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O: Fachverband Oberflächenphysik

O 40: Ultrafast electron dynamics at surface and interfaces – Poster (joint session O/TT)

O 40.14: Poster

Dienstag, 10. März 2026, 14:00–16:00, P2

Hot-electron dynamics in moiré structures studied with resonant scanning tunneling spectroscopy — •Martin Lülff, Marta Przychodnia, Maciej Bazarnik, and Anika Schlenhoff — Institute of Physics, University of Münster, Germany

To study hot-electron dynamics in Gr-metal heterostructures, image-potential states (IPSs) serve as ideal model system. While their energies are known to be highly sensitive to the respective Gr-metal distance variation within the moiré unit cell [1, 2], recent two-photon photoemission experiments suggest moiré-site dependent lifetimes [3].

Here, utilizing the high spatial resolution of resonant scanning tunneling microscopy (STM) and spectroscopy (STS) we study the moiré-site dependent IPSs’ lifetimes for highly corrugated Gr/Fe/Ir(111) and Gr/Ir(111), respectively. Comparing these resonant STS data with those recorded on bare Fe/Ir(111) and Ir(111), respectively, enables the influence of the varying Gr-metal distance on the lifetimes to be distinguished from that of the underlying metal substrate. We analyse the IPSs’ lifetimes for a Stark shift in their energies by applying various electric field strengths in current-dependent STS series, and discuss the results in terms of their resulting energetic positions with respect to the underlying unoccupied electronic band structure. Our work contributes to an in-depth understanding of electron transfer processes at Gr-metal interfaces.
[1] M. Bazarnik and A. Schlenhoff, ACS Nano 19, 25812 (2025)
[2] N. Armbrust et al., New J. Phys. 17, 103043 (2015)
[3] N. Armbrust et al., Phys. Rev. Lett. 108, 056801 (2012)

Keywords: image-potential states; scanning tunneling spectroscopy; lifetimes; electronic structure; moiré structure