DIRECT PHOTOELECTRON-DIFFRACTION METHOD FOR ADSORBATE STRUCTURAL DETERMINATIONS

A systematic search technique is proposed for low-energy photoelectron diffraction, which allows a direct determination of the bond axes from the emitter to the nearest backscatterers. It makes use of the fact that the Fourier transform of a photoelectron diffraction spectrum recorded in the scanned energy mode will show a maximum in the direction corresponding to a nearest-neighbor atom lying directly behind the emitter. The measurements are best performed with a large detector opening and a low energy resolution that allows short data accumulation times. Multiple-scattering calculations for a model system demonstrate that the position of the backscattering peak can be determined within an error of +/-3-degrees. This implies a spatial resolution perpendicular to the bond axis of about +/-0.1 angstrom, better than that achieved by holographic reconstruction techniques that use much larger amounts of experimental data.