Initial step of anthracene-sensitized photoacid generation from diphenyliodonium hexafluorophosphate in an epoxy matrix studied by steady-state and laser-flash photolyses

The anthracene-sensitized photodecomposition of diphenyliodonium hexafluoro phosphate was studied in an epoxy matrix. From steady-state photolysis, the generation of protons, which are considered to be the actual initiators of the polymerization of epoxides, was confirmed. In addition, 9-phenylanthra cene was detected as a main product from anthracene. From time-resolved las er-flash photolysis, a broad absorption band with a peak at about 500 nm wa s observed that was thought to be due to the precursor of 9-phenylanthracen e. On the basis of these results, we propose electron transfer from anthrac ene in the excited singlet state to the diphenyliodonium. cation as the ini tial step of photoacid generation. This process is followed by fast chemica l reactions, which generate 9-phenylanthracene and protons, and back electr on transfer from the diphenyliodine radical to the anthracene cation radica l. (C) 2001 John Wiley & Sons, Inc.*.