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Type: Congresso
Title: Effect Of High-optical Excitation On The Ultrafast Electron Dynamics In Stacked-monolayer Graphene Samples
Author: Castaneda
Juan A.; Rosa
Henrique Guimaraes; Gomes
Jose C. V.; Thoroh de Souza
Euzebio A.; de Brito Cruz
Carlos H.; Fragnito
Hugo L.; Padilha
Lazaro A.
Abstract: We report on transient absorption experiments performed at high optical excitation fluences and used to study the ultrafast dynamics in graphene. We employed a degenerated scheme of pump and probe at 800 nm (1.55 eV). The time resolution of our measurements was limited by the pulse duration similar to 100 fs. The samples were prepared by chemical vapor deposition (CVD) as single-layers on silica and, then staked layer-by-layer in order to make a stack of up to 5 graphene monolayers. We observed saturable absorption (SA) and fluence-dependent relaxation times. We see that the ultrafast carrier dynamics is composed by two decay mechanisms, one with response time of about 200 fs and a slower process of about 1 ps. The fast decay, due to both carrier-carrier and carrier-optical phonon scattering, becomes slower when the density of excited carrier was increased. We implemented a theoretical model and found that both the optical phonon rate emission and the optical phonon lifetime are affect by the pump fluence.
Subject: Ultrafast Spectroscopy
High-fluence Excitation
Saturation Absorption
Editor: Spie-Int Soc Optical Engineering
Rights: aberto
Identifier DOI: 10.1117/12.2235501
Date Issue: 2016
Appears in Collections:Unicamp - Artigos e Outros Documentos

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