A model for the imaging of adsorbates on metal electrodes by the scanning tunneling microscope

We consider the interaction of the metal tip of a scanning tunneling micros cope with a metal electrode and a simple adsorbate. The tunneling current h as three contributions: direct electron exchange between the substrate and the tip, indirect exchange through the adsorbate, and an interference term. From a simple model Hamiltonian we obtain explicit expressions for these t hree terms, which indicate the dependence of the tunneling current on the e lectronic interactions and on the coupling to the solvent. (C) 2000 Elsevie r Science S.A. All rights reserved.