Dresden 2020 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 6: Organic Molecules on Inorganic Substrates I: Electronic, Optical and other Properties

O 6.8: Vortrag

Montag, 16. März 2020, 12:30–12:45, REC C 213

Unbaking a cake: Computational strategies to disentangle core-level spectroscopy signals of chemical interaction at metal-organic interfaces — •Samuel J. Hall and Reinhard J. Maurer — Department of Chemistry, University of Warwick, Coventry, CV4 7AL, United Kingdom

X-ray photo-emission spectroscopy (XPS) and x-ray absorption, so-called near-edge absorption fine structure spectroscopy (NEXAFS) provide insight into the structure, chemical interaction, and electronic properties of metal-organic interfaces. The interpretation of NEXAFS spectra is challenged by peak broadening, overlapping features and electronic hybridisation between organic and metallic states at the interface. These effects diminish the usefulness of reference spectra and literature values when it comes to peak assignment for complex metal-adsorbed molecules. In this talk, we will present a systematic computational study of the effect of molecule-metal interaction strength and overlayer structure on spectral features in NEXAFS spectroscopy. Using dispersion-inclusive Density Functional Theory and the Transition-Potential method, we have simulated NEXAFS spectra for a benchmark set of various aromatic organic compounds adsorbed on a series of (111) facets of single crystal transition metal surfaces. By decomposing the spectra into initial core state and final valence state contributions, we analyse how weak and strong molecule-metal interaction, charge transfer, and electronic hybridisation and dispersion effects manifest in spectra. On the basis of these findings, we provide suggestions for future interpretation strategies.