Field-emission electron spectroscopy of single-atom tips

Abstract

We show here that the experimental field-emission electron spectra from W nanoprotrusion tips ending in a single atom consist solely of well-separated peaks. Each spectrum shifts linearly with the applied field-emission voltage. The peaks in the spectra strongly suggest that the tunneling occurs only through a localized band structure at the topmost atom. A charge confinement and a field penetration over the top atom is introduced to explain the linear shifts.