Regensburg 2025 – scientific programme
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O: Fachverband Oberflächenphysik
O 73: Poster Metal and Semiconductor Substrates: Adsorption and Reactions of Small Molecules
O 73.5: Poster
Wednesday, March 19, 2025, 18:00–20:00, P2
N heteroatom effects in large aromatic physisorbed adsorbates on metal surfaces: azabenzopyrene on Cu(111) — •Henry Thake1, Matthew Stoodley1,2, David A. Duncan2,3, and Reinhard J. Maurer1 — 1University of Warwick, UK — 2Diamond Light Source, UK — 3University of Nottingham, UK
Conjugated molecules at metal surfaces are bound by a subtle balance of short- and long-range interactions including charge transfer and dispersion interactions. As such, they represent a challenging opportunity to improve approximations to density functional theory (DFT) where accurate structural and spectroscopic benchmark measurements exist. Accurate structural predictions of the large aromatic molecules naphthalene and pyrene have shown weak adsorption in a flat geometry on Cu(111). Here, we present a combined computational and experimental study of a closely-related molecule featuring a single nitrogen heteroatom - azabenzopyrene on Cu(111). Based on DFT calculations, x-ray standing wave (XSW) structural characterisation, x-ray photoelectron (XPS) and near-edge adsorption fine structure (NEXAFS) spectroscopy simulations, we study the effect of the heteroatom on the adsorption of the conjugated molecule. We develop a structural model consistent with XSW structure determination and simulate XPS and NEXAFS signatures of the sole nitrogen species in the molecule. Nitrogen 1s XPS and K-edge NEXAFS spectra present multiple co-existing chemical environments for the nitrogen species, for which we present a model hypothesis.
Keywords: Heteroatom; X-ray spectroscopy; Computational simulation; Surface defects