Holographic reconstruction of Si(111) atom positions from energy- and angle-resolved photoelectron diffraction

Angle- and energy-resolved photoelectron diffraction patterns of Si(111) were measured for electron kinetic energies between 196 eV to 784 eV. The diffraction patterns were holographically reconstructed in order to obtain real-space atom images of the near-neighbor environment of the emitter. The reconstruction yields real atom positions in a plane parallel to the surface when the spherical electron-wave approximation is used. Also, maxima corresponding to no atom coordinates were found in the reconstruction. Less intense maxima as in the spherical electron-wave approximation were obtained if a complex scattering factor was included in the reconstruction algorithm. The atom images were calculated for different scattering factors used in the reconstruction. These results are compared with the images obtained for a phase-locked summation of the multiple-energy data. This directly demonstrates the sensitivity of the atom images on the phase in a holographic reconstruction from photoelectron diffraction data.