesoscale and Nanoscale Physics · Physics 2015-05-27 C. Faugeras , M. Amado , P. Kossacki , M. Orlita , M. Kühne , A. A. L. Nicolet , Yu. I. Latyshev , M. Potemski

The extraordinary electronic properties of graphene, such as its continuously gate-variable ambipolar field effect and the resulting steep change in resistivity, provided the main thrusts for the rapid advance of graphene electronics. The…

We study theoretically and numerically the conditions required for the appearance of a superradiance transition in graphene. The electron properties of graphene are described in the single $p_z$-orbital tight-binding approximation, in which…

Gamma-ray bursts (GRBs) appear as the brightest transient phenomena in the Universe. The nature of the central engine in GRBs is a missing link in the theory of fireballs to their stellar mass progenitors. Here it is shown that rotating…

Astrophysics · Physics 2008-11-26 Maurice H. P. M. van Putten

We present an electron projection imaging method to study the ultrafast evolution of photoelectron density distribution and transient fields near the surface. The dynamical profile of the photoelectrons from graphite reveals an origin of a…

Materials Science · Physics 2015-05-14 Ramani K. Raman , Zhensheng Tao , Tzong-Ru Han , Chong-Yu Ruan

We use ultrafast electron crystallography to study structural changes induced in graphite by a femtosecond laser pulse. At moderate fluences of ~< 21mJ/cm^2, lattice vibrations are observed to thermalize on a time scale of ~8ps. At higher…

Materials Science · Physics 2009-11-13 Ramani K. Raman , Yoshie Murooka , Chong-Yu Ruan , Teng Yang , Savas Berber , David Tománek

The transition from insulator to conductor can be achieved in some materials but requires modification of both the arrangement of atoms and their electronic configurations. This is often achieved by doping. Here we reveal a mechanism the…

We investigate the electron-positron pair cascade taking place in the magnetosphere of a rapidly rotating black hole. Because of the spacetime frame dragging, the Goldreich-Julian charge density changes sign in the vicinity of the event…

High Energy Astrophysical Phenomena · Physics 2018-11-14 Kouichi Hirotani , Hung-Yi Pu , Sabrina Outmani , Hsinhao Huang , Dawoon Kim , Yoogeun Song , Satoki Matsushita , Albert K. H Kong

The process of anion intercalation in graphite and its reversibility plays a crucial role in the next generation energy-storage devices. Herein the reaction mechanism of the aluminum graphite dual ion cell by operando X-ray scattering from…

Materials Science · Physics 2024-02-21 Giorgia Greco , Giuseppe Antonio Elia , Daniel Hermida-Merino , Robert Hahn , Simone Raoux

In the atmospheric pressure anodic carbon arc, ablation of the anode serves as a feedstock of carbon for production of nanomaterials. It is known that the ablation of the graphite anode in this arc can have two distinctive modes with low…

Plasma Physics · Physics 2021-12-22 Nirbhav S. Chopra , Yevgeny Raitses , Shurik Yatom , Jorge M. Muñoz Burgos

A plasma model is presented for the formation of ``cathode spots'' and subsequent crater development near field emission sites on a copper surface in the presence of a strong dc electric field. Adding to previously published models, we…

Accelerator Physics · Physics 2007-05-23 P. B. Wilson

We present ab initio many-body calculations of the optical absorption in bulk graphite, graphene and bilayer of graphene. Electron-hole interaction is included solving the Bethe-Salpeter equation on top of a GW quasiparticle electronic…

Materials Science · Physics 2015-05-14 Paolo E. Trevisanutto , Markus Holzmann , Michel Cote , Valerio Olevano

Persistent activity of magnetars is associated with electric discharge that continually injects relativistic particles into the magnetosphere. Large active magnetic loops around magnetars must be filled with outflowing particles that…

High Energy Astrophysical Phenomena · Physics 2015-06-03 Andrei M. Beloborodov

One of the most elusive features of Gamma Ray Bursts (GRBs) is the sporadic emission prior to the main prompt event observed in at least $\sim 15\%$ of cases. These precursors have spectral and temporal properties similar to the main prompt…

Scattering relativistic electrons with optical lasers can result in a significant frequency upshift for the photons, potentially producing $\gamma$-rays. This is what linear Compton scattering taught us. Ultra-intense lasers offer nowadays…

Plasma Physics · Physics 2019-06-05 Marija Vranic , Thomas Grismayer , Sebastian Meuren , Ricardo A. Fonseca , Luis O. Silva

In order to study properties of short carbon arcs, a self-consistent model was implemented into a CFD code ANSYS-CFX. The model treats transport of heat and electric current in the plasma and the electrodes in a coupled manner and accounts…

Plasma Physics · Physics 2020-08-13 J. Chen , A. Khrabry , I. D. Kaganovich , A. Khodak , V. Vekselman , H. -P. Li

We explore a one-zone hadronic model that may be able to reproduce $\gamma$-ray burst (GRB) prompt emission with a minimum of free parameters. Assuming only that GRBs are efficient high-energy proton accelerators and without the presence of…

High Energy Astrophysical Phenomena · Physics 2015-06-22 Maria Petropoulou , Stavros Dimitrakoudis , Apostolos Mastichiadis , Dimitrios Giannios

The evolution of a dilute electron-positron fireball is calculated in the regime of strong magnetization and very high compactness (l ~10^3-10^8). Heating is applied at a low effective temperature (< 25 keV), and the fireball is allowed to…

High Energy Astrophysical Phenomena · Physics 2015-06-17 Christopher Thompson , Ramandeep Gill

We calculate the very high energy (sub-GeV to TeV) inverse Compton emission of GRB afterglows. We argue that this emission provides a powerful test of the currently accepted afterglow model. We focus on two processes: synchrotron…

Astrophysics · Physics 2008-03-04 Yi-Zhong Fan , Tsvi Piran , Ramesh Narayan , Da-Ming Wei

We study the superconducting phase transition, both in a graphene bilayer and in graphite. For that purpose we derive the mean-field effective potential for a stack of graphene layers presenting hopping between adjacent sheets. For…

Superconductivity · Physics 2020-10-05 Lizardo H. C. M. Nunes , E. C. Marino , A. L. Mota