Dresden 2026 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 61: Organic molecules on inorganic substrates: electronic, optical and other properties II

O 61.1: Vortrag

Mittwoch, 11. März 2026, 15:00–15:15, HSZ/0201

Circular dichroism in the photoelectron angular distribution of achiral molecules — Christian Simon Kern¹, Xiaosheng Yang², Giovanni Zamborlini^1,3, Simone Mearini³, Matteo Jugovac³, Vitaliy Feyer³, Umberto De Giovannini⁴, Angel Rubio⁴, Serguei Soubatch², Michael G. Ramsey¹, •Frank Stefan Tautz², and Peter Puschnig¹ — ¹Institute of Physics, University of Graz, Austria — ²PGI-3, FZ Jülich & RWTH Aachen University, Germany — ³PGI-6, FZ Jülich & Universität Duisburg-Essen, Germany — ⁴MPI for the Structure and Dynamics of Matter, Hamburg, Germany

Circular dichroism in the angular distribution (CDAD) is the effect that the angular intensity distribution of photoemitted electrons depends on the handedness of the incident circularly polarized light. CDAD has been reported also for achiral organic molecules at the interface to metallic substrates. For this latter case, we investigate two prototypical pi-conjugated molecules, namely tetracene and pentacene, whose frontier orbitals have a similar shape but exhibit distinctly different symmetries. By comparing experimental CDAD momentum maps with simulations within time-dependent density functional theory, we show how the final state of the photoelectron must be regarded as the source of the CDAD in such otherwise achiral systems. We gain additional insight into the mechanism by employing a simple scattering model for the final state, which allows us to decompose the CDAD signal into partial wave contributions.

Keywords: angle-resolved photoelectron spectroscopy; circular dichroism; oligoacenes; time-dependent density functional theory