Femtosecond study of the intensity dependence of electron-hole dynamics in TiO 2 nanoclusters

• Published in: Chemical physics letters Vol. 232; no. 3; pp. 207 - 214
• Main Authors: Philip Colombo, D., Roussel, Kirsten A., Saeh, Jamal, Skinner, David E., Cavaleri, Joseph J., Bowman, Robert M.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 1995
• ISSN: 0009-2614; 1873-4448
• DOI: 10.1016/0009-2614(94)01343-T

The dynamics of charge carrier trapping and recombination as a function of pump fluence of 20 Å diameter TiO 2 particles in aqueous solutions is measured. Trapping of photogenerated conduction band electrons occurs in less than 500 fs. The subsequent fluence-dependent decay of trapped electrons has both a fast and a slow component. The early time recombination results are interpreted by second-order kinetics. A global fit to the data predicts a bulk second-order recombination rate constant of (1.8 ± 0.7) × 10 −10 cm 3 s −1 for trapped electrons with holes. The signal at long times is attributed to electrons ejected from the nanocluster and/or deeply trapped electrons produced via third-order kinetics, consistent with an Auger process.