Fluorescence and lasing of nonequilibrium protolytic forms of polymethine dye molecules

A study was made of photoprotolytic reactions which take place in the excited state of a new series of polymethine dye molecules used as active media of lasers. The fluorescence quantum efficiencies of protonated and deprotonated forms, quantum efficiency of the proton attachment process, and deprotonation and protonation constants were determined. A system of energy levels and channels of radiative and nonradiative transitions was proposed for the series of dyes under study. Laser action was obtained in the deprotonated forms produced in the excited state from the protonated forms. Methods of enhancing the lasing efficiency of nonequilibrium protolytic forms of polymethine dye molecules and fields of application of this type of active medium are discussed.