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Abstract:
Picosecond time resolved luminescence was employed for monitoring the decay of electronic excited reactants on the surface of oxide semiconductors. Decay of cresyl violet monomers was determined on TiO2 and on α-Al2O3 by measuring decay curves over a wide range of very low coverages. The decay curves showed a characteristic opposite dependence on coverage on the oxide semiconductor with a low conduction band edge, i.e. TiO2, compared to the oxide semiconductor with a high conduction band edge, i.e. α-Al2O3. The dominating time constant for cresyl violet monomer decay was in the range of 280 ps on TiO2 and 560 ps on α-Al2O3. In both cases quenching was attributed to electron transfer.
At room temperature the decay of excited Cd3P2 quantum dot luminescence was faster than 1 ps when the dots were attached to TiO2 colloidal particles in solution. The ultrafast decay was ascribed to electron injection.
