Interpretation of X-ray Absorption Spectroscopy in the Presence of Surface Hybridisation
Katharina Diller, Reinhard J. Maurer, Moritz Müller, Karsten Reuter, J. Chem. Phys. 146, 214701 (2017)
Accurate ab-initio core-level spectroscopy simulations of surface-adsorbed molecules reveal the details of surface hybridization.
The interpretation of X-ray absorption spectra of complex organic adsorbates on metal surfaces is challenged by the variety of contributing effects at the interface. On the example of 2H-porphine adsorbed on Ag(111) and Cu(111) substrates we show that explicitly accounting for the extended metal surface in density-functional theory (DFT) calculations allows a direct access to the two main effects of the molecule/surface interaction on XAS: (1) the substrate-induced chemical shift of the 1s core levels that dominates spectral changes in mainly physisorbed systems and (2) the hybridisation-induced broadening and loss of distinct resonances that dominates in more chemisorbed systems.