SKM 2023 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

O: Fachverband Oberflächenphysik

O 19: Poster: Ultrafast Electron Dynamics at Surface and Interfaces I

O 19.3: Poster

Montag, 27. März 2023, 18:00–20:00, P2/EG

Excited state photoemission momentum maps from time-dependent density functional theory — •Melvin Hodžić, Christian S. Kern, Andreas Windischbacher, and Peter Puschnig — Institute of Physics, NAWI Graz, University of Graz, Austria

Angle-resolved photoemission spectroscopy is a powerful experimental technique to reveal the electronic structure of thin films and interfaces. In particular, constant binding energy angular distributions, so called momentum maps, have been shown to be related to the Fourier transform of the electron-emitting initial state molecular orbital, thereby bridging experiment and theory in photoemission orbital tomography (POT). The extension of POT to optically excited states has, of late, been demonstrated via a femtosecond pump-probe setup, paving the way for tracing the momentum distribution of electrons on ultrafast time scales. However, linking the measured momentum maps to the spatial structure of the exciton wave functions has yet to be achieved. We propose a simple procedure which involves a coherent sum of the ground-state Kohn-Sham orbitals that construct the exciton wave function. Here, we validate this approach by solving Casida's equation for a series of organic molecules in the gas phase leading to optical absorption spectra and exciton compositions. With the gained information, momentum maps obtained via linear-response TDDFT are cross-checked by directly simulating angle-resolved photoemission spectra within the framework of real-time TDDFT. To this end, we record the flux of the emitted electrons through a detector surface.