Laser flash photolysis in high speed photopolymer coating layers III: Sensitization mechanisms of aminochalcone-type dyes with a radical-generating reagent

In order to get insight into the effect of the different fixations of the c onjugated systems of the aminochalcone-dyes on both the photophysical behav ior and the quenching scheme of photoinitiation systems in a him, photophys ical behavior of 2-benzoyl-6-(dimethylamino)benzo[b]furan (A) on 355 nm exc itation with or without a radical-generating reagent, 2,4,6-tris(trichlorom ethyl)-1,3,5-triazine (TRI), in poly(methyl methacrylate) (PMMA) film has b een investigated by la ser flash photolysis using a total reflection cell. Dye A showed characteristic dual fluorescences of which the lifetimes, tau (s)s, of shorter- and longer-wavelength components were evaluated to be 3.2 and 5.4 ns, respectively. The fluorescences were quenched by TRI with diff erent static quenching distances, (R-s)(s)s, of 1.3 and 1.5 nm for A(short) and A(long), respectively. The static quenching distance of the initial tr iplet absorption of A, (R-s)(T), was evaluated to be 1.5 nm. In addition, d econvolution analysis of the lifetimes of fluorescent dyes has been carried out to clarify the property of nonstatic quenching of the dyes: A, 10-benz oyl-2,3,6,7-tetrahydro-1H,5H-furo[3,2-g]pyrido[3,2,1-ij]quinoline (B), 4'-( dimethylamino)chalcone (C), and (E)-3-(9-julolidinyl)-1-phenyl-2-propen-1-o ne (D), with TRI in the film.