Molecular assembly on cylindrical surfaces

A molecule adsorbed on a metal surface carries an electric dipole moment, and diffuses on the surface. When a collection of identical molecules partially covers the surface, the dipole-dipole interactions, along with other thermodynamic forces, drive the molecules to aggregate into monolayer islands, in the shape of dots or stripes. The dipole-dipole interactions mediate through the electrostatic field in the space. If the space is shaped, the electrostatic field will be affected, and so will the molecular pattern. To illustrate this idea, we develop a model to evolve molecular pattern on the surface of a wire, or the inner surface of a tube. Molecules assemble into parallel rings on the wire, and parallel stripes on the internal surface of a tube. When the tube radius is comparable to, or smaller than, the island size, the stripes switch to the rings; occasionally, the stripes form spirals. (C) 2004 Elsevier Ltd. All rights reserved.