Local-field effects and electronic anisotropy of the (1×2) reconstructed Au(1 1 0) surface

The local-field theory is applied to the (1×1) and the (1×2) reconstructed (1 1 0) surfaces of noble metals. Calculated curves for the unreconstructed and reconstructed Au(1 1 0) surfaces are compared. In both cases, a dispersion-shaped profile is present at 2.55 eV. The spectrum for the (1×2) case shows a significantly stronger anisotropy than in the unreconstructed case. An experimental study has been made of the reflection anisotropy for the clean Au(1 1 0) surface at room temperature, where a (1×2) reconstruction is present, in order to test the validity of the calculations. The measured spectrum has a broad minimum in the range 2–4 eV with two sharp structures at 2.4 and 3.4 eV, respectively. The feature at 2.4 eV and the broad minimum is attributed to the effect of the screened local-field on d-band transitions at the surface. The influence of broadening and shifts in critical-point energies for the surface principal directions is discussed.