Categories, Break Junctions, and Structure

A group in England has developed a very nice idea based on fluctuations [31] here a molecule is chemisorbed on one end to a surface, and a conductive scanning tip is brought to within about a molecule length from the supporting metal. Thermal excitation then permits molecules to form instantaneous transport bridge structures between the planar support and the conductive electrode - one observes fluctuations 

The categories just described compromise the majority of the measurements on molecular transport junctions. 

It is possible to use electronic structure calculations combined with measurements in which the geometry is purposely varied to make some elegant deductions about the adsorption of molecules on the electrodes. A beautiful example is provided by work 

In general, however, many relevant geometric parameters are unknown in molecular transport junctions, and therefore it is necessary to make assumptions, and calculations, to help in understanding the geometry. One interesting approach is 

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