The imaging of As atoms in the surface dimers of (001)-c(2 x 8)/(2 x 4) surfaces, by inverting glancing-direction energy-dependent photo-electron diffraction spectra, was demonstrated. The glancing-direction geometry excluded most of the electrons which were emitted from the bulk, and enhanced the surface signal. Image reconstructions were presented which were based upon the Fourier inversion of experimental data, as well as on calculated energy-dependent photo-electron diffraction spectra. The Helmholz-Kirchhoff integral was shown to fail for measurements which were made at 1067eV. The vector Fourier transformation of energy-dependent photo-electron diffraction spectra was a direct structural tool. That is, it avoided trial-and-error methods and, together with the energy-dependent photo-electron diffraction data which were used in the simulations, permitted spatial resolutions of 0.06 to 0.1 to be obtained in the emitter scatterer direction.

H.Li, S.Y.Tong: Surface Science, 1993, 282, 380-8