Photochemistry and picosecond absorption spectra of aqueous suspensions of a polycrystalline titanium dioxide optically transparent in the visible spectrum

摘要: Abstract Optically transparent suspensions of (Degussa P25) titanium dioxide which mimic well the photochemical and photophysical properties bulk material were prepared by sequential centrifugation. Quantum yields photocatalyzed oxidation I − propanal measured under monochromatic 313 nm irradiation found to be very similar those estimated for concentrated P25 slurries but higher than in colloidal TiO 2 solutions. A unit limiting quantum yield photooxidation suggests efficient utilization photogenerated holes. Time-resolved absorption spectra 50 ps-10 ns time interval following excitation a 30 ps, 355 laser pulse definitely different from picosecond observed earlier colloids. It is proposed that transient signal may arise hole undergoes thermalization surface-trapping with lifetime approximately 1 ns.