7-Diethylamino-4-methylcoumarin(coumarin 1) exhibits two amplified spontaneous emission (ASE) bands in certain solvents under pulsed laser excitation though there is only one maximum in the fluorescence spectrum. In some solvents, it exhibits only one ASE band corresponding to the fluorescence maximum, while in other solvents, the ASE band is largely red-shifted from this maximum. These laser characteristics were studied in various solvents and also in binary solvent mixtures. The study shows that the above characteristics of coumarin 1 are due to the formation of a new type of emitting species under pulsed laser excitation and that this depends upon the properties of the solvent.
