Single molecule electronics and electrochemistry Seminar

Measurement of the electrical properties of single molecules sandwiched between metal contacts has recently become an experimental reality. In recent years, we have developed and exploited novel scanning-tunnelling-microscopy-based methods for achieving this feat. In our methods, a gold substrate is coated with a low-coverage monolayer of molecules bearing two terminal thiol moieties, which interact strongly with gold. A gold STM tip is employed, and in the course of the experiments, one (or a few) molecule(s) forms a junction between tip and substrate, as illustrated schematically in Figure 1 (below). In one implementation, which we named the I(s) method, the tip is brought close to the surface (without making contact), then withdrawn while the junction conductance (Figure 1) is measured.

Using this and a related method (the I(t) technique) we have made several landmark findings in this high-profile area. Some of the following key issues affecting single molecule conductance will be discussed during the lecture: (1) Thermal effects on single molecular junctions. (2) Investigation of highly-transmissive molecular backbones. (3) Electrochemical switching and molecular conductance.