Dispersion of Electronic Surface Resonances and Crystal Surface Structure

A new method of determining the lateral structure of crystal surfaces is described. The dispersion of electronic surface resonances at energies of the order of 10 eV above the vacuum level is measured, and the results are interpreted using a nearly free-electron method to determine low-index Fourier coefficients of the potential acting on electrons near the surface. The method is shown to reproduce the known lateral structure of $\mathrm{Ni}\mathrm{}\left(001\right)c(2\mathrm{}\times 2)\mathrm{O}$ surface.