Evaluation of Quantum Yields for Decomposition of I-Line Sensitive Photoacid Generators

Quantum yields for decomposition of a series of i-line sensitive photoacid generators were evaluated in acetonitrile solution or in polystyrene films. Sulfonate ester derivatives of N-hydroxynaphtaleneimide, fluorenone oxime, and thioxanthone oxime were investigated. Photolysis degree of photoacid generators was successfully estimated by UV or in situ FT-IR spectral changes. First-order decomposition profiles were observed for all photoacid generators on i-line irradiation. Quantum yields for decomposition (Φd) were calculated based on the rate of decomposition and molar absorption coefficient of photoacid generators. The Φd values were determined by using fluorenylideneimino p-toluenesulfonate as a standard. The Φd values of photoacid generators derived from fluorenone oxime and thioxanthone oxime were similar to those of conventional photoacid generators. The relationship between thermal stability of photoacid generators and those Φd values was also discussed.