Calculation of iron emission spectrum for a photoionized plasma (left) and a collisional plasma (right).  Though the ionization distribution is the same in both models, the spectra are quite different (and the photoionized plasma is much colder).  (Figure taken from Liedahl et al. Ap.J., 350, L37 (1990).)

Plasmas dominated by collisions and those dominated by photoionization have very different spectra