  The Raman scattering spectra (RS) of two series of monolayer graphene samples
irradiated with various doses of C$^{+}$ and Xe$^{+}$ ions were measured after
annealing in high vacuum, and in forming gas (95\%Ar+5\%H$_{2}$). It was found
that these methods of annealing have dramatically different influence on the RS
lines. Annealing in vacuum below 500$^{\circ}$C leads to significant decrease
of both D-line, associated with defects, and 2D-line, associated with the
intact lattice structure, which can be explained by annealing-induced enhanced
doping. Further annealing in vacuum up to 1000$^{\circ}$C leads to significant
increase of 2D-line together with continuous decrease of D-line, which gives
evidence of partial removal of defects and recovery of the damaged lattice.
Annealing in forming gas is less effective in this sense. The blue shift of all
lines is observed after annealing. It is shown that below 500$^{\circ}$C, the
unintentional doping is the main mechanism of shift, while at higher annealing
temperatures, the lattice strain dominates due to mismatch of the thermal
expansion coefficient of graphene and the SiO$_{2}$ substrate. Inhomogeneous
distribution of stress and doping across the samples leads to the correlated
variation of the amplitude and the peak position of RS lines.
