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O: Fachverband Oberflächenphysik
O 23: Poster Ultrafast Electron Dynamics
O 23.2: Poster
Montag, 17. März 2025, 18:00–20:00, P2
Ultrafast low-energy photoelectron diffraction for the study of surface-adsorbate interactions with 100 femtosecond temporal resolution — Hermann Erk1, Carl Erik Jensen1, •Stephan Jauernik1, and Michael Bauer1,2 — 1Institute of Experimental and Applied Physics, Kiel University, 24098 Kiel, Germany — 2Kiel Nano, Surface and Interface Science KiNSIS, Kiel University, 24118 Kiel, Germany
In this contribution a novel method of ultrafast electron diffraction for the study of structural dynamics at surfaces is presented. In our photoemission-based experiment we analyze the energy-momentum distribution of low-energy photoelectrons excited by a near ultraviolet (NUV) ultrafast laser pulse in graphite that are diffracted as they pass through an ordered tin-phthalocyanine adsorbate layer. The probing electron pulse is generated in the immediate vicinity of the surface. This limits the propagation distance of the electron pulse before diffraction to a few nanometers and thus minimizes pulse broadening effects due to space charge and dispersion. We experimentally demonstrate a time resolution of this ultrafast low-energy photoelectron diffraction (ULEPD) of about 100 fs [1], which is only limited by the pulse width of the NUV laser pulse and exceeds reported values of conventional ultrafast low-energy electron diffraction [2] by a factor of 10.
[1] H. Erk et al., Phys. Rev. Lett. 133, 226201 (2024)
[2] S. Vogelgesang et al., Nat. Phys. 14, 184 (2017)
Keywords: Ultrafast Photoelectron Diffraction; ARPES; Graphite; phthalocyanine