| Summary: | The effect of titania-silica binaries on the processes of PET and the decay kinetics of the
Anthracene (An) fluorescence and An radical cation in presence of the co-adsorbed electron donor N,Ndimethylaniline
(DMA) has been studied. The fluorescence of excited An adsorbed on pure silica is quenched
by the addition of DMA, while co-adsorption of DMA on Ti/Si binaries resulted in increase of fluorescence
intensity of adsorbed An. We suggest that competitive adsorption between DMA and An results in DMA
occupying more active “titania” sites causing the shift of An molecules to weaker adsorption sites located
on the silica support. An and DMA molecules being adsorbed simultaneously on the surface, effectively produce
reduced titanium ions due to an electron transfer process. These data appear to lend weight to the
suggestion of a pre-exciplex An-DMA state on the surface and effective PET from the excited molecular pair
to the acceptor sites on the surface. These sites may be titania aggregates, or titania ions when there is a low
content of Ti in the binaries.
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