Lasing properties of 7-hydroxy-4-trifluoromethylcoumarin excited by an excimer laser

A study was made of the lasing properties of 7-OH-4-trifluoromethylcoumarin (F4MU) excited by an XeCl* excimer laser using various solvents (acetic acid, ethanol, water-ethanol mixtures, acidified water-ethanol mixtures, concentrated sulfuric acid). Theoretical calculations were made of the systems of electronic levels of F4MU and its protolytic forms. The absorption from the lower excited singlet level to the upper singlet levels and from the lower triplet level to the upper triplet levels was also calculated. It was found that in the case of F4MU the tuning range is wider than that of unfluorinated analogs (umbelliferone and 4-methylumbelliferone), and the lasing efficiency of the neutral and anionic forms is improved considerably. In addition, by using an excimer laser, lasing can be achieved in all protolytic forms of F4MU, so that the tuning range is increased compared with flashlamp excitation.