T. Urano et al., LASER-FLASH PHOTOLYSIS IN HIGH-SPEED PHOTOPOLYMER COATING LAYERS CONTAINING CARBONYLBISCOUMARIN DYES AND OPHENYL)-4,4',5,5'-TETRAPHENYL-1,1'-BI1H-IMIDAZOLE, Bulletin of the Chemical Society of Japan, 70(7), 1997, pp. 1659-1664
The sensitization mechanisms of ketocoumarin dyes with a radical-gener
ating reagent (10,10'-carbonylbis[1,1,7, ,5H,11H-[1]benzopyrano[6,7,8-
ij]quinolizin-11-one] (KCD-J), 3,3'-carbonyldis[7-(diethylamino)-2H-1-
benzopyran-2-one] (KCD-DA)) with phenyl)-4,4',5,5'-tetraphenyl-1-1'-b
i-1H-imidazole (BI) in a poly(methyl methacrylate) (PMMA) film have be
en investigated by laser-flash photolysis using a total-reflection cel
l. The triplet decay time of the dyes in a PMMA film was quenched by B
I with a k(q)s of 1.3 and 0.60 x 10(5) mol dm(-3) s(-1) for KCD-J and
KCD-DA. The fluorescence and initial absorption for KCD-DA were not qu
enched by BI in a PMMA film. The fluorescence was quenched at a quench
ing distance of 10.0 Angstrom, and the initial triplet absorption was
not quenched for KCD-J in a PMMA film. These results show that a nonst
atic sensitization from the triplet to BI is the predominant process i
n a photoinitiation system containing KCD-DA, and that both static sen
sitization from the singlet excited state to BI and nonstatic sensitiz
ation from the triplet to BI exist in a photoinitiation system contain
ing KCD-J.