Berlin 2024 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 45: Ultrafast Electron Dynamics at Surfaces and Interfaces IV
O 45.9: Vortrag
Mittwoch, 20. März 2024, 12:30–12:45, MA 041
Modelling the temporal evolution of photoemission momentum maps of CuPc/Cu(001)-2O — •Alexa Adamkiewicz1, Miriam Raths2, Marcel Theilen1, Lasse Münster1, 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
Using time-resolved photoemission orbital tomography on a well-ordered monolayer of CuPc on Cu(001)-2O, we find a temporal evolution of the momentum pattern which gradually changes from a HOMO into a LUMO pattern [1]. This can be traced back to the presence of two excitation pathways with different dynamics: transient population of the CuPc LUMO via resonant HOMO→LUMO transition and coherent two-photon photoemission from the HOMO. For a theoretical description of the ultrafast electron dynamics, we numerically solve the optical Bloch equations for a three-level system, using a density matrix approach. This allows us to disentangle photoemission contributions from both excitation pathways. The model well reproduces the respective momentum distribution patterns as well as the measured shift in kinetic energy of photoelectrons for different detuning of the pump photon energy with respect to resonant excitation.
[1] A. Adamkiewicz et al., J. Phys. Chem. C 127, 20411 (2023).
Keywords: tr-POT; Organics; Interfaces