Measurements of Energy Dispersion at Liquid-Solid Interfaces: FluorescenceQuenching of Pyrene Bound to Fumed Silica

摘要

The observation of a stretched exponential response in chemical kinetics at solid-liquid interfaces is an indicator of solid surface disorder. In this contribution, we review earlier relaxation kinetics studies of solid surface disorder and the statistical criteria analyzing kinetic data which are not single exponential. We draw on these concepts to interpret the fluorescence decay kinetics of pyrene covalently attached to the surface of fumed silica particles which are suspended in methanol. These results, along with the diffusional length of the iodine quencher, the photophysics of the probe, and the chemistry of the interface, indicate that the kinetic inhomogeneity is dominated by dispersion of surface energies, rather than by diffusional excursions of the quencher on a fractally aggregated surface. (jes)