Photoinitiation processes for photopolymer coating layers have been investigated with respect to quenching rates by a laser flash photolysis using a total reflection cell, as well as to the decomposition-quantum yield of a sensitizer dye and a radical-generating reagent by a gel permeative chromatographic analysis (GPC); the sensitizer dye, 2-
and the radical-generating reagent, 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetraphenyl-1,1'-bi-1H-imidazole (BI). From experiments using flash photolysis, strong fluorescence was observed at excitation of 355 nm laser pulse, though no transient absorption was observed. The fluorescence was statically quenched by BI with a quenching distance, R = 11 A Γ . From the experiments using GPC, the high-quantum yield of decomposition (Ξ¦) was obtained as Ξ¦ (DNT) = 3 and Ξ¦ (BI) = 9 for DNT and BI in the presence of acrylate monomers, trimethyrolpropanetri-acrylate (TMPTA), at 488 nm exposure of 3.36 mJ/cm which was required to form a photo-hardened image, however no decomposition of DNT and BI was detected in the absence of TMPTA. The results imply that the photoinitiator system undergoes efficient static-dye sensitization and efficient polymerization of the acrylate monomers accompanied with the chain decomposition of DNT and BI.