Luminescence probe studies of ionomers. 3. Distribution of decay rate constants for tris(bipyridyl)ruthenium(II) in Nafion membranes

Measurements of the luminescence lifetime of Ru(bpy) sub 3(2+) (bpy = 2,2'-bipyridine) in Nafion were used to probe the heterogeneity of -SO3H(3) sites in the Nafion membrane. The decay kinetics of the probe ion are shown to depart from simple first-order behavior. Alber's model of a continuous distribution of rate constants is used to explain the decay kinetics. The results of these and related investigations indicate that the probe ions reside in sites with different local water activities.