Orientation fluctuation of organic monomolecular layers at liquid/solid interfaces

To understand epitaxial crystal growth of organic molecules from solution, monomolecular layers of three isoindoline derivatives formed on the graphit e (0 0 0 1) surface from phenyloctane solutions were investigated by STM. T he observed images showed that the layer is composed of many relatively sma ller single crystalline domains than those formed by vacuum deposition. The two-dimensional lattice of the monomolecular layer of the isoindoline deri vative was analyzed with respect to the graphite surface lattice. In the ca se of isoindoline layers at the liquid/solid interface, the epitaxial orien tations were slightly fluctuated from domain to domain around commensurate orientation. It is called here "pseudo-commensurate" epitaxy. Such pseudo-c ommensurate epitaxy can be interpreted as resulting from the size effect; t hat is, broadening of Laue functions appearing in the lattice-lattice inter action equation at the interface of deposited layer and substrate surface. (C) 2001 Elsevier Science B.V. All rights reserved.