Abstract: The spectral and photochemical properties of eosin bis(diphenyl iodonium)salt and rose bengle bis(diphenyl iodonium) salt in polymer film have been studied. Their absorption spectra show a red-shift compared with those in solution and the peaks of dimers at long wavelength appear in the high XT(IPh₂)₂ concentration in the film. Upon irradiation with visible light, XT(IPh₂)₂ salts undergo electron transfer to generate leuco of dye, active phenyl radicals and iodobenzene. Owing to restriction of molecular movement in solid film, the photobleaching rates of xanthene dye anions bonded to iodonium cations(XT(IPh₂)₂) are much higher than those of two components system (XT(NEt₄₄)₂/IPh₂BF₄).

Key words: dye-sensitization, iodonium salts, electron trasfer, ion pair