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O: Fachverband Oberflächenphysik
O 19: Poster: Ultrafast Electron Dynamics at Surface and Interfaces I
O 19.7: Poster
Monday, March 27, 2023, 18:00–20:00, P2/EG
Disentangling HOMO and LUMO excitation in momentum space by means of time-resolved photoemission orbital tomography — Alexa Adamkiewicz1, Miriam Raths2, •Marcel Theilen1, Monja Stettner2, Sabine Wenzel2, Mark Hutter2, Sergey Soubatch2, Christian Kumpf2, Francois C. Bocquet2, Robert Wallauer1, F. Stefan Tautz2, and Ulrich Höfer1 — 1Philipps-University Marburg, Germany — 2Peter Grünberg Institute (PGI-3), Jülich Research Centre, Germany
Time-resolved photoemission orbital tomography allows to trace electron dynamics in momentum space by measuring the angle-resolved photoemission intensity on an ultrafast timescale. For molecule-metal interfaces it proved to be a powerful technique to investigate the population dynamics of molecular states [1]. Here, we find for a well-ordered monolayer of CuPc on Cu(001)-2O a delay-dependent change in the momentum pattern of the molecular LUMO. In addition, we show how the temporal evolution of the momentum distribution can be systematically disentangled from contributions of the projected HOMO by varying the pump photon energy and polarization. By aligning the polarization of the pump pulse along the molecular axis of CuPc molecules, we are able to selectively excite molecules of a specific orientation. The temporal evolution of the excitation and decay from the LUMO can be well described by solving the optical Bloch equations for a three-level system.
[1] R. Wallauer et al., Science 371, 1056-1059 (2021).