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 coumari n dyes and pyrazolines synthesized in our laboratories are investigate d in solution. The effects of solvent and pH factor on the absorption and fluorescence maxima are also studied. The fluorescence lifetimes o f coumarins are determined in different solvents. The regression relat ions for the absorption maxima, fluorescence maxima and fluorescence l ifetimes as a function of polarity, refractive index and dielectric co nstant of the solvent are derived. The lasing maximum peak and range a re determined for four of the new coumarins using the Nitrogen Pulsed Dye Laser at L and PT Division, BARC, Bombay. All the dyes investigate d are of purity > 99% as determined by high performance liquid chromat ography (HPLC). The NMR, mass and IR spectra are recorded for examinin g the structures. All dyes tested for lasing characteristics are found to be good laser dyes in the blue-green region.