Atomic structures by direct transform of diffraction patterns

We propose all the diffraction patterns can be directly transformed to prov ide three-dimensional atomic structures for the system studied. Depending o n the scattering process, either the holography or Patterson transform sche me is used. For diffraction patterns which are generated from a localized e mitter source or dominated by an inelastic-scattering feature like core-lev el photoelectron or low-energy Kikuchi electron, holography transform is ne eded. On the other hand, for diffraction patterns which were dominated by e lastic-scattering, like grazing-incidence X-ray diffraction, electron corre lated thermal diffuse scattering or low-energy electron diffraction curves, Patterson transform is needed. To prove our point, high-fidelity and artif act-free three-dimensional atomic structures obtained by transform of low-e nergy Kikuchi electron patterns and low-energy electron diffraction curves are presented. The future of these direct methods by transforming diffracti on patterns will be discussed. (C) 2001 Elsevier Science Ltd. All rights re served.