Narrow-line fluorescence spectra of perylene as a function of excitation wavelength

Experiments on the laser excited fluorescence spectrum of perylene in n-octane and ethanol hosts at low temperatures are reported. Monochromatic excitation leads to a dramatic sharpening of the emission lines. The dependence of the spectrum on both excitation wavelength and temperature are presented and discussed qualitatively in terms of a model which applies the basic concepts of the theory of mixed crystal spectra to systems with inhomogeneous broadening.