Regensburg 2022 – scientific programme
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O: Fachverband Oberflächenphysik
O 28: Organic Molecules at Surfaces 3: Theory
O 28.4: Talk
Tuesday, September 6, 2022, 11:15–11:30, S051
X-ray spectroscopic fingerprints of chemical bonding at molecule-metal interfaces revealed by first-principles core-level simulation — •Samuel J. Hall1, Benedikt P. Klein1,2, and Reinhard J. Maurer1 — 1Department of Chemistry, University of Warwick, Coventry, UK — 2Diamond Light Source, Harwell Science and Innovation Campus, Didcot, UK
Characterisation of the chemical environment and electronic structure of organic materials and metal-organic interfaces can be carried out with x-ray photoelectron spectroscopy (XPS) and near-edge x-ray absorption fine structure (NEXAFS) spectroscopy. The adsorption of molecules onto surfaces has been shown to change various spectral features which have previously been connected to changes in chemical bonding and charge distribution. However, these can be difficult to interpret due to overlapping features of multiple species and widely broadened spectra. Through the use of density functional theory (DFT) calculations we study two molecular isomers, azulene and naphthalene, adsorbed onto three metal (111) surfaces of silver, copper, and platinum. Categorised into three regimes of molecule-metal chemical bonding, we connect the changes seen in the spectra to the chemical bonding behaviour and decompose the signatures into initial core-state and final valence-state contributions. We analyse the effect of charge transfer, electronic hybridisation and dispersion effects, and aim to provide guidance for experimental spectral analysis.