Measuring concentration depth profiles at liquid surfaces: Comparing angle resolved X-ray photoelectron spectroscopy and neutral impact collision scattering spectroscopy

► We compare concentration depth profiles at liquid surfaces determined with NICISS and ARXPS. ► Three different criteria were applied to compare the concentration depth profiles. ► Good agreement between the profiles was found for the surface excess. ► Good agreement was found for the length scale of most of the profiles. ► The separation of cation and anion can be measured with NICISS at low kinetic energies.