Photoinduced work function modifications and their effect on photoelectron spectroscopy

We investigate the effect of a spatially varying work function on photoemission experiments. It is demonstrated that a photoinduced work function change when probed by ultraviolet and two-photon photoemission spectroscopy can have pronounced effects on photoemission spectra. These effects are simulated by a simple model that reproduces the data remarkably well and allows for quantitative interpretation of the modified low energy region of the photoemission spectra. These findings are highly relevant when discussing work function determinations by photoemission spectroscopy and moreover may have substantial impact on the energy level alignment of molecule-metal or -semiconductor interfaces. (C) 2013 AIP Publishing LLC.