The observation of spiral growth-steps in <i>n</i> -paraffin single crystals in the electron microscope

Abstract

Abstract Electron micrographs of single crystals of the n-paraffin, n-hexatriacontane, C36H74, show clearly the successive monomolecular steps on the growing face of the crystal. Examination of the edge of these molecular steps shows, in many crystals, not a succession of closed terraces, but a continuous spiral on the crystal face. The results thus afford direct visual confirmation of the theory of crystal growth by spiral growth-steps ending on screw dislocations. There is no evidence of the long-range migration of molecules over the growing face of the crystals. The molecules appear to condense only on the developing edge.