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arXiv · 2009.00721

Simultaneous Observation of Carrier-Specific Redistribution and Coherent Lattice Dynamics in 2H-MoTe$_{2}$ with Femtosecond Core-Level Spectroscopy

Andrew R. Attar·Hung-Tzu Chang·Alexander Britz·Xiang Zhang·Ming-Fu Lin·Aravind Krishnamoorthy·Thomas Linker·David Fritz·Daniel M. Neumark·Rajiv K. Kalia·Aiichiro Nakano·Pulickel Ajayan·Priya Vashishta·Uwe Bergmann·Stephen R. Leone
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Abstract

We employ few-femtosecond extreme ultraviolet (XUV) transient absorption spectroscopy to reveal simultaneously the intra- and interband carrier relaxation and the light-induced structural dynamics in nanoscale thin films of layered 2H-MoTe$_{2}$ semiconductor. By interrogating the valence electronic structure via localized Te 4$\textit{d}$ (39-46 eV) and Mo 4$\textit{p}$ (35-38 eV) core levels, the relaxation of the photoexcited hole distribution is directly observed in real time. We obtain hole thermalization and cooling times of 15$\pm$5 fs and 380$\pm$90 fs, respectively, and an electron-hole recombination time of 1.5$\pm$0.1 ps. Furthermore, excitations of coherent out-of-plane A$_{1g}$ (5.1 THz) and in-plane E$_{1g}$ (3.7 THz) lattice vibrations are visualized through oscillations in the XUV absorption spectra. By comparison to Bethe-Salpeter equation simulations, the spectral changes are mapped to real-space excited-state displacements of the lattice along the dominant A$_{1g}$ coordinate. By directly and simultaneously probing the excited carrier distribution dynamics and accompanying femtosecond lattice displacement in 2H-MoTe$_{2}$ within a single experiment, our work provides a benchmark for understanding the interplay between electronic and structural dynamics in photoexcited nanomaterials.

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Andrew R. Attar, Hung-Tzu Chang, Alexander Britz, Xiang Zhang, Ming-Fu Lin, Aravind Krishnamoorthy, Thomas Linker, David Fritz, Daniel M. Neumark, Rajiv K. Kalia, Aiichiro Nakano, Pulickel Ajayan, Priya Vashishta, Uwe Bergmann, Stephen R. Leone. 2020-09-01. Simultaneous Observation of Carrier-Specific Redistribution and Coherent Lattice Dynamics in 2H-MoTe$_{2}$ with Femtosecond Core-Level Spectroscopy. https://arxiv.org/abs/2009.00721

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