Synthesis, Structure, and Properties of Model Organic Surfaces

Interest in the properties of thin-film organic materials, especially regard­ ing organized monoand multilayer assemblies, has grown enormously in recent years. The impetus for this renaissance-the relevance of such structures and materials to biological interfaces and membranes, corrosion protection, electrochemistry, wetting, adhesion, and microelectronic cir­ cuit fabrication, for example-has been discussed extensively (1,2). Such materials are clearly contributing significantly to our more general under­ standing of the physics and chemistry of complex surfaces and interfaces. In this article, we provide a general overview of areas in which this has been persuasively demonstrated and, in so doing, suggest the intellectual issues that drive current research in this field. Until recently, there were no generally applicable methods to construct well-ordered, organic surface phases by using any rational synthetic scheme. Metal, semiconductor, and oxide surfaces can be easily prepared by orienting, cutting (or cleaving), and polishing single-crystal substrates followed by cleaning in ultrahigh vacuum (URV) (i.e. by ion bom-