The depth profile of core energy levels: Electronic structure of buried organic/metal interfaces examined by X-ray photoemission and target factor analysis

►A new method for depth profiling the core-energy levels of solid surfaces is presented. ► The angle-variation of the X-ray photoemission spectra is precisely derived. ► The data are transformed to core-energy levels vs. the depth from the surface. ► Energy levels of buried organic/metal interface were determined. ► The difference in C1s core level energies between the surface and bulk is 0.3 eV.