Theory of Inelastic Electron Tunneling Spectroscopy of a Single Adsorbate with Scanning Tunneling Microscope

Abstract

Theory of inelastic electron tunneling spectroscopy (IETS) of single adsorbates on metal surfaces with scanning tun-neling microscope (STM-IETS) is presented. Adsorbate induced resonance model for studying tunneling processes via vibrational excitation of adsorbates enables us to derive general formulae for the elastic and inelastic tunneling currents. )directly reflects the vibrational density of states of adsorbates The condition under which the IETS spectrum (d2 I ／dV2 was determined. It is found that two different time scales associated with the lifetime of tunneling electrons in the adsor-bate and the residence time of electrons due to shuttling between the substrate／tip and adsorbate playimportant roles in the various features of STM-IETS spectra, including peak, dip, derivative-like or asymmetric structures.