The halogenation of resist materials is a well-known strategy for the improvement in resist performance particularly in electron beam and x-ray resists. However, for chemically amplified resists, the halogenation of polymers requires particular caution because halogenated polymers may interfere with acid generation. In this work, acid generation in poly[4-hydroxystyrene-co-4- (1,1,1,3,3,3 -hexafluoro-2-hydroxypropyl) -styrene] films was investigated using steady-state spectroscopy and pulse radiolysis. Acid yield decreased with an increase in the ratio of hexafluoroalcohol units. It was found that the reactivity of polymers with low-energy electrons (similar to thermal energy) correlates to the decrease in acid yield. (c) 2006 American Vacuum Society.