Berlin 2015 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 69: Ultrafast Electron and Spin Dynamics
O 69.10: Poster
Mittwoch, 18. März 2015, 18:15–21:00, Poster A
Correlation of Chirp and Delay in Attosecond Streaking Measurements from W Surfaces — •Andreas Kim1, Johannes Barth1, Peter Feulner1, Konrad Hütten1, Reinhard Kienberger1, Ferenc Krausz2, and Stefan Neppl3 — 1TU-München, Physikdepartment, Garching, Germany — 2MPI für Quantenoptik, Garching, Germany — 3LBNL, Berkeley, USA
Attosecond streaking, i.e., the momentum-modulation of photoelectrons emitted by ultrashort XUV pulses into the strong field of a synchronized IR laser [R. Kienberger et al., Nature 427, 817], enables chronoscopy on the attosecond timescale. It has been used to explore time delays between the release of photoelectrons from different electronic levels with unprecedented resolution, from isolated particles [e.g. M. Schultze et al., Science 328, 1658] and condensed matter [A. Cavalieri et al., Nature 449, 1029; S. Neppl et al., PRL 109, 087401]. This method also provides information on characteristic parameters of the ultrashort XUV pulses like duration, central energy and chirp, i.e., the temporal variation of the photon energy across the pulse. We measure a direct correlation between the wave-packet chirp and relative time delay between conduction band and W4f core-level photoemission, with different chirp values for conduction band and W4f electrons. We show that reliable information on the excitation pulse, the electronic transport and screening processes can only be derived from such attosecond streaking data, if detection and evaluation artifacts are identified and accounted for. Supported by the Deutsche Forschungsgemeinschaft (Munich Centre for Advanced Photonics; MAP B.1.3 & B.1.4)