The Role of Electronic and Phononic Excitation in the Optical Response of Monolayer WS2 after Ultrafast Excitation

Transient changes of the optical response of WS2 monolayers are studied by femtosecond broadband pump–probe spectroscopy. Time-dependent absorption spectra are analyzed by tracking the line width broadening, bleaching, and energy shift of the main exciton resonance as a function of time delay after...

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Bibliographic Details
Published in:Nano letters 2017-02, Vol.17 (2), p.644-651
Main Authors: Ruppert, Claudia, Chernikov, Alexey, Hill, Heather M, Rigosi, Albert F, Heinz, Tony F
Format: Article
Language:English
Subjects:
atomically thin 2D materials
carrier and phonon dynamics
INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
MATERIALS SCIENCE
ultrafast spectroscopy
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Summary:Transient changes of the optical response of WS2 monolayers are studied by femtosecond broadband pump–probe spectroscopy. Time-dependent absorption spectra are analyzed by tracking the line width broadening, bleaching, and energy shift of the main exciton resonance as a function of time delay after the excitation. Two main sources for the pump-induced changes of the optical response are identified. Specifically, we find an interplay between modifications induced by many-body interactions from photoexcited carriers and by the subsequent transfer of the excitation to the phonon system followed by cooling of the material through the heat transfer to the substrate.
ISSN:1530-6984
1530-6992
DOI:10.1021/acs.nanolett.6b03513