New experimental technique for determining real-space atomic images applied to aluminum adsorbed on silicon (111)

Abstract
The holographic principle is used to invert experimental photoelectron diffraction spectra to reveal the surface structure of Si(111)(√3 × √3 )-Al. The photon-energy dependence for the Al 2p emission intensity is measured for a set of emission angles. A new transformation method is applied to measured scanned-photon-energy photoemission spectra. The results of each inversion are summed over the set of angles giving images which clearly show the local geometry near the emitting atom, Al. Images are also obtained by theoretical simulation and agree well with experiment. The results demonstrate the technique as a direct, model-independent structural method, yielding bond distances and directions.