  Graphene grown by chemical vapor deposition and supported on SiO2 and
sapphire substrates was studied following controlled introduction of defects
induced by 35 keV carbon ion irradiation. Changes in Raman spectra following
fluences ranging from 10^12 cm^-2 to 10^15 cm^-2 indicate that the structure of
graphene evolves from a highly ordered layer, to a patchwork of disordered
domains, to an essentially amorphous film. These structural changes result in a
dramatic decrease in the Hall mobility by orders of magnitude while,
remarkably, the Hall concentration remains almost unchanged, suggesting that
the Fermi level is pinned at a hole concentration near 1x10^13 cm^-2. A model
for scattering by resonant scatterers is in good agreement with mobility
measurements up to an ion fluence of 1x10^14 cm^-2.
