Intervalley scattering in MoS\(_2\) imaged by two-photon photoemission with a high-harmonic probe

We report on the direct mapping of electron transfer in the momentum space of bulk MoS\(_2\) by means of time- and angle-resolved two-photon photoemission with a high-harmonic probe. For this purpose, we have combined a high-repetition rate high-harmonic source with tunable femtosecond pump pulses a...

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Bibliographic Details
Published in:arXiv.org 2016-10
Main Authors: Wallauer, Robert, Reimann, Johannes, Armbrust, Nico, Güdde, Jens, Höfer, Ulrich
Format: Article
Language:English
Subjects:
Charge transfer
Conduction bands
Decay
Dependence
Electron transfer
Excitation
Excitons
Femtosecond pulses
Helicity
Mapping
Photoelectric emission
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Summary:We report on the direct mapping of electron transfer in the momentum space of bulk MoS\(_2\) by means of time- and angle-resolved two-photon photoemission with a high-harmonic probe. For this purpose, we have combined a high-repetition rate high-harmonic source with tunable femtosecond pump pulses and a 3D (\(k_x, k_y, E\)) electron spectrometer. We show that optical excitation slightly above the A exciton resonance results in an immediate occupation of the conduction band at \(\overline{K}\) followed by an ultrafast transfer (\(< 50\)~fs) to the conduction band minimum at \(\overline{\Sigma}\). Both signals, at \(\overline{K}\) and \(\overline{\Sigma}\), do not vanish over the observed period of 400~fs. The technique described here enables direct access to the charge transfer dynamics in \(k\)-space and allows the study of decay times and decay channels in various systems with dependence on the excess energy or helicity of the excitation.
ISSN:2331-8422
DOI:10.48550/arxiv.1607.04999