Regensburg 2022 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 28: Organic Molecules at Surfaces 3: Theory

O 28.3: Vortrag

Dienstag, 6. September 2022, 11:00–11:15, S051

Impact of electron-phonon interaction on metal-organic interface states — •Lukas Eschmann, Jan Neuendorf, and Michael Rohlfing — Institut für Festkörpertheorie, Westfälische Wilhelms-Universität Münster, 48149 Münster, Germany

We discuss electron phonon interaction (EPI) in the context of metal-organic adsorbate systems and the occurring nearly-free electron-like interface states (IS) whose energy E is strongly coupled to the vertical binding distance d with a coupling strength of λ = Δ E/Δ d that is in the order of 1 eV/Å for several adsorbate systems.

We present an EPI model that is based on ab-initio data and uses the nearly-free electron-like character of the IS to obtain an analytic expression for the temperature induced renormalization of the latter^1,2. We find that the energy shift is dominated by the coupling to the out-of-plane phonon modes that change the average binding distance and scales quadratically with the coupling strength, i.e., ∼ λ². Applied to the system of a NTCDA layer adsorbed on Ag(111), our model predicts a renormalization of the IS onset energy through quantum mechanical coupling with the adsorbate phonons by −10 meV per 100 K. With this, we are able to explain the discrepancy between a classical lifting-effect and the experiment, thus revealing the important impact of EPI on spectroscopic states at metal-organic internal interfaces.

¹Eschmann, et al., Phys.Rev.B 104, L241102 (2021).

²Eschmann, et al., Phys.Rev.B 104, 245403 (2021).