Molecular detail in electron micrographs of quaterrylene C40H20

Abstract

The electron microscopy of organic compounds is beset by the problem of radiation damage due to the electron beam1. This radiation sensitivity is somewhat reduced in aromatic systems2 and organometallic complexes3–5 but it, nevertheless, limits the fineness of detail which can be resolved in images from these types of materials. Previous studies of the more stable compounds have concentrated on those where molecular superimposition normally occurred on a major crystallographic axis. The compound quaterrylene, C40H20, does not have such a projection axis and is therefore more typical of most organic crystals. We report here results from the examination of quaterrylene6 in the Cambridge University 600-kV high resolution electron microscope (HREM)7,8. These results provide direct information about intermolecular stacking and, after lattice averaging, show detail at the level of the six-membered aromatic rings within molecules of this material.