Theory of the relation between inelastic scanning tunneling spectroscopy of adsorbates and their vibrational deexcitation

We show how the rate for controlled excitation of adsorbate vibrational mod es by scanning tunneling microscope can be quantitatively related to the li fetimes of these modes when deexciting by electron-hole pair mechanism. To this end we present a Green function formalism that accounts for the two pr ocesses in a unified way, A model calculation for an adsorbate like CO is s tudied and compared with existing experimental results. (C) 2001 Elsevier S cience B.V. All rights reserved.