Berlin 2018 – scientific programme
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O: Fachverband Oberflächenphysik
O 116: Focus Session: Structural Dynamics in Nanoscale Materials, Probed by Ultrafast Electron Pulses III
O 116.2: Talk
Friday, March 16, 2018, 11:00–11:15, HE 101
Ultrafast TEM: probing nanoscale dynamics with coherent electron pulses — •Armin Feist1, Nara Rubiano da Silva1, Thomas Danz1, Marcel Möller1, Nora Bach1, Katharina E. Priebe1, Murat Sivis1, Sascha Schäfer1,2, and Claus Ropers1 — 1IV. Physical Institute, Universität Göttingen, Göttingen, Germany — 2Institut für Physik, Universität Oldenburg, Oldenburg, Germany
Over the past decades, ultrafast techniques have shaped a rich picture of materials dynamics in spatially homogenous systems. Extending these concepts, ultrafast transmission electron microscopy (UTEM) combines the versatile imaging, diffraction and spectroscopy capabilities of state-of-the-art TEM with femtosecond temporal resolution achieved by a laser pump/electron probe scheme [1,2].
Here, we demonstrate local diffractive probing and phase-contrast imaging with nm-/fs- spatio-temporal resolution. The Göttingen UTEM instrument features photoemission from a nanoscale photocathode, delivering high coherence electron pulses of 0.6 eV energy width, down to sub-1 nm focal spot size, 200 fs pulse duration [2] and attosecond capability [3]. In particular, we employ ultrafast convergent beam electron diffraction (U-CBED) for the quantitative retrieval of the time- and space-dependent local deformation gradient tensor. Hereby, we map the optically induced acoustic lattice distortions, localized at the edge of a single-crystalline graphite thin film [4].
[1] A. H. Zewail, Science, 328, 187 (2010). [2] A. Feist et al., Ultramicroscopy, 176, 63 (2017). [3] K. E. Priebe, Nat. Photonics 11, 793 (2017). [4] A. Feist et al., arXiv: 1709.02805.