SKM 2023 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 83: Focus Session: Ultrafast Dynamics in Nanostructures II
O 83.6: Vortrag
Donnerstag, 30. März 2023, 16:45–17:00, GER 38
Structural Dynamics in Nanostructured Systems Probed by Ultrafast Transmission Electron Microscopy — •Nora Bach1, Armin Feist2, Marcel Möller2, Claus Ropers2, and Sascha Schäfer1 — 1Institute of Physics, University of Oldenburg, Germany — 2Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
One successful approach to investigate ultrafast nanoscale structural dynamics and to disentangle different excitation mechanisms in spatially inhomogeneous systems is based on local diffractive probing with nano-focused femtosecond electron pulses in an ultrafast transmission electron microscope (UTEM). Employing the Göttingen UTEM [1,2] in ultrafast convergent electron beam diffraction (U-CBED) mode [3], we study local dynamics in a multi-component model system consisting of a metal/semiconductor hybrid structure. Ultrashort optical excitation of a platinum stripe on a silicon membrane results in the generation of a multi-modal distortion wave propagating through the membrane. Pronounced lattice distortions are quantitatively tracked by U-CBED, and experimental results are reproduced by numerical simulations demonstrating that a superposition of Lamb waves at resonance frequencies of the bilayer structure [4] governs the evolution of the displacement inhomogeneity within the depth of the membrane.
[1] A. Feist, N. Bach, et al., Ultramicroscopy 176, 63 (2017).
[2] N. Bach et al., Struct. Dynamics 6, 014301 (2019).
[3] A. Feist et al., Struct. Dynamics 5, 014302 (2018).
[4] N. Bach et al., Struct. Dynamics 8, 035101 (2021).