Computed electron microscope images of atomic defects in f.c.c. metals

The bright-field and dark-field electron microscope images expected for [100] split interstitials in thin crystals of gold and aluminum without and with lattice relaxation have been calculated by the method of periodic continuation including full n-beam dynamical interactions of both the Bragg reflections and the diffuse scattering. The advantage of using 1 MeV rather than 100 keV electrons is demonstrated in that, even with the same nominal resolution, the 1 MeV electrons give images in which the defect structure is more readily recognized. The conditions have been determined for which the defect images have high contrast and provide clear representations of the atom configurations.