Reconciling XPS Simulations and Experiments: New Approaches to Quantify and Minimize Core Level Binding Energy Errors in the Development of New Standards

X-ray photoelectron spectroscopy is a cornerstone technique for materials characterization, providing crucial insights into elemental composition and chemical states. Accurately acquiring and interpreting XPS spectra remains challenging. Theoretical predictions can be a powerful tool to address some of these issues, but their accuracy and robustness need to be well quantified. This work introduces a novel approach to tackle this need by quantifying errors in theoretical core-level binding energy predictions, enhancing the synergy between theoretical and experimental XPS analysis. By employing internal references, the effect of experimental charge referencing errors is minimized, and systematic errors and method uncertainties are differentiated. This error quantification facilitates the optimization of computational methods and opens the door to the detection of inconsistencies in experimental data, ultimately leading to more accurate signal assignments and a deeper understanding of chemical environments.