Site-selective line-narrowed fluorescence spectra have been measured from 1.5 to 60-90 K for the S-1-->S-0 electronic transitions of phenanthrene and of perylene doped into four amorphous or nearly amorphous matrices: polyethylene, polystyrene, poly(methyl methacrylate), and ethanol. The band shapes (zero-phonon line plus phonon wing) are examined for the best-isolated strong vibronic band in the emission spectrum of each chromophore and compared with simulations using two different models that assume harmonic phonons linearly coupled to the electronic transition. One model extracts the spectral density of coupled phonons from the lowest-temperature experimental data, while the other employs an empirically determined set of harmonic phonon frequencies and coupling strengths. Good fits between simulation and experiment are obtained over the full temperature range for all chromophore-matrix combinations examined, which vary considerably in electron-phonon coupling strength. The assumption of linearly coupled harmonic phonons therefore appears to be reasonably good for these systems. Some broadening of the zero-phonon lines with increasing temperature in polystyrene and in ethanol suggests a contribution from quadratically coupled phonons as well in these matrices. (C) 2003 American Institute of Physics.