Within nanoscience, an emerging discipline is the study of the physics and chemistry of single molecules. Molecules may be considered as the ultimate building blocks, and are therefore interesting for the development of molecular devices and for surface functionalization. Thus, it is interesting to study their properties when adsorbed on a suitable substrate such as a solid or crystal surface, and also for their potential applications in nano- or molecular-electronics and nanosensing. Investigations have been made possible by the advent of high resolution surface imaging and characterization techniques, commonly referred to as Scanning Probe Microscopes.This book focuses on the fascinating properties of the single molecules, and the difference between single molecules and ensembles of molecules is emphasized. As the first book intended for graduate courses in the field, after each chapter, students should be able to answer the question: “What physical or chemical properties do you learn from a single molecule in this particular context?” Contributed by experts across the disciplines, the book provides useful reference material for specialized practitioners in surface science, nanoscience and nanoelectronics.

This book describes contemporary efforts to develop nano-molecular systems for future molecular electronics in which single molecules act as the basic elements in electrical circuits. While describing frontier research, it also gives a comprehensive introduction and discusses the related work being pursued worldwide. The book is composed of three parts. The first part describes the synthesis of novel molecules for molecular nano-systems. The second part deals mainly with nano-molecular systems on solid surfaces and the evaluation of the system with SPM. The third part reviews the theory required as a background for molecular electronics.

Recently, molecular electronics, especially that utilizing single molecules, has been attracting much attention. This is mainly because the theoretical limit is approaching in the present silicon-based technology, and the development of an alternative process is strongly desired. Single-molecule electronics is aimed at a breakthrough toward the next generation of computing systems. By designing and synthesizing highly functionalized molecules of nanometer size and incorporating these molecules into electrical circuits, we shall obtain much dense and high-speed processors. The concept of single-molecule electronics was first introduced by Aviram and Ratnar in 1978. In the early 1980s, many groups all over the world had started research on molecular electronics. At that time, single-molecule manipulation techniques had not been born, and the research was mainly carried out on molecular films formed by the Langmuir~Blodgett technique, a wet process, and by molecular-beam epitaxy, a dry process. A number of prototypes of switching devices and logic gates were, however, reported in the 1980s. In the early 1990s, scanning probe microscopes became popular and researchers obtained a single-molecule manipulation and evaluation tech nique. It became possible to fabricate practical devices using single molecules or small numbers of molecules. Finally, at the end of the last century, an explosion in the research field of single-molecule electronics was witnessed. In addition, studies of "biocomputing" started in the early 1980s and significant progress was achieved in the last century.