  We report low temperature high magnetic field scanning tunneling microscopy
and spectroscopy of graphene flakes on graphite that exhibit the structural and
electronic properties of graphene decoupled from the substrate. Pronounced
peaks in the tunneling spectra develop with field revealing a Landau level
sequence that provides a direct way to identify graphene and to determine the
degree of its coupling to the substrate. The Fermi velocity and quasiparticle
lifetime, obtained from the positions and width of the peaks, provide access to
the electron-phonon and electron-electron interactions.
