PHOTOELECTRON HOLOGRAPHY - PROSPECTS AND LIMITATIONS OF DIRECT-METHODS

Images of near-surface atoms can be obtained from photoelectron diffra ction data by various imaging algorithms, the basic method being: (a) a Fourier transform over k-space involving a path-length difference ph ase factor. We will also discuss two recently proposed direct methods that compensate for the non-optical atomic scattering of photoelectron s: (b) a Fourier transform of small k-space cones centered on the appr oximately optical scattering regions of a photoelectron diffraction da ta set; and (c), a truly quantum mechanical Fourier transform that acc ounts for the non-optical propagation and atomic scattering of the pho toelectrons in the first Born approximation. Atomic images produced by these three methods are compared for photoelectron diffraction patter ns calculated from a single scattering Ni trimer, and a large multiple scattering Ni bulk cluster. All three methods are found to comparably resolve backscattering atomic images, while poorly resolving forward and side scattering atomic images.