Energy transfer and photodecomposition of anthracene laser dyes

Energy transfer from anthracene and seven anthracene derivatives to Rhodamine 6G has been studied in propan-2-ol by steady-state emission measurements. It was found that the Stern-Volmer relation is obeyed, giving rate constants of energy transfer (k(ET)) from 1.7 +/- 0.13 x 10(12) to 0.1 +/- 0.03 x 10(12) dm(3) mol(-1) s(-1). The experimental critical transfer distances, R(0), have been calculated for each dye. The values of k(ET) and R(0) indicate a Forster-type energy-transfer mechanism. The photochemical quantum yields (phi(c); lambda(ex) = 254 nm) of five anthracene laser dyes together with parent anthracene have been studied in different halomethane solvents and ethanol. The phi(4) values in CCl4 were several orders of magnitude higher than those in ethanol, and the phi(c) values decrease in the order: CCl4 > CHCl3 > CH2Cl2 greater than or equal to C2H5OH. The excited-state lifetime (tau) and the role of molecular oxygen in deactivation of the excited-singlet state of these anthracene derivatives have been studied and the second-order quenching rate constants have been determined.