Dresden 2017 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 75: Ultrafast Electron and Spin Dynamics
O 75.14: Vortrag
Mittwoch, 22. März 2017, 18:15–18:30, TRE Phy
Spatio-Temporal Probing of Lattice Dynamics in Graphite by Ultrafast TEM — •Armin Feist1, Nara Rubiano da Silva1, Wenxi Liang2, Claus Ropers1, and Sascha Schäfer1 — 1IV. Physical Institute - Solids and Nanostructures, Göttingen, Germany — 2Huazhong University of Science and Technology, Wuhan, China
Over the past decades, ultrafast techniques have shaped a rich picture of material dynamics in spatially homogenous systems. Extending these concepts, ultrafast transmission electron microscopy (UTEM) provides access to nanoscale processes on their intrinsic femtosecond time and nanometer length scales [1,2].
Here, we apply UTEM to investigate ultrafast nanoscale lattice dynamics localized at the edge of a single-crystalline graphite thin film [3]. Time-dependent convergent beam electron diffraction (CBED) of nanoscale sample areas gives access to the complex distortions of the crystal structure. Specifically, the initial optically generated, spatially-inhomogeneous strain distribution relaxes via coherent out-of-plane breathing and in-plane shear motion coupled to a propagating compressive strain wave. We spatio-temporally map these dynamics with 30 nm spatial and sub-picosecond temporal resolution. By employing UTEM, energy transfer and dissipation in complex nanostructured systems can be tracked over a wide range of time scales, spanning from femtosecond optical excitations to coherent lattice vibrations with nanosecond lifetimes.
[1] A. H. Zewail, Science, 328, 187 (2010). [2] A. Feist et al., arXiv: 1611.05022. [3] A. Feist et al., in preparation.