The behavior of excited [image omitted] with the electron-acceptor quenchers methyl viologen and C60F36 in ethanol containing Nafion ionomer and in the water nanochannels of Nafion membrane was investigated by measurement of luminescence quenching. In Nafion ionomer solution, [image omitted] and methyl viologen are adsorbed onto Nafion aggregates, whereas C60F36 is held in Nafion aggregates. In the nanochannels of Nafion membrane, [image omitted] and methyl viologen were found to diffuse, even though the diffusion constant was ca. 1/20 of that in bulk ethanol solvent.