DIRECT RETRIEVAL OF CRYSTAL-STRUCTURE FACTORS IN THEED

A linear model and a non-linear quadratic model for transmission high-energy electron diffraction (THEED) have been developed and applied to invert crystal structure factors directly from energy-filtered convergent beam electron diffraction (CBED) intensities. The models are based on perturbation theory of high-energy electron diffraction, and the unperturbated reference structure factors are constructed from an assembly of neutral atoms. The single and double diffraction approximations used in the linear and quadratic models are: shown to be good approximations for describing the redistributed charge scattering in crystals, and the inverted crystal structure factors are shown to be unique for all practical sample thicknesses used in THEED.