With Xiulan Li, Joshua Hihath, Bingqian Xu, Xiaoyin Xiao
We have measured single molecule conductance using a combined STM- and conducting AFM-based break junction method. The method works in aqueous solutions, which is suitable for biologically relevant molecules such as DNA and peptides, and also allows us to control electron transport through redox molecules with electrochemical gate. By oxidizing/reducing the redox molecules, the conductance can be changed over several orders of magnitude. Since the method relies on statistical analysis of a large number of measurements, it determines the most probable conductance of a single molecule covalently bound to electrodes, reproducibly. However, due to the large variations in the microscopic details of the individual molecular junctions, the conductance of certain molecules can take different values corresponding to different molecule-electrode contact geometries.
Purdue University, West Lafayette, IN