Excited-state dynamics of size-dependent colloidal TiO{sub 2}-Au nanocomposites
The ultrafast excited-state dynamics of size-dependent TiO{sub 2}-Au nanocomposites synthesized by reducing gold nanoclusters to the surface of colloidal TiO{sub 2} nanoparticles are studied using pump-probe transient absorption spectroscopy with 400 nm excitation pulses. The results show that the relaxation processes of the plasmon depletion band, which are described by electron-phonon and phonon-phonon scattering lifetimes, are independent of the gold nanocluster shell size surrounding the TiO{sub 2} nanoparticle core. The dynamics corresponding to interfacial electron transfer between the gold nanoclusters and the TiO{sub 2} bandgap are observed to spectrally overlap with the gold interband transition signal, and the electron transfer lifetimes are shown to significantly decrease as the nanocluster shell size increases. Additionally, size-dependent periodic oscillations are observed and are attributed to acoustic phonons of a porous shell composed of aggregated gold nanoclusters around the TiO{sub 2} core, with frequencies that decrease and damping times that remain constant as the nanocluster shell size increases. These results are important for the development of improved catalytic nanomaterial applications.
- OSTI ID:
- 22657873
- Journal Information:
- Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 12 Vol. 144; ISSN JCPSA6; ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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