Single electron tunneling and level spectroscopy of isolated C-60 molecules

The interplay between single electron tunneling effects and the discrete molecular levels of C-60 molecules is studied using scanning tunneling microscopy. Isolated C-60 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 C-60 molecular orbitals, probably due to the Jahn-Teller effect and local electric fields. (C) 1997 American Institute of Physics.