Tunneling spectroscopy of fullerene/Ge multilayer systems

We report on an IETS (inelastic electron tunneling spectroscopy) technique which has successfully resolved 40 of the 46 C60 intramolecular vibrational modes and ∼50 of the 122 modes of C70. By layering thin, thermally evaporated films of germanium and fullerene molecules, composite multilayer tunnel barriers are formed which appear to produce enhanced IET results. IETS is in general not selection-rule restricted and has the potential to present all non-degenerate vibrational modes.