Electronic Tunnel Factors in Molecular Electron Transfer and Molecular Conduction

Abstract

Electron transmission through molecules and molecular interfaces has been a subject of intensive research owing to recent interest in electron transfer phenomena underlying the operation of the scanning tunneling microscope (STM) on one hand, and in the transmission properties of molecular bridges between conducting leads, on the other. In these processes, the traditional molecular view of electron transfer between donor and acceptor species give rise to a novel view of the molecule as a current carrying conductor, and observables such as electron transfer rates and yields are replaced by the conductivities, or more generally by current–voltage relationships, in molecular junctions. Such investigations of electrical junctions in which single molecules or small molecular assemblies operate as conductors, constitute a major part of what has become the active field of molecular electronics. In this chapter, the author reviews the current knowledge and understanding of this field with particular emphasis on theoretical issues, and on the relationship between this new look at electron transfer phenomena and the traditional study of molecular electron transfer in solution. Different approaches to computing the conduction properties of molecules and molecular assemblies are reviewed, and the relationships between them is discussed.

Electrochemical gating of single osmium molecules tethered to Au surfaces

“…While the rate of electron transfer is given by the Gerischer [30]-Marcus-Levich-Dogonadze-Kuznetzov expression [31][32][33] …”