The experimental determination of the conductance of single molecules

The measurement of the electrical properties of molecules, down to the single molecule level, has become an experimental reality in recent years. A number of methods are now available for experimentally achieving this feat. The common aim of these methods is to entrap a single or small numbers of molecules between a pair of metallic contacts. This topical review focuses on describing and comparing experimental methods for entrapping and measuring the electrical properties of single molecules in metallic contact gaps. After describing the methods, reasons are tendered for apparent discrepancies in the literature between measured single molecule conductance values, with a focus on the most widely studied alkanedithiol system. Illustrative examples are then presented of the determination of the electrical properties of a range of single molecular systems, in order to highlight the progress which has been made in recent years.