Mechanism of reaction and photoacid generation of N-oxysuccinimidoarylsulfonate PAGs: A laser flash photolytic study

The photochemical behavior of four N-oxysuccinimidoarylsulfonate photoacid generators (PAGs), 1-[[phenylsulfonyl]oxy]-(PSPD), 1-[[(4-methylphenyl)sulf onyl]oxy]-(MSPD), 1-[[(4-fluorophenyl)sulfonyl]oxy]-(FSPD), 1-[[(4-chloroph enyl)sulfonyl]oxy]-2,5-pyrrolidinedione (CSPD), has been studied by means o f nanosecond laser flash photolysis (lambda (exc) = 266 nm) and steady-stat e photolysis (lambda (exc) = 254 nm) with the aim of understanding the reac tion mechanism and, particularly, photoacid generation pathways and efficie ncy in the deep UV region. Upon photoexcitation, the formation of arylsulfo nyl radicals and their subsequent desulfonylation were detected for the fou r PAGs. In oxygen-saturated solution, the generation of the corresponding a rylperoxy radicals was also observed. Photoacid generation quantum yields u pon laser excitation were found to range from 0.04 to 0.05. Product studies following steady-state irradiations reveal that acid,generation is dominat ed by the formation of sulfonic acids.