Sensitization Reaction of Oxime Type Photoacid Generator

Pyrromethene dye/oxime type of photoacid generator (PAG) photoinitiating system based on the singlet electron transfer mechanism was found. The photoacid generation quantum yield (φacid) for the sensitization by the pyrromethene dye was much higher than that for the direct excitation of the PAG, giving a high sensitivity to the photopolymer. The sensitizer/PAG photoinitiating system was extended in UV light area with an anthracene derivative. The electric structure of the PAG and the radical anion were estimated by the ab initio molecular orbital (MO) calculation. The corresponding PAG radical anions give reasonable result for the enhancement of φacid.