GROWTH-BEHAVIOR OF CRYSTAL FACES CONTAINING SYMMETRY-RELATED CONNECTED NETS - A CASE-STUDY OF NAPHTHALENE AND ANTHRACENE

The morphology of naphthalene and anthracene crystals has been studied both theoretically and experimentally. A connected net analysis shows that the faces {011} and (2<(11)over bar>) contain a pair of symmetry -related connected nets giving rise to a new phenomenon called symmetr y roughening. Experimentally the {011} and {2<(11)over bar>} faces hav e only been observed on naphthalene crystals grown from the vapor at v ery low driving forces. Upon increasing the driving force, the {011} f aces grow out very rapidly as flat faces at very low supersaturation, For anthracene these faces have never been observed. In this paper the relation between the connected net structure of crystal faces and the experimentally observed growth behavior is discussed.