Vacuum tunneling current from an adsorbed atom

Abstract

The tunneling current density is computed in the vacuum region between two planar metal electrodes, on one of which is an adsorbed atom. The calculation uses self-consistent wave functions for each electrode; the effects of adatom valence resonances are fully taken into account. This study leads to a better understanding of important aspects of the current flow in the scanning tunneling microscope. Its emphasis is not so much on the question of resolution discussed in earlier theoretical work, but on the characteristic signatures of chemically different atoms at a surface.