Single electron tunneling and level spectroscopy of isolated C60 molecules

The interplay between single electron tunneling effects and the discrete molecular levels of C60 molecules is studied using scanning tunneling microscopy. Isolated C60 molecules were deposited onto a gold substrate, covered by a thin insulating layer. The tunneling current–voltage characteristics of isolated molecules, both at room temperature and at 4.2 K, exhibit rich structures, resulting from the interplay between charging effects and the electronic spectrum. In particular, we observe degeneracy lifting within the C60 molecular orbitals, probably due to the Jahn–Teller effect and local electric fields.