Products of photodegradation for coumarin laser dyes

The products of conventional photolysis of the coumarin laser dyes, C1, C35, C153, and C152 have been investigated. The previously reported dealkylation of C1 is documented for the fluorinated dyes, C35, and C152 in deaerated solvents. In addition, a reduction product is identified for C1, consistent with a radical mechanism for decomposition. Evidence is provided that the concentration quenching (self quenching) of singlet dye is important to the degradation mechanism. For the rigid dye, C153, a photooxidation product involving the amine functionality results from decomposition in aerated media. For several dyes, very low triplet yields have been measured.