Speaker
Description
To understand reaction mechanisms in heterogenous catalysis, X-ray Photoelectron Spectroscopy (XPS) is a widely used characterization technique as it allows the identification of involved species based on core-level binding energies. This approach exploits the fact that electron core-level binding energies are highly sensitive to the local chemical environment, resulting in shifts upon changes in the adsorption geometry or conversion to a different chemical species. However, relating the observed core-level binding energy shifts to corresponding adsorption geometries is not straightforward, establishing the need for theoretical predictions for reliable interpretation.
The proposed poster reviews three methods for calculating core-level binding energies using density functional theory (DFT), namely the initial state, final state and Slater-Janak approach. The assumptions and expected performance of each method are compared, with special attention to additional information that can be obtained from such a comparison, for example on the relaxation energy contribution to the predicted core-level binding energies. In addition to providing accurate predictions, the potential of theoretical calculations for identifying the main factors contributing to core-level binding energy shifts is discussed. This eventually allows to establish simple principles for rationalizing shifts observed in experiments.
