Second-layer surface core-level shift on Rh(111)

By synchrotron radiation high-resolution core-level photoemission we have found that the 3d(5/2) core-level spectrum of Rh(111) presents, in addition to a well resolved component shifted by -460 meV with respect to the bulk peak, also another component, opposit in sign, shifted by +71 meV. Photoelectron diffraction has allowed to attribute the two components to surface and sub-surface Rh atoms, respectively. Our findings are in very good agreement with recent ab initio density functional theory calculations and show that on Rh(111) initial state effects dominate over the screening contribution.