Surface versus bulk contributions to the Rashba splitting in surface systems

We report on a quantitative investigation on the Rashba effect in the Shockley state of the model system Ag/Au(111) by means of angle-resolved photoemission spectroscopy with high-energy resolution. The spectra are discussed in detail in comparison with results of one-step photoemission calculations. The systematic overestimation in the wave-vector splitting present in all actual theoretical studies is explained in terms of an insufficient description of the surface potential. Also, we conclude that the coupling between the semi-infinite bulk and the surface potential mediated by the bulk reflection matrix $B$ is of major importance for a quantitative description of the Rashba effect.