scholarly journals Theoretical study of the ultrashort dynamics in graphene after fs-laser excitation

2019 ◽  
Vol 205 ◽  
pp. 05006 ◽  
Author(s):  
Krylow Sergej ◽  
Garcia Martin E.
Keyword(s):  
Decay Time ◽  
Theoretical Study ◽  
Laser Excitation ◽  
Low Frequency ◽  
Ultrafast Laser ◽  
Ab Initio Molecular Dynamics ◽  
Fast Decay ◽  
Phonon Modes ◽  
Fs Laser ◽  
Dynamics Simulations

We report on the calculation of the full dynamics of graphene after ultrafast laser excitation using ab-initio molecular dynamics simulations. Our calculations show a biexponential decay of the (100) and (110) Bragg peaks in time, similar to experimental results. Furthermore, we calculate the time-evolution of the phonon energies averaged over sets of phonons, chosen by their phonon frequencies. Our results suggest that the fast decay time can be accounted by phonon-phonon interactions rather than the generation of SCOPs. The slower decay time is governed by the equilibration of the system with low frequency phonon modes.

From Semiconductor to Metal in a Flash: Observing Ultrafast Laser-Induced Phase Transformations

1997 ◽  
Vol 481 ◽  
Author(s):  
J. P. Callan ◽  
A. M.-T. Kim ◽  
L. Huangt ◽  
E. N. Glezer ◽  
E. Mazur
Keyword(s):  
Phase Transformations ◽  
Dielectric Function ◽  
Spectral Range ◽  
Laser Excitation ◽  
Spectroscopic Technique ◽  
Ultrafast Laser ◽  
Lattice Heating ◽  
Fs Laser

ABSTRACTWe use a new broadband spectroscopic technique to measure ultrafast changes in the dielectric function of a material over the spectral range 1.5–3.5 eV following intense 70-fs laser excitation. The results reveal the nature of the phase transformations which occur in the material following excitation. We studied the response of GaAs and Si. For GaAs, there are three distinct regimes of behavior as the pump fluence is increased — lattice heating, lattice disordering, and a semiconductor-to-metal transition.

scholarly journals Decelerated lattice excitation and absence of bulk phonon modes at surfaces: Ultra-fast electron diffraction from Bi(111) surface upon fs-laser excitation

2019 ◽  
Vol 6 (6) ◽  
pp. 065101 ◽  
Author(s):  
V. Tinnemann ◽  
C. Streubühr ◽  
B. Hafke ◽  
T. Witte ◽  
A. Kalus ◽  
...  
Keyword(s):  
Electron Diffraction ◽  
Fast Electron ◽  
Laser Excitation ◽  
Phonon Modes ◽  
Fs Laser ◽  
Bulk Phonon

scholarly journals Proton Transport Mechanism and Pathways in the Superprotonic Phase of M3H(AO4)2 Solid Acids from Ab Initio Molecular Dynamics Simulations

2021 ◽  
Author(s):  
Boris Merinov ◽  
Sergey Morozov
Keyword(s):  
Molecular Dynamics ◽  
Ab Initio ◽  
Proton Transport ◽  
Transport Mechanism ◽  
Solid Acids ◽  
Ab Initio Molecular Dynamics ◽  
Theoretical Studies ◽  
Dynamics Simulations ◽  
Experimental And Theoretical Studies ◽  
Superprotonic Phase

The proton transport mechanism in superprotonic phases of solid acids is a subject of experimental and theoretical studies for a number of years. Despite this, details of the mechanism still...

scholarly journals Low-frequency optical phonon modes and carrier mobility in the halide perovskite CH3NH3PbBr3 using terahertz time-domain spectroscopy

2017 ◽  
Vol 111 (20) ◽  
pp. 201903 ◽  
Author(s):  
Daming Zhao ◽  
Jonathan M. Skelton ◽  
Hongwei Hu ◽  
Chan La-o-vorakiat ◽  
Jian-Xin Zhu ◽  
...  
Keyword(s):  
Time Domain ◽  
Optical Phonon ◽  
Carrier Mobility ◽  
Low Frequency ◽  
Terahertz Time Domain Spectroscopy ◽  
Phonon Modes ◽  
Time Domain Spectroscopy ◽  
Halide Perovskite

Ultrafast Laser Cleaning of Daguerreotypes

2011 ◽  
Vol 1319 ◽  
Author(s):  
Michael J. Abere ◽  
Ryan D. Murphy ◽  
Bianca Jackson ◽  
Gerard Mourou ◽  
Michel Menu ◽  
...  
Keyword(s):  
Material Removal ◽  
Silver Oxide ◽  
Laser Pulses ◽  
Silver Sulfide ◽  
Ultrafast Laser ◽  
Beam Diameter ◽  
Chemical Cleaning ◽  
Silver Substrate ◽  
Fs Laser ◽  
Lower Material

ABSTRACTAn ultrafast laser irradiation method for the removal of corrosion from Daguerreotypes without detrimentally affecting image quality has been developed. Corrosion products such as silver oxide and silver sulfide may be removed by chemical cleaning but these reactions are hard to control and are often damaging to the underlying silver, ruining the image. The Ti:Sapphire 150 fs laser pulses used in this study are focused to a beam diameter of 60 μm and are normally incident to the Daguerreotype. It was found that the corrosion layer has a lower material removal threshold than silver allowing for removal of corrosion with minimal removal of vital information contained in the silver substrate.

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