MOLECULAR ARRAYS AND MOLECULAR-STRUCTURE IN ORGANIC THIN-FILMS OBSERVED BY ELECTRON-MICROSCOPY

The value of electron microscopy in the study of organic crystals is r eviewed, together with its limitations in terms of radiation damage. T he mechanism of formation and growth of crystals on a substrate is dis cussed, on the basis of electron microscopic observations, of both sma ll crystals and the molecular structure of growth boundaries. Several examples of polycyclic hydrocarbons and phthalocyanines are described. A distinction is made between the information obtainable about disord er in a crystal, and precise measurements made by electron crystallogr aphy involving structural averaging.