Spectroscopic and lasing characteristics of 7-N,N-diallylamino(-3-aryl)-coumarins and 2-pyrazolines—a new class of potential laser dyes

The near UV absorption spectra and fluorescence spectra of new coumarin dyes and pyrazolines synthesized in our laboratories are investigated in solution. The effects of solvent and pH factor on the absorption and fluorescence maxima are also studied. The fluorescence lifetimes of coumarins are determined in different solvents. The regression relations for the absorption maxima, fluorescence maxima and fluorescence lifetimes as a function of polarity, refractive index and dielectric constant of the solvent are derived. The lasing maximum peak and range are determined for four of the new coumarins using the Nitrogen Pulsed Dye Laser at L and PT Division, BARC, Bombay. All the dyes investigated are of purity > 99% as determined by high performance liquid chromatography (HPLC). The NMR, mass and IR spectra are recorded for examining the structures. All dyes tested for lasing characteristics are found to be good laser dyes in the blue—green region.