Excitation of Jahn−Teller Active Modes during Electron Transport through Single C60 Molecules on Metal Surfaces

Abstract

Using scanning tunneling spectroscopy, we resolve all Jahn−Teller active Hg modes of a single C60 molecule when adsorbed on a Pb(111) surface. Selection rules for vibrational excitation in inelastic tunneling spectra are thus given by the electron−phonon coupling in the molecular orbital close to the Fermi level. The observation of modes depends, however, crucially on the orbital alignment. In particular, inelastic spectra in a resonant tunneling regime, as realized by adsorption of C60 on Cu(111), show no vibrational fingerprint.