The authors apply methods of quantum chemistry to obtain information on the equilibrium geometrical structure, IR and UV spectra of the photoacid generator (PAG) di(phenylsulphonyl) diazomethane (DPSD) and products of its photoinduced decomposition, and UV spectra of polyhydroxystyrene (PHOST) and poly(4-t-butoxycarbonyloxystyrene) (PTBOCST), and to characterize a viable alternative path for photoinduced decomposition of DPSD in PHOST-like resists. In contrast with previously published sulphone-based chemistry, the newly suggested path for acid generation results in formation of up to two acid molecules per single PAG molecule. The theoretical results are quantitatively compared with available experimental data. (c) 2007 American Vacuum Society.