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Preparation of Liquid-exfoliated Transition Metal Dichalcogenide Nanosheets with Controlled Size and Thickness: A State of the Art Protocol
Published on: December 20, 2016
Nonequilibrium dynamics of high energy transitions in monolayer WSe2
Oleg Dogadov1,2, Jorge Cervantes-Villanueva3, Nicholas Olsen4
1Department of Physics, Politecnico di Milano, Piazza Leonardo da Vinci 32, Milano 20133, Italy.
Abstract:
High-energy optical transitions in monolayer transition-metal dichalcogenides exhibit characteristics that are markedly distinct from those of lower-lying band-edge excitons. These differences arise from the involvement of electronic states located at regions of the Brillouin zone that are displaced from theKvalleys. In this work, we investigate the ultrafast dynamics of these high-energy excitations by employing broadband ultrafast transient absorption spectroscopy spanning the visible to ultraviolet spectral range. We observe that the formation and relaxation dynamics of one of the high energy transitions display a distinct behavior compared to the lower-energy excitonic resonances, developing on a significantly slower timescale. First-principles calculations of the excitonic landscape allow us to account for this delayed response and attribute it to the phonon-mediated formation of momentum-dark excitons.
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