Regensburg 2022 – scientific programme
Parts | Days | Selection | Search | Updates | Downloads | Help
O: Fachverband Oberflächenphysik
O 68: Focus Session: Time-Resolved Momentum Microscopy
O 68.7: Talk
Thursday, September 8, 2022, 17:15–17:30, H3
Time-resolved photoemission orbital tomography of CuPc on Cu(001)-2O — •Alexa Adamkiewicz1, Miriam Raths2, Monja Stettner2, Francois C. Bocquet2, Christian Kumpf2, Robert Wallauer1, F. Stefan Tautz2, and Ulrich Höfer1 — 1Fachbereich Physik, Philipps Universität Marburg, Germany — 2Peter Grünberg Institute (PGI-3), Jülich Research Centre, Germany
Charge transfer across molecular interfaces is reflected in the population of electronic orbitals. For ordered organic layers, time-resolved photoemission orbital tomography (tr-POT) is capable of spectroscopically identifying the involved orbitals and deducing their population from the measured angle-resolved photoemission intensity with high temporal resolution. In a first example, we found that for PTCDA/ Cu(001)-2O, two distinct excitation pathways could be observed with visible light [1]. The parallel component of the electric field induces a direct HOMO-LUMO transition, the perpendicular component transfers a substrate electron into the molecular LUMO. While in this case, a distinct excitonic signature was not observed, changes in the momentum pattern can in general serve as a measure of detecting excitonic processes. Here, we show such time-dependent change of the pattern for CuPc/Cu(001)-2O. We demonstrate how the temporal evolution of the LUMO momentum distribution can be systematically disentangled from contributions of the projected HOMO. Moreover, we observe LUMO excitation of selected molecular orientation at normal incidence by aligning the pump polarization along the molecular axis. [1] R. Wallauer et al., Science 371, 1056 (2021).