Advantage of Electron Spectroscopic Diffraction on Calcified Tissue Sections

Abstract

Different stages in the mineralization of calcified tissues can be investigated by electron diffraction. A disadvantage is the strong background below the Debye—Scherrer rings caused by the large massthickness of calcified products and the high ratio (≃ 3) of the inelastic—to—elastic scattering cross—sections of the embedding material. Therefore, a large fraction of the background consists of inelastically scattered electrons with energy losses. The electron spectroscopic diffraction (ESD) mode of an energy—filtering microscope (ZEISS EM902) allows to record diffraction patterns using only the zero—loss electrons which consist of the primary beam, Bragg diffracted electrons and a smaller fraction of elastically scattered electrons between the Debye—Scherrer rings by thermal—diffuse scattering. Small—area diffraction patterns with different camera lengths are generated at the filter—entrance plane and the zero—loss electrons are selected by a slit in the energy—dispersive plane behind the Castaing—Henry filter lens.