Abstract

Non-rigidised amino coumarin dye molecules such as DAMC have been postulated to have intramolecular charge transfer (ICT) and twisted intra molecular charge transfer (TICT) states [1].These states are separated by an energy barrier whose height decreases with increasing polarity of the solvent. Though other structurally similar molecules having TICT states, such as DMABN, show fluorescence from both ICT and TICT states [2], DAMC does not exhibit dual fluorescence even in polar solvents, indicating rapid non radiative decay of the TICT state to the ground state through internal conversion (IC). However lasing occurs simultaneously at two wavelengths from these dyes under intense pumping by nano second pulses from a nitrogen laser (fig. 1).

© 1996 Optical Society of America