High-resolution electron microscopy of molecular crystals. II. Image simulation

Computer-simulated electron-microscope images have been produced for several different aromatic hydrocarbons, as well as the organometallic compound chlorinated copper phthalocyanine. Weak-phase-object images are compared with full multislice imaging calculations that include the resolution-limiting effects of limited spatial and temporal coherence; the comparisons indicate a considerable range of focus and thickness where intuitive image interpretation is possible. This favourable situation arises directly from the low atomic numbers of the atoms comprising the molecules and the almost monotonic fall-off with scattering angle of those structure factors within the resolution limit of the microscope. The occurrence and nature of both first- and second-order resolution-limiting effects on typical 100 and 500 kV images is also discussed.