  The inelastic electron tunneling spectrum (IETS)of highly oriented pyrolitic
graphite (HOPG) has been measured with scanning tunneling spectroscopy (STS) at
6K. The observed spectral features are in very good agreement with the
vibrational density of states (vDOS) of graphite calculated from first
principles. We discuss the enhancement of certain phonon modes by
phonon-assisted tunneling in STS based on the restrictions imposed by the
electronic structure of graphite. We also demonstrate for the first time the
local excitation of surface-plasmons in IETS which are detected at an energy of
40 meV.
