Observation of strong surface state effects in the nonlinear   magneto-optical response of Ni(110)
  Spectroscopic magnetization induced optical Second Harmonic Generation (MSHG) measurements from a clean Ni(110) surface reveal strong resonance effects near 2.7 eV that can be attributed to the presence of an empty surface state. The good agreement with model calculations shows the potential of MSHG to probe spin polarized interface band structures. 
K. J. Veenstra, A. V. Petukhov, E. Jurdik and Th. Rasing