No, but for the lower solar corona the electron densities are such
that collisional excitations
by electrons is the dominant mechanism creating spectral lines.
In the higher corona, photo-excitation becomes increasingly dominant,
and the spectral lines become radiatively excited.
The diagnostics to be used in this case include doppler
dimming techniques, but are not discussed here
(see, e.g. Noci et al. 1987 for details).
