Dresden 2026 – scientific programme
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O: Fachverband Oberflächenphysik
O 4: Metal & Semiconductor substrates: Adsorption and reaction of small molecules I
O 4.1: Talk
Monday, March 9, 2026, 10:30–10:45, HSZ/0401
Increasingly incoherent: Effects of adatoms on the structure and characterisation of physisorbed aromatic molecules on Cu(111) — •Henry Thake1, Matthew Stoodley1,2, Mariia Radova1, David A. Duncan2,3, Lukas Hörmann4, and Reinhard J. Maurer1,4 — 1University of Warwick, UK — 2Diamond Light Source, UK — 3University of Nottingham, UK — 4University of Vienna, AT
X-ray standing wave (XSW) is a quantitative structural characterisation technique for hybrid metal-organic interfaces, providing species-dependent adsorption heights at picometer accuracy. Alongside adsorption heights, XSW measurements provide information on the coherence of the signal, directly related to the structural disorder of the overlayer. A series of recent XSW experiments on physisorbed poly-aromatic hydrocarbons (PAHs) revealed surprisingly low coherent fractions that are inconsistent with structural models produced by Density Functional Theory (DFT) calculations. In this talk, we investigate a hypothesis that this apparent increase in disorder may be related to molecular interactions with surface adatoms that are omnipresent at ambient conditions. Using a frozen transfer learned interatomic potential trained on DFT data of PAHs on Cu(111), we probe the influence of adatoms on dynamic adsorption at the interface. Spectroscopic measurements of these systems reveal perturbations in the electronic structure that are consistent with the co-adsorption of PAHs with adatoms. The inclusion of Cu adatoms to Cu(111) consistently increases the disorder for the PAHs, in line with XSW measurements.
Keywords: Adatom; X-ray spectroscopy; Machine learning; Work function; Potential energy surface