Possible influence of phonons on stimulated emission from doped molecular crystals

An investigation was made of the spectra and intensities of stimulated emission from naphthalene single crystals doped with ββ'-dinaphthylethylene and excited with giant ultraviolet pulses of various energies in the absorption band of the impurity. An increase in the impurity concentration gave rise to the appearance, in the stimulated emission spectrum, not only of a zero-phonon line but also of a band corresponding to the phonon wing frequencies. The intensity of the zero-phonon line reached saturation when the pump energy was increased but the intensity of the phonon wing grew proportionally to the pump energy. A study was made of the influence of temperature on the behavior of the stimulated emission lines. The results obtained were explained on the hypothesis of the phonon participation in the stimulated emission process.