Isochromat spectroscopy of photons emitted from metal surfaces in an STM

Abstract

The pronounced variation of the intensity of photons emitted from the tunneling gap of an STM with respect to the applied bias voltage Vt is studied experimentally using simultaneous measurements of tunneling characteristics and photon emission. We show that the structure in isochromat photon spectra are determined by the following: bias‐dependent changes in tunneling characteristics, density of initial and final states, and modifications of tip‐induced plasmon modes. It is demonstrated that isochromat spectra provide a conclusive test for the inelastic tunneling mechanism. Coupling between tunneling electrons and tip‐induced plasmon modes which gives rise to the intense photon emission observed is discussed within this model. Copyright © 1993 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim