ABSTRACT
A clear understanding of the process of image formation in Scanning Tunneling Microscopy (STM) of disordered systems is necessary if the power of this technique is going to be used in the study of interfaces. STM owes its appeal mainly to its tremendous resolution, but molecular images are influenced by the tip-molecule interaction. Disorder is introduced by considering random distributions of the site energies in the molecular wire. The region with oscillations of the conductance corresponds to a resonance condition, where the energy of the tunneling electron coincides with an allowed energy of the combined electrode-wire system. The procedure is analogous to what one would do to calculate the conductance of a bundle of wires. The formalism is quite general and it fulfills the requirement of treating the electrodesample-electrode system as a single quantum unit where conduction is considered as a scattering process of electrons from one electrode to the other and through the sample.
