Berlin 2018 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 83: Poster Focus Session: Structural Dynamics in Nanoscale Materials, Probed by Ultrafast Electron Pulses
O 83.7: Poster
Mittwoch, 14. März 2018, 18:15–20:30, Poster A
Ultrashort electron pulses in the space charge regime — •Nora Bach1, Till Domröse1, Armin Feist1, Claus Ropers1, and Sascha Schäfer1,2 — 14th Physical Institute, Georg-August-University, Göttingen, Germany — 2Institute of Physics, University of Oldenburg, Germany
Ultrafast transmission electron microscopy (UTEM) has become a powerful tool to investigate processes on the nanoscale with femtosecond temporal resolution [1]. The Göttingen UTEM is based on the modification of a commercial Schottky field emission TEM for which single-photon photoemission from a tip-shaped ZrO/W(100) emitter is employed. Spatial resolution down to the sub-nanometer regime and a spectral bandwidth of 0.6 eV is provided [2].
Here, we investigate the influence of the photoemitted electron density on the resulting transverse and longitudinal beam properties. For constant laser pulse duration, both emittance and energy width scale linearly with pulse charge. For increasing duration, however, both quantities decrease. Simulated results are in good agreement with the experimental data. The demonstrated high beam quality of the source and its tunability will enable new applications in the study of nanoscale ultrafast dynamics, including ultrafast electron holography and phase-contrast imaging.
[1] A. H. Zewail, Science 328, 187 (2010)
[2] A. Feist et al., Ultramicroscopy 176 (2016)